RESUMO
BACKGROUND: Dairy cattle breeds are populations of limited effective size, subject to recurrent outbreaks of recessive defects that are commonly studied using positional cloning. However, this strategy, based on the observation of animals with characteristic features, may overlook a number of conditions, such as immune or metabolic genetic disorders, which may be confused with pathologies of environmental etiology. RESULTS: We present a data mining framework specifically designed to detect recessive defects in livestock that have been previously missed due to a lack of specific signs, incomplete penetrance, or incomplete linkage disequilibrium. This approach leverages the massive data generated by genomic selection. Its basic principle is to compare the observed and expected numbers of homozygotes for sliding haplotypes in animals with different life histories. Within three cattle breeds, we report 33 new loci responsible for increased risk of juvenile mortality and present a series of validations based on large-scale genotyping, clinical examination, and functional studies for candidate variants affecting the NOA1, RFC5, and ITGB7 genes. In particular, we describe disorders associated with NOA1 and RFC5 mutations for the first time in vertebrates. CONCLUSIONS: The discovery of these many new defects will help to characterize the genetic basis of inbreeding depression, while their management will improve animal welfare and reduce losses to the industry.
Assuntos
Genes Recessivos , Animais , Bovinos , Mineração de Dados , Doenças dos Bovinos/genética , HaplótiposRESUMO
BACKGROUND: Alzheimer's disease (AD) heritability is estimated to be around 70-80%. Yet, much of it remains to be explained. Studying transmission patterns may help in understanding other factors contributing to the development of AD. OBJECTIVE: In this study, we aimed to search for evidence of autosomal recessive or X- and Y-linked inheritance of risk factors in a large cohort of Portuguese AD patients. METHODS: We collected family history from patients with AD and cognitively healthy controls over 75 years of age. We compared the proportions of maternal and paternal history in male and female patients and controls (to search for evidence of X-linked and Y-linked inherited risk factors). We compared the risk of developing AD depending on parents' birthplace (same vs. different), as a proxy of remote consanguinity. We performed linear regressions to study the association of these variables with different endophenotypes. RESULTS: We included 3090 participants, 2183 cognitively healthy controls and 907 patients with AD. Men whose mother had dementia have increased odds of developing AD comparing to women whose mother had dementia. In female patients with a CSF biomarker-supported diagnosis of AD, paternal history of dementia is associated with increased CSF phosphorylated Tau levels. People whose parents are from the same town have higher risk of dementia. In multivariate analysis, this proxy is associated with a lower age of onset and higher CSF phosphorylated tau. CONCLUSIONS: Our study gives evidence supporting an increased risk of developing AD associated with an X-linked inheritance pattern and remote consanguinity.
Assuntos
Doença de Alzheimer , Humanos , Masculino , Feminino , Doença de Alzheimer/genética , Doença de Alzheimer/epidemiologia , Portugal/epidemiologia , Idoso , Fatores de Risco , Idoso de 80 Anos ou mais , Estudos de Coortes , Predisposição Genética para Doença , Genes Ligados ao Cromossomo X , Genes Recessivos , Proteínas tau/líquido cefalorraquidiano , Proteínas tau/genética , Cromossomos Humanos X/genéticaRESUMO
Distal hereditary motor neuropathies (dHMN) are a group of heterogeneous diseases and previous studies have reported that the compound heterozygous recessive MME variants cause dHMN. Our study found a novel homozygous MME variant and a reported compound heterozygous MME variant in two Chinese families, respectively. Next-generation sequencing and nerve conduction studies were performed for two probands. The probands in two families presented with the muscle weakness and wasting of both lower limbs and carried a c.2122 A > T (p.K708*) and c.1342 C > T&c.2071_2072delinsTT (p.R448*&p.A691L) variant, respectively. Prominently axonal impairment of motor nerves and slight involvement of sensory nerves were observed in nerve conduction study. Our study reported a "novel" nonsense mutation and a missense variant of autosomal recessive late-onset dHMN and reviewed reported MME variants associated with dHMN phenotype.
