RESUMO
Cardiomyopathy is a frequent complication of propionic acidemia (PA). It is often fatal, and its occurrence is largely independent of classic metabolic treatment modalities. Liver transplantation (LT) is a treatment option for severe PA as the liver plays a vital role in metabolism of the precursors that accumulate in patients with PA. LT in PA is now considered to be a long-lasting and valid treatment to prevent cardiac disease. The subject of this report had severe cardiomyopathy that largely disappeared prior to undergoing a LT. Three years following the transplant, there was recurrence of cardiomyopathy following a surgery that was complicated with a postoperative aspiration pneumonia. On his last hospital admission, he was presented with pulmonary edema and heart failure. He continued with episodes of intractable hypotension, despite maximum inotropic and diuretic support. He died following redirection of care. We conclude that lethal cardiomyopathy may develop several years after successful LT in patients with PA.
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Lesch-Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. Despite having been characterized over 50 years ago, it remains unclear precisely how deficits in HGprt enzyme activity can lead to the neurological syndrome, especially the self-injury of LND. Several studies have proposed different hypotheses regarding the etiology of this disease, and several treatments have been tried in patients. However, up to now, there is no satisfactory explanation of the disease and for many LND patients, efficacious treatment for persistent self-injurious behavior remains unreachable. A role for epistasis between mutated hypoxanthine phosphoribosyltransferase 1 (HPRT1) and amyloid precursor protein (APP) genes has been recently suggested. This finding may provide new directions not only for investigating the role of APP in neuropathology associated with HGprt-deficiency in LND but also for the research in neurodevelopmental and neurodegenerative disorders in which the APP gene is involved in the pathogenesis of diseases and may pave the way for new strategies applicable to rational antisense drugs design. It is therefore necessary to study the HGprt enzyme and APP using expression vectors for exploring their impacts on LND as well as other human diseases, especially the ones related to APP such as Alzheimer's disease in which the physiologic function and the structure of the entire APP remain largely unclear until now. For such a purpose, we report here the construction of expression vectors as the first step (Part I) of our investigation.
Assuntos
Precursor de Proteína beta-Amiloide/genética , Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/genética , Síndrome de Lesch-Nyhan/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Epigenômica , Regulação da Expressão Gênica , Células HEK293 , Humanos , Hipoxantina Fosforribosiltransferase/metabolismo , Mutação , Purinas/metabolismo , Proteína Carregadora de Folato Reduzido/genética , Proteína Carregadora de Folato Reduzido/metabolismo , TransfecçãoRESUMO
The product of thiamine phosphokinase is the cofactor for many enzymes, including the dehydrogenases of pyruvate, 2-ketoglutarate and branched chain ketoacids. Its deficiency has recently been described in a small number of patients, some of whom had a Leigh syndrome phenotype. The patient who also had a Leigh phenotype was initially found to have a low concentration of biotin in plasma and massive urinary excretion of biotin. Despite treatment with biotin and thiamine, her disease was progressive. Mutations c.311delG and c.426Gâ¯>â¯C were found in the TPK1 gene.
Assuntos
Doenças dos Gânglios da Base/genética , Biotina/uso terapêutico , Tiamina Pirofosfoquinase/deficiência , Tiamina Pirofosfoquinase/genética , Adulto , Doenças dos Gânglios da Base/metabolismo , Doenças dos Gânglios da Base/patologia , Biotina/sangue , Biotina/urina , Feminino , Humanos , Mutação , Fenótipo , Tiamina Pirofosfoquinase/metabolismo , Tiamina/uso terapêuticoRESUMO
Lesch-Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report a novel point mutation that led to HGprt-related neurological dysfunction (HND) in a family in which there was a missense mutation in exon 6 of the coding region of the HPRT1 gene: g.34938G>T, c.403G>T, p.D135Y. Molecular diagnosis is consistent with the genetic heterogeneity of the HPRT1 gene responsible for HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.
Assuntos
Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/enzimologia , Síndrome de Lesch-Nyhan/genética , Mutação de Sentido Incorreto , Sequência de Bases , Pré-Escolar , Éxons/genética , Feminino , Humanos , Hipoxantina Fosforribosiltransferase/metabolismo , Masculino , LinhagemRESUMO
Lesch-Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report two independent point mutations leading to splicing errors: IVS 2 +1G>A, c.134 +1G>A, and IVS 3 +1G>A, c.318 +1G>A in the hypoxanthine-phosphoribosyltransferase1 (HPRT1) gene which result in exclusion of exon 2 and exon 3 respectively, in the HGprt enzyme protein from different members of two Chiloé Island families. Molecular analysis has revealed the heterogeneity of genetic mutation of the HPRT1 gene responsible for the HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.
