RESUMO
BACKGROUND: LCAT (lecithin-cholesterol acyltransferase) deficiency is characterized by two distinct phenotypes, familial LCAT deficiency (FLD) and Fish Eye disease (FED). This is the first systematic review evaluating the ethnic distribution of LCAT deficiency, with particular emphasis on Latin America and the discussion of three Mexican-Mestizo probands. METHODS: A systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic review and Meta-Analysis) Statement in Pubmed and SciELO. Articles which described subjects with LCAT deficiency syndromes and an assessment of the ethnic group to which the subject pertained, were included. RESULTS: The systematic review revealed 215 cases (154 FLD, 41 FED and 20 unclassified) pertaining to 33 ethnic/racial groups. There was no association between genetic alteration and ethnicity. The mean age of diagnosis was 42 ± 16.5 years, with fish eye disease identified later than familial LCAT deficiency (55 ± 13.8 vs. 41 ± 14.7 years respectively). The prevalence of premature coronary heart disease was significantly greater in FED vs. FLD. In Latin America, 48 cases of LCAT deficiency have been published from six countries (Argentina (1 unclassified), Brazil (38 FLD), Chile (1 FLD), Columbia (1 FLD), Ecuador (1 FLD) and Mexico (4 FLD, 1 FED and 1 unclassified). Of the Mexican probands, one showed a novel LCAT mutation. CONCLUSIONS: The systematic review shows that LCAT deficiency syndromes are clinically and genetically heterogeneous. No association was confirmed between ethnicity and LCAT mutation. There was a significantly greater risk of premature coronary artery disease in fish eye disease compared to familial LCAT deficiency. In FLD, the emphasis should be in preventing both cardiovascular disease and the progression of renal disease, while in FED, cardiovascular risk management should be the priority. The LCAT mutations discussed in this article are the only ones reported in the Mexican- Amerindian population.
Assuntos
Etnicidade/genética , Deficiência da Lecitina Colesterol Aciltransferase/etnologia , Etnicidade/estatística & dados numéricos , Predisposição Genética para Doença/etnologia , Predisposição Genética para Doença/genética , Humanos , Indígenas Norte-Americanos/genética , Indígenas Norte-Americanos/estatística & dados numéricos , Deficiência da Lecitina Colesterol Aciltransferase/genética , México , Fosfatidilcolina-Esterol O-Aciltransferase/genética , Grupos Raciais/genética , Grupos Raciais/estatística & dados numéricosRESUMO
INTRODUÇÃO: Os níveis de colesterol ligados à lipoproteína de alta densidade (HDL-c) estão inversamente associados a elevado risco de doenças cardiovasculares (DCV). Dentre as causas de baixos níveis de HDL-c está a deficiência familiar de lecitina-colesterol aciltransferase (LCAT), enzima responsável pela esterificação do colesterol livre na superfície de lipoproteínas; sua deficiência leva ao rápido catabolismo das apolipoproteínas AI e AII, principais constituintes do HDL. Existem duas formas de déficit de LCAT: familiar, caracterizada por opacidades corneanas, anemia hemolítica e insuficiência renal; e doença olho de peixe, quando ocorre em homozigose, cursando com baixos níveis de HDL-c, nefropatia e opacidades em córneas. A doença coronariana geralmente não faz parte do fenótipoda síndrome do olho de peixe, mas pode ocorrer em algumas mutações, mesmo em heterozigotos. MÉTODOS: Realizada pesquisa em SciELO e PubMed sobre o tema e revisão de prontuário. RESULTADOS (RELATO): Paciente 35 anos, feminino, com antecedentes de nefrolitíase e depressão, encaminhada para hospital terciário de cardiologia para investigação de síncope. Exame físico inicial evidenciou arcos corneanos bilaterais, sem outros achados. Tilt Test positivo para síncope cardioinibitória. Para investigação de achado em exame físico foram solicitados exames laboratoriais, sendo evidenciados colesterol total = 61, HDL-c=05 e LDL-c=44. Realizou tomografia para avaliação de escore de cálcio, com resultado normal. Fundo de olho documentou arco corneano em ambos os olhos e Van Herick IV bilateral (figura 1), sugerindo doença do olho de peixe. Em teste genético foi evidenciado variante no gene da LCAT, com troca de Arginina por Histidina na posição 246 (Arg246His), previamente associada a HDL-c baixo em famílias italiana e portuguesa, levando a um fenótipo similar à doença do olho de peixe, em geral não associado a DCV. Paciente mantém seguimento ambulatorial, sem evidências clínicas ou subclínicas de aterosclerose ou eventos cardiovasculares até o momento, função renal e acuidade visual normais. CONCLUSÃO: A doença do olho de peixe e suas variantes são raras e caracterizam-se por níveis extremamente baixos de HDL-c. O impacto quanto à elevação do risco cardiovascular ainda não é consenso na literatura. O diagnóstico torna-se importante para a pesquisa de aterosclerose subclínica, identificação e tratamento complicações e pesquisa da doença em familiares. No caso relatado, paciente diagnosticada com variante de doença do olho de peixe, sem evidências de aterosclerose até o momento.