Assuntos
Neuropatia Hereditária Motora e Sensorial , Neprilisina , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Idade de Início , Alelos , China , Códon sem Sentido , População do Leste Asiático/genética , Genes Recessivos , Neuropatia Hereditária Motora e Sensorial/genética , Linhagem , Neprilisina/genéticaRESUMO
Autosomal-recessive cutis laxa type 2 (ARCL2) is a rare genetic disorder caused by pyrroline-5-carboxylate reductase 1 (PYCR1) mutations and characterized by loose and sagging skin, typical facial features, intrauterine growth retardation, and developmental delay. To study the effect of PYCR1 mutations on protein function and clinical features, we identified a homozygous missense mutation c.559G > A (p.Ala187Thr) in PYCR1 in a Chinese child with typical clinical features, especially severe developmental delays. The three-dimensional (3D) model showed the modification of the hydrogen bonds produce a misfolding in the mutant PYCR1 protein. Mutagenesis and enzyme assay study revealed decreased activity of the mutant protein in vitro, indicating that this mutation impairs PYCR1 function. Our findings confirmed abnormal enzymatic activity and neurodevelopmental trajectory of this PYCR1 mutation.
Assuntos
Cútis Laxa , Mutação de Sentido Incorreto , Pirrolina Carboxilato Redutases , delta-1-Pirrolina-5-Carboxilato Redutase , Humanos , Cútis Laxa/genética , Cútis Laxa/patologia , Pirrolina Carboxilato Redutases/genética , Pirrolina Carboxilato Redutases/metabolismo , Masculino , Feminino , Pré-Escolar , Modelos Moleculares , Deficiências do Desenvolvimento/genética , Deficiências do Desenvolvimento/patologia , Homozigoto , Genes Recessivos , MutaçãoRESUMO
Autosomal recessive non-syndromic hearing loss (ARNSHL) can cause severe or very severe pre-speech hearing loss. Transmembrane channel-like 1 (TMC1) gene is the sixth deafness gene discovered, but the precise extent of its protein structure and function is unknown. First, history collection, audiology examination and imaging examination were performed on the proband and his family members. Peripheral blood of proband and family members was collected, genomic DNA was extracted, exon high-throughput sequencing technology was used to detect the deafness gene mutation of the proband, and Sanger sequencing was performed to verify the TMC1 gene of the proband's parents. The proband was born with hearing impairment, normal tympanic function, inability to induce acoustic reflex in both ears (acoustic reflex threshold is 100 dBHL), and severe sensorineural deafness. One of his sisters has severe sensorineural hearing loss, and neither his parents nor his other sister is hearing impaired. High-throughput sequencing of the proband identified mutations at c.741+3_741+6delAAGT (splicing) and c.884C>T (p.A295V) of the TMC1 gene, two of which were heterozygous mutations. Sanger sequencing confirmed that the c.884C > T mutation was inherited from the mother, while the c.741+3_741+6delAAGT mutation was derived from the father. Prediction of amino acid function suggested that both mutations were pathogenic mutations. In conclusion, we found a new pathogenic complex heterozygous mutation of the TMC1 gene, which enriched the mutation spectrum of the TMC1 gene and provided a basis for genetic counseling and prenatal diagnosis of ARNSHL.