Assuntos
Hipoxantina Fosforribosiltransferase/genética , Ilhas , Síndrome de Lesch-Nyhan/enzimologia , Síndrome de Lesch-Nyhan/genética , Mutação , Linhagem , Adolescente , Adulto , Sequência de Bases , Chile , Éxons/genética , Feminino , Humanos , Masculino , Adulto JovemRESUMO
The present work is the development of a simple and specific kinetic method based on RT-PCR technique coupled with direct sequencing for quantification of various amyloid precursor protein-mRNA isoforms (APP-mRNA isoforms) in biological samples, especially for identifying the most abundant one that may decisive for the normal status or disease risk. Application of this kinetic method to the Lesch-Nyhan disease (LND) was performed and results indicated an epistasis between mutated hypoxanthine phosphoribosyltransferase1 (HPRT1) and APP genes. APP-mRNA isoform of 624bp, with a deletion starting after 49bp of the 5' end of exon 3 followed by a complete deletion of exons 4-15, mutations in exon 1: c.22C>T, p.L18F, and exon 3: c.269A>G, p.Q90R encoding APP207 isoform, was the most abundant one in most of the LND patients and would be responsible for the neurobehavioral syndrome in these patients. The method is useful for identifying the defective APP-mRNA isoform in LND patients, and in neurodevelopmental and neurodegenerative disorders in which the APP gene is involved in the pathogenesis of diseases such as autism, fragile X syndrome, amyotrophic lateral sclerosis, and Alzheimer's disease, and may pave the way for new strategies applicable to rational antisense drugs design.
Assuntos
Precursor de Proteína beta-Amiloide/genética , Epistasia Genética/genética , Predisposição Genética para Doença , Síndrome de Lesch-Nyhan/genética , Isoformas de RNA/metabolismo , Doença de Alzheimer/genética , Humanos , Hipoxantina Fosforribosiltransferase/genética , Mutação/genética , Doenças Neurodegenerativas/genética , Isoformas de Proteínas/genéticaRESUMO
Lesch-Nyhan disease (LND) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report three novel independent mutations in the coding region of the HPRT1 gene from genomic DNA of (a) a carrier sister of two male patients with LND: c.569G>C, p.G190A in exon 8; and (b) two LND affected male patients unrelated to her who had two mutations: c.648delC, p.Y216X, and c.653C>G, p.A218G in exon 9. Molecular analysis reveals the heterogeneity of genetic mutation of the HPRT1 gene responsible for the HGprt deficiency. It allows fast, accurate detection of carriers and genetic counseling.
Assuntos
Substituição de Aminoácidos , Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/genética , Adulto , Alanina , Pré-Escolar , Éxons , Feminino , Glicina , Heterozigoto , Humanos , Hipoxantina Fosforribosiltransferase/deficiência , Lactente , Masculino , MutaçãoRESUMO
We report a patient, an infant with a neurodevelopmental disorder manifesting intractable complex partial epilepsy, bull's eye maculopathy, microcephaly, bilateral cataracts, truncal hypotonia, and spasticity of all four extremities. Sequencing of genomic DNA revealed mutations in (a) exon 8 (Ox-2 antigen domain) of the amyloid precursor protein (APP) gene: c.1075C>T, p.Arg359* (b) exon 8 of the senataxin (SETX) gene: c.4738C>T, p.Arg1580Cys, and (c) exon 2 of the ceroid-lipofuscinosis, neuronal 8 (CLN8) gene: c.685C>G, p.Pro229Ala. Using a quantitative method for measurement of various APP-mRNA isoforms, we found that the APP-mRNA isoform of 624 bp with a deletion starting after 49 bp of the 5' end of exon 3 followed by a complete deletion of exons 4-15, mutations in exon 1: c.22C>T, p.L18F, and exon 3: c.269A>G, p.Q90R encoding APP207 isoform was the most abundant one, and would appear to be responsible for the clinical manifestations. This is the first example that may underline the role of the epigenetic regulation in the expression of APP gene leading to a neurodevelopmental disorder resulting from a nonsense mutation in the Ox-2 antigen domain.
Assuntos
Precursor de Proteína beta-Amiloide/genética , Epigênese Genética , Mutação , Transtornos do Neurodesenvolvimento/genética , Precursor de Proteína beta-Amiloide/química , Sequência de Bases , Pré-Escolar , Códon sem Sentido , Consanguinidade , Éxons , Feminino , Deleção de Genes , Humanos , Masculino , Linhagem , RNA Mensageiro/genéticaRESUMO
Objective Orotic aciduria and deficiency of uridine monophosphate synthetase have been observed in a patient, studied over 10 years, who had no megaloblastic anemia. Excretion of orotic acid and orotidine were 8.24 and 0.52 mmol/mol of creatinine. The ratio of 15.85 differed appreciably from that of 6 patients reported with no megaloblastic anemia. Methods The analysis of orotidine by gas chromotography mass spectrometry was conducted. Conclusion Patients with orotic aciduria with and without megaloblastic anemia cannot be distinguished by ratio of orotic acid to orotidine.