Assuntos
Genética , Deficiência da Lecitina Colesterol AciltransferaseRESUMO
BACKGROUND: Lecithin-cholesterol acyltransferase (LCAT) is a plasma enzyme that esterifies cholesterol in high- and low-density lipoproteins (HDL and LDL). Mutations in LCAT gene causes familial LCAT deficiency, which is characterized by very low plasma HDL-cholesterol levels (Hypoalphalipoproteinemia), corneal opacity and anemia, among other lipid-related traits. Our aim is to evaluate clinical/biochemical features of a Chilean family with a proband showing clinical signs of familial LCAT deficiency, as well as to identify and assess the functional effects of LCAT mutations. METHODS: An adult female proband with hypoalphalipoproteinemia, corneal opacity and mild anemia, as well as her first-degree relatives, were recruited for clinical, biochemical, genetic, in-silico and in-vitro LCAT analysis. Sequencing of exons and intron-exon boundaries was performed to identify mutations. Site-directed mutagenesis was carried out to generate plasmids containing cDNA with wild type or mutant sequences. Such expression vectors were transfected to HEK-239 T cells to asses the effect of LCAT variants in expression, synthesis, secretion and enzyme activity. In-silico prediction analysis and molecular modeling was also used to evaluate the effect of LCAT variants. RESULTS: LCAT sequencing identified rare p.V333 M and p.M404 V missense mutations in compound heterozygous state in the proband, as well the common synonymous p.L363 L variant. LCAT protein was detected in proband's plasma, but with undetectable enzyme activity compared to control relatives. HEK-293 T transfected cells with vector expression plasmids containing either p.M404 V or p.V333 M cDNA showed detectable LCAT protein expression both in supernatants and lysates from cultured cells, but with much lower enzyme activity compared to cells transfected with the wild-type sequence. Bioinformatic analyses also supported a causal role of such rare variations in LCAT lack of function. Additionally, the proband carried the minor allele of the synonymous p.L363 L variant. However, this variant is unlikely to affect the clinical phenotype of the proband given its relatively high frequency in the Chilean population (4%) and its small putative effect on plasma HDL-cholesterol levels. CONCLUSION: Genetic, biochemical, in vitro and in silico analyses indicate that the rare mutations p.M404 V and p.V333 M in LCAT gene lead to suppression of LCAT enzyme activity and cause clinical features of familial LCAT deficiency.