Assuntos
Heterozigoto , Proteínas de Membrana , Linhagem , Humanos , Masculino , Proteínas de Membrana/genética , Feminino , Mutação/genética , Surdez/genética , Sequenciamento de Nucleotídeos em Larga Escala , Genes Recessivos/genética , Perda Auditiva Neurossensorial/genética , Adulto , Sequência de BasesRESUMO
Noonan syndrome patients harboring causative variants in LZTR1 are particularly at risk to develop severe and early-onset hypertrophic cardiomyopathy. In this study, we investigate the mechanistic consequences of a homozygous variant LZTR1L580P by using patient-specific and CRISPR-Cas9-corrected induced pluripotent stem cell (iPSC) cardiomyocytes. Molecular, cellular, and functional phenotyping in combination with in silico prediction identify an LZTR1L580P-specific disease mechanism provoking cardiac hypertrophy. The variant is predicted to alter the binding affinity of the dimerization domains facilitating the formation of linear LZTR1 polymers. LZTR1 complex dysfunction results in the accumulation of RAS GTPases, thereby provoking global pathological changes of the proteomic landscape ultimately leading to cellular hypertrophy. Furthermore, our data show that cardiomyocyte-specific MRAS degradation is mediated by LZTR1 via non-proteasomal pathways, whereas RIT1 degradation is mediated by both LZTR1-dependent and LZTR1-independent pathways. Uni- or biallelic genetic correction of the LZTR1L580P missense variant rescues the molecular and cellular disease phenotype, providing proof of concept for CRISPR-based therapies.
Assuntos
Células-Tronco Pluripotentes Induzidas , Miócitos Cardíacos , Síndrome de Noonan , Proteínas ras , Humanos , Síndrome de Noonan/genética , Síndrome de Noonan/patologia , Síndrome de Noonan/metabolismo , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/patologia , Proteínas ras/metabolismo , Proteínas ras/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Mutação/genética , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/patologia , Cardiomiopatia Hipertrófica/metabolismo , Polimerização , Sistemas CRISPR-Cas/genética , Proteólise , Mutação de Sentido Incorreto , Multimerização Proteica , Genes Recessivos , FenótipoRESUMO
Deafness in vertebrates is associated with variants of hundreds of genes. Yet, many mutant genes causing rare forms of deafness remain to be discovered. A consanguineous Pakistani family segregating nonsyndromic deafness in two sibships were studied using microarrays and exome sequencing. A 1.2 Mb locus (DFNB128) on chromosome 5q11.2 encompassing six genes was identified. In one of the two sibships of this family, a novel homozygous recessive variant NM_005921.2:c.4460G>A p.(Arg1487His) in the kinase domain of MAP3K1 co-segregated with nonsyndromic deafness. There are two previously reported Map3k1-kinase-deficient mouse models that are associated with recessively inherited syndromic deafness. MAP3K1 phosphorylates serine and threonine and functions in a signaling pathway where pathogenic variants of HGF, MET, and GAB1 were previously reported to be associated with human deafness DFNB39, DFNB97, and DFNB26, respectively. Our single-cell transcriptome data of mouse cochlea mRNA show expression of Map3k1 and its signaling partners in several inner ear cell types suggesting a requirement of wild-type MAP3K1 for normal hearing. In contrast to dominant variants of MAP3K1 associated with Disorders of Sex Development 46,XY sex-reversal, our computational modeling of the recessive substitution p.(Arg1487His) predicts a subtle structural alteration in MAP3K1, consistent with the limited phenotype of nonsyndromic deafness.
Assuntos
Surdez , Genes Recessivos , MAP Quinase Quinase Quinase 1 , Linhagem , Animais , Camundongos , Humanos , Feminino , Masculino , Surdez/genética , MAP Quinase Quinase Quinase 1/genética , MAP Quinase Quinase Quinase 1/metabolismo , Modelos Animais de Doenças , Perda Auditiva/genética , Sequenciamento do Exoma , ConsanguinidadeRESUMO
Progressive retinal atrophies (PRAs) are a genetically heterogeneous group of inherited eye diseases that affect over 100 breeds of dog. The initial clinical sign is visual impairment in scotopic conditions, as a consequence of rod photoreceptor cell degeneration. Photopic vision degeneration then follows, due to progression of the disease to the cone photoreceptors, and ultimately results in complete blindness. Two full-sibling English Shepherds were diagnosed with PRA at approximately 5 years old and tested clear of all published PRA genetic variants. This study sought to identify the novel PRA-associated variant segregating in the breed. We utilised a combined approach of whole genome sequencing of the probands and homozygosity mapping of four cases and 22 controls and identified a short interspersed nuclear element within an alternatively spliced exon in FAM161A. The XP_005626197.1 c.17929_ins210 variant was homozygous in six PRA cases and heterozygous or absent in control dogs, consistent with a recessive mode of inheritance. The insertion is predicted to extend exon 4 by 39 aberrant amino acids followed by an early termination stop codon. PRA is intractable to treatment, so the development of a genetic screening test, based on the associated variant, is significant, because it provides dog breeders/owners with a means of reducing the frequency of the disease variant within this breed as well as minimising the risk of breeding puppies that will develop this blinding disease.