Assuntos
Orotato Fosforribosiltransferase/deficiência , Ácido Orótico/urina , Orotidina-5'-Fosfato Descarboxilase/deficiência , Erros Inatos do Metabolismo da Purina-Pirimidina/urina , Uridina/análogos & derivados , Criança , Feminino , Humanos , Orotato Fosforribosiltransferase/efeitos dos fármacos , Orotato Fosforribosiltransferase/urina , Orotidina-5'-Fosfato Descarboxilase/efeitos dos fármacos , Orotidina-5'-Fosfato Descarboxilase/urina , Uridina/uso terapêutico , Uridina/urina , Adulto JovemRESUMO
Lesch-Nyhan syndrome (LNS) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGprt) is defective. The authors report a novel mutation which led to HGprt-related neurological dysfunction (HND) in two brothers from the same family with a missense mutation in exon 6 of the coding region of the HPRT1 gene: c.437T>C, p.L146S. Molecular diagnosis discloses the genetic heterogeneity of the HPRT1 gene responsible for HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.
Assuntos
Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/genética , Adulto , Sequência de Bases , Análise Mutacional de DNA , Estudos de Associação Genética , Humanos , Síndrome de Lesch-Nyhan/diagnóstico , Masculino , Técnicas de Diagnóstico Molecular , Mutação de Sentido Incorreto , Mutação Puntual , Reação em Cadeia da PolimeraseRESUMO
Lesch-Nyhan disease (LND) is an inherited metabolic disorder characterized by the overproduction of uric acid and distinct behavioral, cognitive, and motor abnormalities. The most challenging clinical problem is self-injurious behavior (SIB), which includes self-biting, self-hitting, self-abrasion, and other features. Currently, these behaviors are managed by behavioral extinction, sedatives, physical restraints, and removal of teeth. More effective treatments are needed. Pre-clinical studies have led to the hypothesis that D1-dopamine receptor antagonists may provide useful treatments for SIB in LND. Ecopipam is one such selective D1-dopamine receptor antagonist. This report summarizes results of a dose-escalation study of the safety and tolerability of ecopipam in 5 subjects with LND. The results suggest that ecopipam is well tolerated, with sedation being the most common dose-limiting event. Several exploratory measures also suggest ecopipam might reduce SIB in this population. These results support the hypothesis that D1-dopamine receptor antagonists may be useful for suppressing SIB in LND, and encourage further studies of efficacy.
Assuntos
Benzazepinas/uso terapêutico , Antagonistas de Dopamina/uso terapêutico , Síndrome de Lesch-Nyhan/tratamento farmacológico , Receptores de Dopamina D1/antagonistas & inibidores , Adolescente , Adulto , Benzazepinas/administração & dosagem , Benzazepinas/efeitos adversos , Criança , Antagonistas de Dopamina/administração & dosagem , Antagonistas de Dopamina/efeitos adversos , Humanos , Síndrome de Lesch-Nyhan/diagnóstico , Síndrome de Lesch-Nyhan/metabolismo , Masculino , Pessoa de Meia-Idade , Comportamento Autodestrutivo , Resultado do Tratamento , Adulto JovemRESUMO
Hypoxanthine-guanine phosphoribosyl-transferase (HPRT) deficiency is the cause of Lesch-Nyhan disease. Adenine phosphoribosyl-transferase (APRT) deficiency causes renal calculi. The activity of each enzyme is readily determined on spots of whole blood on filter paper. This unit describes a method for detecting deficiencies of HPRT and APRT.
Assuntos
Adenina Fosforribosiltransferase/sangue , Ensaios Enzimáticos/métodos , Hipoxantina Fosforribosiltransferase/sangue , Síndrome de Lesch-Nyhan/sangue , Síndrome de Lesch-Nyhan/diagnóstico , Ensaios Enzimáticos/normas , Humanos , Controle de QualidadeRESUMO
Lesch-Nyhan syndrome (LNS) is a rare X-linked inherited neurogenetic disorder of purine metabolism in which the enzyme, hypoxanthine-guanine phosphoribosyltransferase(HGprt) is defective. The authors report a novel mutation which led to LNS in a family with a deletion followed by an insertion (INDELS) via the serial replication slippage mechanism: c.428_432delTGCAGinsAGCAAA, p.Met143Lysfs*12 in exon 6 of HPRT1 gene. Molecular diagnosis discloses the genetic heterogeneity of HPRT1 gene responsible for HGprt deficiency. It allows fast, accurate carrier detection and genetic counseling.