Assuntos
Hipoalfalipoproteinemias/genética , Deficiência da Lecitina Colesterol Aciltransferase/genética , Lipídeos/sangue , Fosfatidilcolina-Esterol O-Aciltransferase/genética , Adulto , Idoso , Chile/epidemiologia , Colesterol/sangue , HDL-Colesterol/sangue , Opacidade da Córnea/genética , Opacidade da Córnea/patologia , Éxons/genética , Feminino , Células HEK293 , Humanos , Hipoalfalipoproteinemias/sangue , Hipoalfalipoproteinemias/epidemiologia , Hipoalfalipoproteinemias/patologia , Deficiência da Lecitina Colesterol Aciltransferase/sangue , Deficiência da Lecitina Colesterol Aciltransferase/epidemiologia , Deficiência da Lecitina Colesterol Aciltransferase/patologia , Lipoproteínas HDL/sangue , Simulação de Dinâmica Molecular , Mutação de Sentido Incorreto/genética , Linhagem , Fosfatidilcolina-Esterol O-Aciltransferase/química , Relação Estrutura-AtividadeRESUMO
PURPOSE: To present ocular findings and anterior segment-optical coherence tomography (AS-OCT) imaging findings of 2 cases of fish-eye disease (FED) involving 2 novel genetic variants of the lecithin-cholesterol acyltransferase (LCAT) gene. METHODS: A case report. RESULTS: A 46-year-old woman and 63-year-old man presented with blurred vision, burning sensation, and whitening of both eyes for 2 and 3 years, respectively. Ophthalmologic examination revealed slightly decreased visual acuity, yellowish-white diffuse corneal opacities causing corneal clouding, and dry eye disease bilaterally in both patients. AS-OCT imaging demonstrated diffuse hyperreflective corneal opacities predominantly located in the anterior stroma. On systemic examination, both patients had very low plasma high-density lipoprotein cholesterol levels. However, they did not have any systemic associations with familial LCAT deficiency or Tangier disease, which are differential diagnoses for corneal clouding and low plasma high-density lipoprotein cholesterol. Both patients were diagnosed with FED based on clinical findings. Furthermore, genetic analysis, in which novel variants of c.86A>G (p.Asn29Ser) in the first exon and c.1052A>G (p.Tyr351Cys) in the sixth exon on the LCAT gene were detected, confirmed the diagnosis. CONCLUSIONS: Although it is a rare genetic disorder, FED should be considered in the differential diagnosis of corneal clouding. Corneal lipid deposits, visible on AS-OCT are suggestive of FED, and genetic analysis can be used to confirm the clinical diagnosis. Finally, there may be a relationship between dry eye disease and LCAT enzyme deficiency disorders, which should be investigated in further studies.
Assuntos
Opacidade da Córnea/diagnóstico , Deficiência da Lecitina Colesterol Aciltransferase/diagnóstico , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Fosfatidilcolina-Esterol O-Aciltransferase/genéticaRESUMO
This syndrome is a pathological entity of low incidence which mainly affects high density lipoprotein (HDL) metabolism. We here show the first case reported in our country, observed in a 63-year-old woman who showed bilateral corneal opacity and eruptive xanthomas in both arms. The lipoprotein profile disclosed severe hypertriglyceridemia and normocholesterolemia, although the percentage of cholesteryl esters was low. Plasma levels of HDL-cholesterol and HDL major apolipoproteins, A-I and A-II, were markedly decreased. The patient also showed glucose intolerance and hematological alterations related to abnormal lipid composition of erythrocyte membranes. As evaluated by the exogen substrate method, LCAT activity proved to be 82% lower in the patient than in a control subject. It is noteworthy that the patient had experienced cardiac events and presented hypertension, neither of which has been commonly documented in partial LCAT deficiency syndromes.
Assuntos
HDL-Colesterol/sangue , Deficiência da Lecitina Colesterol Aciltransferase/sangue , Feminino , Fenofibrato/uso terapêutico , Humanos , Deficiência da Lecitina Colesterol Aciltransferase/diagnóstico , Deficiência da Lecitina Colesterol Aciltransferase/tratamento farmacológico , Pessoa de Meia-Idade , SíndromeRESUMO
El síndrome de deficiencia parcial de la enzima lecitina-colesterol aciltransferasa (LCAT) es una en tidad patológica de baja incidencia que afecta fundamentalmente el metabolismo de las lipoproteínas de alta densidad (HDL). Comunicamos el primer caso reportado en nuestro país. Se presentó en una mujer de 63 años de edad que tenía opacidad corneal bilateral y xantomas eruptivos en brazos y antebrazos. El estudio lipoproteico reveló hipertrigliceridemia severa t colesterolemia normal, aunque la proporción de colesterol esterificado se hallaba substancialmente disminuida. Es de notar que los niveles plasmáticos de colesterol-HDL y de sus apoproteínas mayoritarias, A-I y A-IIm fueron insualmente bajos. Se observó además intolerancia a la glucosa y alteraciones hematológicas relacionadas con una composición lipídica anormal de las membranas eritrocitarias. La actividad plasmática de la LCAT, evaluada por el método del sustrato exógeno, fue un 82 por ciento menor en la paciente que en un individuo control. Es de destacar que la paciente aquí descripta mostró antecedentes de episodios cardíacos e hipertensión arterial, lo cual difere de muchos de los casos de deficiencia parcial de la enzima (LCAT).