Assuntos
Doenças do Cão , Éxons , Animais , Cães , Éxons/genética , Doenças do Cão/genética , Doenças do Cão/patologia , Elementos Nucleotídeos Curtos e Dispersos/genética , Degeneração Retiniana/genética , Degeneração Retiniana/veterinária , Degeneração Retiniana/patologia , Feminino , Masculino , Linhagem , Genes Recessivos , Mutagênese Insercional , Proteínas do Olho/genética , Sequenciamento Completo do GenomaRESUMO
Arthrogryposis is a clinical feature defined by congenital joint contractures in two or more different body areas which occurs in between 1/3000 and 1/5000 live births. Variants in multiple genes have been associated with distal arthrogryposis syndromes. Heterozygous variants in MYH3 have been identified to cause the dominantly-inherited distal arthrogryposis conditions, Freeman-Sheldon syndrome, Sheldon-Hall syndrome, and multiple pterygium syndrome. In contrast, MYH3 variants underlie both dominantly and recessively inherited Contractures, Pterygia, and Spondylocarpotarsal Fusion syndromes (CPSFS) which are characterized by extensive bony abnormalities in addition to congenital contractures. Here we report two affected sibs with distal arthrogryposis born to unaffected, distantly related parents. Sequencing revealed that both sibs were homozygous for two ultra-rare MYH3 variants, c.3445G>A (p.Glu1149Lys) and c.4760T>C (p.Leu1587Pro). Sequencing and deletion/duplication analysis of 169 other arthrogryposis genes yielded no other compelling candidate variants. This is the first report of biallelic variants in MYH3 being implicated in a distal arthrogryposis phenotype without the additional features of CPSFS. Thus, akin to CPSFS, both dominant and recessively inherited distal arthrogryposis can be caused by variants in MYH3.
Assuntos
Alelos , Artrogripose , Genes Recessivos , Humanos , Artrogripose/genética , Artrogripose/patologia , Masculino , Feminino , Linhagem , Proteínas Motores Moleculares/genética , Mutação/genética , Fenótipo , Predisposição Genética para Doença , Proteínas do CitoesqueletoRESUMO
BACKGROUND: NOTCH3 variants are known to be linked to cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). However, some null NOTCH3 variants with homozygous inheritance cause neurological symptoms distinct from CADASIL. The aim of this study was to expand the clinical spectrum of this distinct condition and provide further evidence of its autosomal recessive inheritance. METHODS AND RESULTS: Whole exome sequencing (WES) was performed on a proband who exhibited livedo racemosa, ataxia, cognitive decline, seizures, and MRI white matter abnormalities without anterior temporal pole lesions. Segregation analysis was conducted with Sanger sequencing. WES of the proband identified a novel homozygous NOTCH3 null variant (c.2984delC). The consanguineous parents were confirmed as heterozygous variant carriers. In addition, three heterozygous NOTCH3 null variants were reported as incidental findings in three unrelated cases analyzed in our center. CONCLUSION: The findings of this study suggest an autosomal recessive inheritance pattern in this early-onset leukoencephalopathy, in contrast to CADASIL's dominant gain-of-function mechanism; which is a clear example of genotype-phenotype correlation. Comprehensive genetic analysis provides valuable insights into disease mechanisms and facilitates diagnosis and family planning for NOTCH3-associated neurological disorders.
