RESUMO
Sitosterolemia is an autosomal recessive and very rare disease. Its main characteristic is that there is a greater absorption and a decrease in the excretion of sterols, which leads to them being deposited in tissues. It is given by mutations in the ABCG5 or ABCG8 genes found on chromosome 2p21. In this clinical note, we describe the first two patients with familial sitosterolemia described in Colombia, brothers, one of them with xanthomas in extremities as the only symptom, and the other, completely asymptomatic. Genetic studies were performed as a diagnostic test in both patients, where a pathogenic homozygous variant could be identified in the ABCG8 gene in the first case (symptomatic), and a heterozygous variant in the ABCG8 gene in the second case (asymptomatic); the first patient has responded to treatment with ezetimibe. In conclusion, xanthomas should be studied in depth in pediatric age as they may be the only visible sign of such complex and hereditary diseases as familial sitosterolemia, which can be controlled and prevent cardiovascular complications of the disease.
Assuntos
Membro 8 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Ezetimiba , Hipercolesterolemia , Enteropatias , Erros Inatos do Metabolismo Lipídico , Fitosteróis , Humanos , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/diagnóstico , Masculino , Colômbia , Fitosteróis/efeitos adversos , Fitosteróis/genética , Enteropatias/genética , Enteropatias/diagnóstico , Membro 8 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Hipercolesterolemia/genética , Hipercolesterolemia/tratamento farmacológico , Hipercolesterolemia/diagnóstico , Ezetimiba/uso terapêutico , Xantomatose/genética , Xantomatose/patologia , Xantomatose/diagnóstico , Anticolesterolemiantes/uso terapêutico , Anticolesterolemiantes/administração & dosagem , Mutação , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Homozigoto , Criança , Heterozigoto , Lipoproteínas/genéticaRESUMO
PURPOSE OF REVIEW: The purpose of this review was to summarize important and updated information on sitosterolemia. Sitosterolemia is an inherited lipid disorder consisting of high levels of plasma plant sterols. This sterol storage condition is caused by biallelic loss-of-function genetic variants in either ABCG5 or ABCG8, leading to increased intestinal absorption and decreased hepatic excretion of plant sterols. Clinically, patients with sitosterolemia usually exhibit xanthomatosis, high levels of plasma cholesterol, and premature atherosclerotic disease, but presentation can be highly heterogeneous. Therefore, recognition of this condition requires a high level of suspicion, with confirmation upon genetic diagnosis or through measurement of plasma phytosterols. Treatment of sitosterolemia with both a plant sterol-restricted diet and the intestinal cholesterol absorption inhibitor ezetimibe can reduce efficiently the levels of plasma plant sterols, consisting in the first-line therapy for this disease. RECENT FINDINGS: Since hypercholesterolemia is often present in individuals with sitosterolemia, it is important to search for genetic variants in ABCG5 and ABCG8 in patients with clinical criteria for familial hypercholesterolemia (FH), but no variants in FH implicated genes. Indeed, recent studies have suggested that genetic variants in ABCG5/ABCG8 can mimic FH, and even when in heterozygosis, they may potentially exacerbate the phenotype of patients with severe dyslipidemia. Sitosterolemia is a genetic lipid disorder characterized by increased circulating levels of plant sterols and clinically manifested by xanthomatosis, hematologic disorders, and early atherosclerosis. Awareness about this condition, a rare, but commonly underdiagnosed and yet treatable cause of premature atherosclerotic disease, is imperative.
Assuntos
Aterosclerose , Hipercolesterolemia , Hiperlipoproteinemia Tipo II , Enteropatias , Erros Inatos do Metabolismo Lipídico , Fitosteróis , Xantomatose , Humanos , Hipercolesterolemia/tratamento farmacológico , Fitosteróis/efeitos adversos , Fitosteróis/genética , Erros Inatos do Metabolismo Lipídico/diagnóstico , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/terapia , Enteropatias/diagnóstico , Enteropatias/genética , Enteropatias/tratamento farmacológico , Hiperlipoproteinemia Tipo II/complicações , Colesterol , Xantomatose/etiologia , Aterosclerose/genética , Aterosclerose/complicaçõesRESUMO
Sitosterolemia is an autosomal recessive metabolic disease caused by mutations in ABCG5 or ABCG8 genes which encode for the (ATP)-binding cassette (ABC) transporters that are responsible for the trafficking of xenosterols. Liver involvement is not a recognized manifestation of this disease, and cirrhosis has been reported only once in the medical literature. We describe a fatal case of a 21-year old South Asian male who presented with decompensated cirrhosis, and biochemical abnormalities consistent with sitosterolemia. Genetic testing showed a homozygous pathogenic mutation in ABCG5, confirming the diagnosis. Sitosterolemia is a rare, but likely under-recognized condition, and a high degree of suspicion is imperative to make the diagnosis. We propose that sitosterolemia should be included in the differential diagnosis for patients with cryptogenic cirrhosis, especially as there are effective oral therapies to treat this condition. Newly diagnosed sitosterolemia patients should undergo a thorough hepatology evaluation and follow-up to evaluate for the presence, development, and progression of any hepatic involvement.