Assuntos
Pessoa de Meia-Idade , Feminino , Humanos , HDL-Colesterol/sangue , Deficiência da Lecitina Colesterol Aciltransferase/sangue , Fenofibrato/uso terapêutico , Deficiência da Lecitina Colesterol Aciltransferase/complicações , Deficiência da Lecitina Colesterol Aciltransferase/diagnóstico , Deficiência da Lecitina Colesterol Aciltransferase/tratamento farmacológico , SíndromeRESUMO
El síndrome de deficiencia parcial de la enzima lecitina-colesterol aciltransferasa (LCAT) es una en tidad patológica de baja incidencia que afecta fundamentalmente el metabolismo de las lipoproteínas de alta densidad (HDL). Comunicamos el primer caso reportado en nuestro país. Se presentó en una mujer de 63 años de edad que tenía opacidad corneal bilateral y xantomas eruptivos en brazos y antebrazos. El estudio lipoproteico reveló hipertrigliceridemia severa t colesterolemia normal, aunque la proporción de colesterol esterificado se hallaba substancialmente disminuida. Es de notar que los niveles plasmáticos de colesterol-HDL y de sus apoproteínas mayoritarias, A-I y A-IIm fueron insualmente bajos. Se observó además intolerancia a la glucosa y alteraciones hematológicas relacionadas con una composición lipídica anormal de las membranas eritrocitarias. La actividad plasmática de la LCAT, evaluada por el método del sustrato exógeno, fue un 82 por ciento menor en la paciente que en un individuo control. Es de destacar que la paciente aquí descripta mostró antecedentes de episodios cardíacos e hipertensión arterial, lo cual difere de muchos de los casos de deficiencia parcial de la enzima (LCAT). (AU)
Assuntos
Pessoa de Meia-Idade , Feminino , Humanos , Deficiência da Lecitina Colesterol Aciltransferase/sangue , HDL-Colesterol/sangue , Síndrome , Fenofibrato/uso terapêutico , Deficiência da Lecitina Colesterol Aciltransferase/complicações , Deficiência da Lecitina Colesterol Aciltransferase/diagnóstico , Deficiência da Lecitina Colesterol Aciltransferase/tratamento farmacológicoRESUMO
Familial and secondary deficiency of plasma lecithin-cholesterol acyltransferase (LCAT) produce circulating lipoprotein particles with gross structural and compositional abnormalities; these have adverse effects on a variety of cellular functions. Factors affecting hepatic synthesis and secretion of this plasma enzyme are largely unknown but, potentially, some of them can be investigated with monospecific antibodies. In the present study, enzymically active LCAT was purified 40,000-fold from human plasma and then used to raise polyclonal antibodies in New Zealand White rabbits. Addition of this antiserum (1 microliter) to human plasma (25 microlitres) completely inhibited LCAT activity, although it was less effective against plasma from other species. The antibodies appeared to be monospecific to plasma LCAT. They gave a single precipitin arc by crossed immunoelectrophoresis, while immunodiffusion established that there was no cross-reactivity with several apolipoproteins or with serum albumin. Moreover, the antiserum was successfully used to detect LCAT in normal human plasma by Laurell rocket immunoelectrophoresis. By contrast, Western blotting of plasma proteins using whole LCAT antiserum was largely unsuccessful because of high background staining, although this could be substantially reduced by use of an IgG fraction. However, the whole antiserum readily immunoprecipitated LCAT secreted into the culture medium of HepG2 cells, a human hepatoblastoma cell line, pre-labelled with [35S]methionine, the [35S]-labelled LCAT appearing as a narrow 65-kDa protein band by electrophoresis and fluorography. We conclude that polyclonal antibodies may be an important tool to investigate the characteristics and underlying mechanisms of secondary LCAT deficiencies, including those associated with hepatic cirrhosis and schistosomiasis.