Assuntos
Sequenciamento do Exoma , Genes Recessivos , Linhagem , Fenótipo , Receptor Notch3 , Humanos , Receptor Notch3/genética , Masculino , Feminino , Sequenciamento do Exoma/métodos , Genes Recessivos/genética , Adulto , Estudos de Associação Genética , CADASIL/genética , Imageamento por Ressonância Magnética/métodos , Alelos , Homozigoto , Consanguinidade , Mutação com Perda de Função/genética , Mutação/genética , HeterozigotoRESUMO
The evolution of suppressed recombination between sex chromosomes is widely hypothesized to be driven by sexually antagonistic selection (SA), where tighter linkage between the sex-determining gene(s) and nearby SA loci is favored when it couples male-beneficial alleles to the proto-Y chromosome, and female-beneficial alleles to the proto-X. Although difficult to test empirically, the SA selection hypothesis overshadows several alternatives, including an incomplete but often-repeated "sheltering" hypothesis which suggests that expansion of the sex-linked region (SLR) reduces the homozygous expression of deleterious mutations at selected loci. Here, we use population genetic models to evaluate the consequences of partially recessive deleterious mutational variation for the evolution of otherwise neutral chromosomal inversions expanding the SLR on proto-Y chromosomes. Both autosomal and SLR-expanding inversions face a race against time: lightly-loaded inversions are initially beneficial, but eventually become deleterious as they accumulate new mutations, after which their chances of fixing become negligible. In contrast, initially unloaded inversions eventually become neutral as their deleterious load reaches the same equilibrium as non-inverted haplotypes. Despite the differences in inheritance and indirect selection, SLR-expanding inversions exhibit similar evolutionary dynamics to autosomal inversions over many biologically plausible parameter conditions. Differences emerge when the population average mutation load is quite high; in this case large autosomal inversions that are lucky enough to be mutation-free can rise to intermediate to high frequencies where selection in homozygotes becomes important (Y-linked inversions never appear as homozygous karyotypes); conditions requiring either high mutation rates, highly recessive deleterious mutations, weak selection, or a combination thereof.
Assuntos
Inversão Cromossômica , Evolução Molecular , Recombinação Genética , Masculino , Feminino , Seleção Genética , Modelos Genéticos , Animais , Variação Genética , Cromossomos Sexuais/genética , Genes RecessivosRESUMO
Mutations in the gene SCAPER (S phase Cyclin A-Associated Protein residing in the Endoplasmic Reticulum) have recently been associated with retinitis pigmentosa (RP) and intellectual disability (ID). In 2011, a possible involvement of SCAPER in human diseases was discovered for the first time due to the identification of a homozygous mutation causing ID in an Iranian family. Later, five studies were published in 2019 that described patients with autosomal recessive syndromic retinitis pigmentosa (arRP) accompanied by ID and attention-deficit/hyperactivity disorder (ADHD). This present study describes three patients from an Arab consanguineous family in Israel with similar clinical features of the SCAPER syndrome. In addition, new manifestations of ocular symptoms, nystagmus, glaucoma, and elevator palsy, were observed. Genetic testing of the patients and both parents via whole-exome sequencing revealed the homozygous mutation c.2023-2A>G in SCAPER. Phenotypic and genotypic descriptions for all available cases described in the literature including our current three cases (37 cases) were carried out, in addition to a bioinformatics analysis for all the genetic variants that was undertaken. Our study confirms and extends the clinical manifestations of SCAPER-related disorders.