Assuntos
Hipercolesterolemia/complicações , Enteropatias/complicações , Erros Inatos do Metabolismo Lipídico/complicações , Cirrose Hepática/etiologia , Fitosteróis/efeitos adversos , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Anemia Hemolítica/etiologia , Anticolesterolemiantes/uso terapêutico , Biópsia , Angiografia Coronária , Doença da Artéria Coronariana/etiologia , Análise Mutacional de DNA , Dieta com Restrição de Gorduras , Ezetimiba/uso terapêutico , Evolução Fatal , Predisposição Genética para Doença , Hereditariedade , Homozigoto , Humanos , Hipercolesterolemia/diagnóstico , Hipercolesterolemia/genética , Hipercolesterolemia/terapia , Enteropatias/diagnóstico , Enteropatias/genética , Enteropatias/terapia , Erros Inatos do Metabolismo Lipídico/diagnóstico , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/terapia , Lipoproteínas/genética , Cirrose Hepática/diagnóstico , Masculino , Microscopia Eletrônica , Mutação , Linhagem , Fenótipo , Fitosteróis/genética , Fatores de Risco , Resultado do Tratamento , Xantomatose/etiologia , Adulto JovemRESUMO
Sitosterolemia is a disease characterized by an intestinal hyperabsorption of plant sterols and cholesterol. Affected individuals have mutations in both alleles of either ABCG5 or ABCG8 genes, leading to a total loss of one of the proteins and subsequent functional deficiency. We here report a Mexican family with clinical and biochemical features of sitosterolemia carrying 2 new mutations of the ABCG5 gene. Concentrations of sitosterol, campesterol, and cholesterol were found to be higher for the index case (a 10-year-old girl) than for her also affected sibling (64.1 vs 19 mg/dL, 32 vs 12.1 mg/dL, and cholesterol 295 vs 235 mg/dL, respectively). Both individuals showed 2 new ABCG5 gene mutations identified by sequencing, which is concordant with their biochemical diagnosis of sitosterolemia. The first mutation was a c.144 -1G>A transition that disrupts the intron 1 splicing acceptor site. The second mutation is the deletion c.1523 delC, which occurred in exon 11, causing an amino acid change at codon 510 (p.His510Thr) and a stop codon at codon 511 (p.Leu511X). The father is heterozygote for the mutation c.144 -1G>A, whereas the mother is heterozygote for the mutation c.1523 delC. In conclusion, we here report the first case of a Mexican family with sitosterolemia carrying two new ABCG5 gene mutations.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Hipercolesterolemia/genética , Enteropatias/genética , Erros Inatos do Metabolismo Lipídico/genética , Lipoproteínas/genética , Mutação , Linhagem , Fitosteróis/efeitos adversos , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Adolescente , Sequência de Bases , Criança , Feminino , Humanos , Masculino , México , Pessoa de Meia-Idade , Dados de Sequência Molecular , Fitosteróis/genética , Adulto JovemRESUMO
Este trabalho teve como objetivo estudar o polimorfismo Gln604Glu do gene ABCG5 e a sua correlação com os parâmetros lipídicos, em uma população de voluntários residentes na cidade de São Roque (SP), em 2009. Foram determinados os perfis lipídicos de 150 voluntários por meio de métodos enzimáticos colorimétricos (Advia-1650-Bayer) e em seguida a realização de análise do polimorfismo Gln604Glu do gene ABCG5 pela técnica de reação em cadeia da polimerase seguida de análise de enzima de restrição. Os resultados mostraram que 45% dos indivíduos apresentaram hipercolesterolemia, 31% exibiram hipertriacilglicerolemia e 11% hipoalfalipoproteinemia. A análise do polimorfismo Gln604Glu do gene ABCG5 demonstrou que 55% dos indivíduos eram heterozigotos, 37% homozigotos normais e 8% homozigotos mutantes. Não foi observada diferença significativa entre os perfis lipídicos dos homozigotos selvagens, homozigotos mutantes e heterozigotos, não existindo correlação entre os perfis lipídicos e o polimorfismo. Os resultados sugerem que na população estudada, a presença do polimorfismo não pode ser considerada como um biomarcador para dislipidemia. Sendo necessários estudos mais amplos que avaliem a relação entre o perfil genético do indivíduo e a resposta ao tratamento preconizado.
The aim of the present work is to study the Gln604Glu polymorphism of the ABCG5 gene and its correlation with the lipid profile in a volunteer population resident in the city of São Roque in the state of São Paulo (2009). For the analysis of the lipid profile and the Gln604Glu polymorphism, we used the techniques of colorimetric analysis, Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP), respectively. The results showed that 45% of the individuals presented with hypercholesterolemia, 31% with hypertriacylglyce-rolemia and 11% with hypoalphalipoproteinemia. The analysis of the Gln604Glu polymorphism showed that 55% of the individuals were heterozygous, 37% normal heterozygous and 8% mutant heterozygous. No significant difference was observed between the lipid profiles of the wild homozygous, mutant homozygous and heterozygous, there being no correlation between the lipid profile and polymorphisms. The results suggest that the presence of polymorphism cannot be used as a dyslipidemia biomarker, in the studied population. Broader studies are required that can evaluate the relationship between the genetic profile of the individual and the response to the advocated treatment.