Assuntos
Anticorpos/imunologia , Fosfatidilcolina-Esterol O-Aciltransferase/imunologia , Animais , Proteínas Sanguíneas/análise , Western Blotting , Humanos , Imunoensaio , Imunodifusão , Imunoeletroforese , Deficiência da Lecitina Colesterol Aciltransferase/imunologia , Fosfatidilcolina-Esterol O-Aciltransferase/sangue , CoelhosRESUMO
Familial and secondary deficiency of plasma lecithin-cholesterol acyltransferase (LCAT) produce circulating lipoprotein particles with gross structural and compositional abnormalities; these have adverse effects on a variety of cellular functions. Factors affecting hepatic synthesis and secretion of this plasma enzyme are largely unknown but, potentially, some of them can be investigated with monospecific antibodies. In the present study, enzymically active LCAT was purified 40,000-fold from human plasma and then used to raise polyclonal antibodies in New Zealand White rabbits. Addition of this antiserum (1 mul) to human plasma (25 mul) completely inhibited LCAT activity, although it was less effective against plasma from other species. The antibodies appeared to be monospecific to plasma LCAT. They gave a single precipitin arc by crossed immunoelectrophoresis, while immunodiffusion established that there was no cross-reactivity with several apolipoproteins or with serum albumin. Moreover, the antiserum was successfully used to detect LCAT in normal human plasma by Laurell rocket immunoelectrophoresis. By contrast, Western blotting of plasma proteins using whole LCAT antiserum was largely unsuccessful because of high background staining, although this could be substantially reduced by use of an IgG fraction. However, the whole antiserum readily immunoprecipitated LCAT secreted into the culture medium of HepG2 cells, a human hepatoblastoma cell line, pre-labelled with [35S]methionine, the [(35)S]-labelled LCAT appearing as a narrow 65-kDa protein band by electrophoresis and fluorography. We conclude that polyclonal antibodies may be an important tool to investigate the characteristics and underlying mechanisms of secondary LCAT deficiencies, including those associated with hepatic cirrhosis and schistosomiasis.
Assuntos
Humanos , Anticorpos/administração & dosagem , Proteínas Sanguíneas/análise , Fosfatidilcolina-Esterol O-Aciltransferase/análise , Fosfatidilcolina-Esterol O-Aciltransferase/imunologia , Western Blotting , Imunoeletroforese Bidimensional , Deficiência da Lecitina Colesterol Aciltransferase/imunologia , Deficiência da Lecitina Colesterol Aciltransferase/patologiaRESUMO
Plasma lipids, lecithin:cholesterol acyltransferase (LCAT) activity and erythrocyte lipid composition were compared for a group of newly diagnosed uraemic patients and a group of healthy subjects. Plasma triacylglycerol was increased and both total and high-density lipoprotein (HDL) cholesterol were decreased. A lower percentage of total cholesterol in patients' plasma was in the esterified form and plasma values of the phospholipid, lysolecithin, were also lower. The plasma LCAT activity of uraemic patients, whether expressed as nmol or percentage of cholesterol esterified per hour, was significantly lower than for normals. Both LCAT activity and lysolecithin in uraemic plasma were inversely correlated with the concentration of urea. The lipid composition of erythrocytes from patients was also abnormal, with both free cholesterol and lecithin being increased. These results are consistent with the occurrence of an acquired deficiency of LCAT in uraemia, comparable to that previously described in hepatic disease. The LCAT enzyme is secreted by the liver, and the inverse correlation noted in this study between LCAT activity and urea suggests that the increased urea in renal disease may inhibit the synthesis and secretion of the enzyme by the liver. The resulting reduction in LCAT activity may lead to the accumulation of cholesterol and lecithin in cell membranes and contribute to the overall pathophysiology of renal disease.