Assuntos
Biologia Computacional , Deficiência Intelectual , Mutação , Linhagem , Fenótipo , Retinose Pigmentar , Adolescente , Adulto , Feminino , Humanos , Proteínas de Transporte/genética , Biologia Computacional/métodos , Consanguinidade , Sequenciamento do Exoma , Genes Recessivos , Homozigoto , Deficiência Intelectual/genética , Deficiência Intelectual/patologia , Peptídeos e Proteínas de Sinalização Intercelular , Retinose Pigmentar/genética , Retinose Pigmentar/patologiaRESUMO
BACKGROUND: Primary ovarian insufficiency (POI) affects around 2-4% of women before the age of 40. Genetic factors play an important role in POI. The GDF9 gene has been identified as a significant genetic contributor of POI. However, the pathogenicity and penetrance of GDF9 variants remain uncertain. METHODS: A next-generation sequencing approach was employed to investigate the entire coding region of the GDF9 gene in a cohort of 1281 patients with POI or diminished ovarian reserve (DOR). The frequency of each identified GDF9 variant was then compared with that of the general population, taking into account the ethnicity of each individual. RESULTS: By screening the entire coding region of the GDF9 gene, we identified 19 different variants, including 1 pathogenic frameshift variant. In total, 36 patients with POI/DOR (2.8%) carried at least one GDF9 variant. With regard to missense variants, no significant overrepresentation of the most common variants was observed in our POI/DOR cohort in comparison to the general or specific ethnic subgroups. Only one homozygous subject had a frameshift loss of function variant. CONCLUSION: This epidemiological study suggests that the vast majority of heterozygous missense variants could be considered as variants of uncertain significance and the homozygous loss-of-function variant could be considered as a pathogenic variant. The identification of a novel case of a homozygous POI patient with a heterozygous mother carrying the same variant with normal ovarian function strongly suggests that GDF9 syndrome is an autosomal recessive disorder.
Assuntos
Fator 9 de Diferenciação de Crescimento , Insuficiência Ovariana Primária , Humanos , Feminino , Insuficiência Ovariana Primária/genética , Fator 9 de Diferenciação de Crescimento/genética , Adulto , Mutação da Fase de Leitura , Mutação de Sentido Incorreto , Sequenciamento de Nucleotídeos em Larga Escala , Predisposição Genética para Doença , Estudos de Coortes , Genes RecessivosRESUMO
Gene therapy is a promising approach for hereditary deafness. We recently showed that unilateral AAV1-hOTOF gene therapy with dual adeno-associated virus (AAV) serotype 1 carrying human OTOF transgene is safe and associated with functional improvements in patients with autosomal recessive deafness 9 (DFNB9). The protocol was subsequently amended and approved to allow bilateral gene therapy administration. Here we report an interim analysis of the single-arm trial investigating the safety and efficacy of binaural therapy in five pediatric patients with DFNB9. The primary endpoint was dose-limiting toxicity at 6 weeks, and the secondary endpoint included safety (adverse events) and efficacy (auditory function and speech perception). No dose-limiting toxicity or serious adverse event occurred. A total of 36 adverse events occurred. The most common adverse events were increased lymphocyte counts (6 out of 36) and increased cholesterol levels (6 out of 36). All patients had bilateral hearing restoration. The average auditory brainstem response threshold in the right (left) ear was >95 dB (>95 dB) in all patients at baseline, and the average auditory brainstem response threshold in the right (left) ear was restored to 58 dB (58 dB) in patient 1, 75 dB (85 dB) in patient 2, 55 dB (50 dB) in patient 3 at 26 weeks, and 75 dB (78 dB) in patient 4 and 63 dB (63 dB) in patient 5 at 13 weeks. The speech perception and the capability of sound source localization were restored in all five patients. These results provide preliminary insights on the safety and efficacy of binaural AAV gene therapy for hereditary deafness. The trial is ongoing with longer follow-up to confirm the safety and efficacy findings. Chinese Clinical Trial Registry registration: ChiCTR2200063181 .
Assuntos
Dependovirus , Terapia Genética , Humanos , Terapia Genética/métodos , Criança , Masculino , Feminino , Dependovirus/genética , Pré-Escolar , Surdez/genética , Surdez/terapia , Adolescente , Resultado do Tratamento , Genes Recessivos , Vetores Genéticos/genética , Potenciais Evocados Auditivos do Tronco EncefálicoRESUMO
BACKGROUND: Steroid-resistant nephrotic syndrome is the second leading cause of chronic kidney disease among patients < 25 years of age. Through exome sequencing, identification of > 65 monogenic causes has revealed insights into disease mechanisms of nephrotic syndrome (NS). METHODS: To elucidate novel monogenic causes of NS, we combined homozygosity mapping with exome sequencing in a worldwide cohort of 1649 pediatric patients with NS. RESULTS: We identified homozygous missense variants in MYO1C in two unrelated children with NS (c.292C > T, p.R98W; c.2273 A > T, p.K758M). We evaluated publicly available kidney single-cell RNA sequencing datasets and found MYO1C to be predominantly expressed in podocytes. We then performed structural modeling for the identified variants in PyMol using aligned shared regions from two available partial structures of MYO1C (4byf and 4r8g). In both structures, calmodulin, a common regulator of myosin activity, is shown to bind to the IQ motif. At both residue sites (K758; R98), there are ion-ion interactions stabilizing intradomain and ligand interactions: R98 binds to nearby D220 within the myosin motor domain and K758 binds to E14 on a calmodulin molecule. Variants of these charged residues to non-charged amino acids could ablate these ionic interactions, weakening protein structure and function establishing the impact of these variants. CONCLUSION: We here identified recessive variants in MYO1C as a potential novel cause of NS in children.
Assuntos
Sequenciamento do Exoma , Mutação de Sentido Incorreto , Miosina Tipo I , Síndrome Nefrótica , Humanos , Miosina Tipo I/genética , Miosina Tipo I/química , Síndrome Nefrótica/genética , Masculino , Feminino , Criança , Homozigoto , Proteinúria/genética , Genes Recessivos , Pré-Escolar , Adolescente , Podócitos/metabolismo , Modelos MolecularesRESUMO
BACKGROUND: Leber hereditary optic neuropathy (LHON) is an inherited progressive optic neuropathy usually caused by mitochondrial DNA mutations. Recently, autosomal recessive (arLHON), which is caused by biallelic mutations in the DNAJC30 gene (usually c.152A > G), has been described. The onset of LHON before the age of 12 is uncommon and it is typically associated with a more variable clinical course and a more favorable visual prognosis than adult-onset LHON. MATERIALS AND METHODS: Detailed clinical findings of a female child with vision loss due to arLHON together with choroideremia (CHM) carrier state are presented. RESULTS: Genetic testing for the three most common mitochondrial LHON pathogenic variants was negative. On suspicion of arLHON, genetic testing was continued with the next-generation sequencing (NGS) of the nuclear DNA, identifying a homozygous pathogenic variant in DNAJC3°c.152A > G, p.(Tyr51Cys), but no alterations in the CHM gene. Idebenone treatment was started 4.5 months after the first evaluation. Clinical diagnosis of the CHM carrier state was confirmed by multiplex ligation-dependent probe amplification (MLPA) assay, which revealed a heterozygous deletion of all exons of the CHM. CONCLUSIONS: In children with acute or subacute, simultaneous, or sequential vision loss that is unresponsive to immunomodulatory treatment, LHON should be considered as a possible diagnosis. Our case emphasizes the diagnostic advantage of sequencing DNAJC30 in parallel with the mitochondrial DNA, especially in Eastern European descent patients. Genomic rearrangement testing should be considered for patients with a CHM carrier phenotype who have negative results on sequencing tests.
Assuntos
Coroideremia , DNA Mitocondrial , Atrofia Óptica Hereditária de Leber , Humanos , Atrofia Óptica Hereditária de Leber/genética , Atrofia Óptica Hereditária de Leber/diagnóstico , Atrofia Óptica Hereditária de Leber/tratamento farmacológico , Feminino , Coroideremia/genética , Coroideremia/diagnóstico , DNA Mitocondrial/genética , Acuidade Visual/fisiologia , Análise Mutacional de DNA , Mutação , Heterozigoto , Criança , Proteínas de Choque Térmico HSP40/genética , Tomografia de Coerência Óptica , Genes Recessivos , Testes Genéticos , Campos Visuais/fisiologiaRESUMO
Background: The identification and analysis of allelic variation are important bases for crop diversity research, trait domestication and molecular marker development. Grain tannin content is a very important quality trait in sorghum. Higher tannin levels in sorghum grains are usually required when breeding varieties resistant to bird damage or those used for brewing liquor. Non-tannin-producing or low-tannin-producing sorghum accessions are commonly used for food and forage. Tan1 and Tan2, two important cloned genes, regulate tannin biosynthesis in sorghum, and mutations in one or two genes will result in low or no tannin content in sorghum grains. Even if sorghum accessions contain dominant Tan1 and Tan2, the tannin contents are distributed from low to high, and there must be other new alleles of the known regulatory genes or new unknown genes contributing to tannin production. Methods: The two parents 8R306 and 8R191 did not have any known recessive alleles for Tan1 and Tan2, and it was speculated that they probably both had dominant Tan1 and Tan2 genotypes. However, the phenotypes of two parents were different; 8R306 had tannins and 8R191 had non-tannins in the grains, so these two parents were constructed as a RIL population. Bulked segregant analysis (BSA) was used to determine other new alleles of Tan1 and Tan2 or new Tannin locus. Tan1 and Tan2 full-length sequences and tannin contents were detected in wild sorghum resources, landraces and cultivars. Results: We identified two novel recessive tan1-d and tan1-e alleles and four recessive Tan2 alleles, named as tan2-d, tan2-e, tan2-f, and tan2-g. These recessive alleles led to loss of function of Tan1 and Tan2, and low or no tannin content in sorghum grains. The loss-of-function alleles of tan1-e and tan2-e were only found in Chinese landraces, and other alleles were found in landraces and cultivars grown all around the world. tan1-a and tan1-b were detected in foreign landraces, Chinese cultivars and foreign cultivars, but not in Chinese landraces. Conclusion: These results implied that Tan1 and Tan2 recessive alleles had different geographically distribution in the worldwide, but not all recessive alleles had been used in breeding. The discovery of these new alleles provided new germplasm resources for breeding sorghum cultivars for food and feed, and for developing molecular markers for low-tannin or non-tannin cultivar-assisted breeding in sorghum.
Assuntos
Alelos , Sorghum , Taninos , Genes de Plantas/genética , Genes Recessivos/genética , Fenótipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sorghum/genética , Sorghum/metabolismo , Taninos/genética , Taninos/metabolismoRESUMO
Epidermolysis bullosa (EB) is an umbrella term for a group of rare inherited skin disorders characterised by mucocutaneous fragility. Patients suffer from blisters and chronic wounds that arise spontaneously or following minor mechanical trauma, often resulting in inflammation, scarring and fibrosis due to poor healing. The recessive form of dystrophic EB (RDEB) has a particularly severe phenotype and is caused by mutations in the COL7A1 gene, encoding the collagen VII protein, which is responsible for adhering the epidermis and dermis together. One of the most feared and devastating complications of RDEB is the development of an aggressive form of cutaneous squamous cell carcinoma (cSCC), which is the main cause of mortality in this patient group. However, pathological drivers behind the development and progression of RDEB-associated cSCC (RDEB-cSCC) remain somewhat of an enigma, and the evidence to date points towards a complex process. Currently, there is no cure for RDEB-cSCC, and treatments primarily focus on prevention, symptom management and support. Therefore, there is an urgent need for a comprehensive understanding of this cancer's pathogenesis, with the aim of facilitating the discovery of drug targets. This review explores the current knowledge of RDEB-cSCC, emphasising the important role of the immune system, genetics, fibrosis, and the tumour-promoting microenvironment, all ultimately intricately interconnected.