Assuntos
Hipoxantina Fosforribosiltransferase/genética , Mutação INDEL , Síndrome de Lesch-Nyhan/genética , Células Cultivadas , Família , Feminino , Humanos , MasculinoRESUMO
The drug nitisinone (NTBC) is used to treat tyrosinemia type I, and more recently has been also used for the treatment of another disorder of tyrosine metabolism, alkaptonuria. While studying the dose effects of NTBC treatment on alkaptonuria, untargeted metabolomics revealed perturbations in a completely separate pathway, that of tryptophan metabolism. Significant elevations in several indolic compounds associated with the indolepyruvate pathway of tryptophan metabolism were present in NTBC-treated patient sera and correlated with elevations of an intermediate of tyrosine metabolism. Indolic compounds of this pathway have long been associated with commensal bacterial and plant metabolism. These exogenous sources of indoles have been more recently implicated in affecting mammalian cell function and disease. We studied the correlation of these indolic compounds in other disorders of tyrosine metabolism including tyrosinemia types I and II as well as transient tyrosinemia, and demonstrated that 4-hydroxyphenylpyruvate (4-HPP) was directly responsible for the promotion of this pathway. We then investigated the regulation of the indolepyruvate pathway and the role of 4-HPP further in both mammalian cells and intestinal microbial cultures. We demonstrated that several of the indolic products, including indolepyruvate and indolelactate, were in fact generated by human cell metabolism, while the downstream indole metabolite, indolecarboxaldehyde, was produced exclusively by microbial cultures of human gut flora. This study describes a symbiotic perturbation in host and microbiome tryptophan metabolism in response to elevations related to defects of tyrosine metabolism and concomitant drug treatment.
Assuntos
Alcaptonúria/metabolismo , Cicloexanonas/uso terapêutico , Microbioma Gastrointestinal/fisiologia , Indóis/metabolismo , Nitrobenzoatos/uso terapêutico , Triptofano/metabolismo , Tirosina/metabolismo , Tirosinemias/metabolismo , Aldeídos/metabolismo , Alcaptonúria/sangue , Alcaptonúria/tratamento farmacológico , Linhagem Celular Tumoral , Humanos , Indóis/sangue , Espectrometria de Massas , Metabolômica , Ácidos Fenilpirúvicos/metabolismo , Simbiose , Tirosinemias/sangue , Tirosinemias/tratamento farmacológicoRESUMO
Alkaptonuria is an autosomal recessive disease involving a deficiency of the enzyme homogentisate dioxygenase, which is involved in the tyrosine degradation pathway. The enzymatic deficiency results in high concentrations of homogentisic acid (HGA), which results in orthopedic and cardiac complications, among other symptoms. Nitisinone (NTBC) has been shown to effectively treat alkaptonuria by blocking the conversion of 4-hydroxyphenylpyruvate to HGA, but there have been concerns that using doses higher than about 2 mg/day could cause excessively high levels of tyrosine, resulting in crystal deposition and corneal pathology. We have enrolled seven patients in a study to determine whether higher doses of NTBC were effective at further reducing HGA levels while maintaining tyrosine at acceptable levels. Patients were given varying doses of NTBC (ranging from 2 to 8 mg/day) over the course of between 0.5 and 3.5 years. Urine HGA, plasma tyrosine levels, and plasma NTBC were then measured longitudinally at various doses. We found that tyrosine concentrations plateaued and did not reach significantly higher levels as NTBC doses were increased above 2 mg/day, while a significant drop in HGA continued from 2 to 4 mg/day, with no significant changes at higher doses. We also demonstrated using untargeted metabolomics that elevations in tyrosine from treatment resulted in proportional elevations in alternative tyrosine metabolic products, that of N-acetyltyrosine and γ-glutamyltyrosine.
RESUMO
Establishing meaningful relationships between genetic variations and clinical disease is a fundamental goal for all human genetic disorders. However, these genotype-phenotype correlations remain incompletely characterized and sometimes conflicting for many diseases. Lesch-Nyhan disease is an X-linked recessive disorder that is caused by a wide variety of mutations in the HPRT1 gene. The gene encodes hypoxanthine-guanine phosphoribosyl transferase, an enzyme involved in purine metabolism. The fine structure of enzyme has been established by crystallography studies, and its function can be measured with very precise biochemical assays. This rich knowledge of genetic alterations in the gene and their functional effect on its protein product provides a powerful model for exploring factors that influence genotype-phenotype correlations. The present study summarizes 615 known genetic mutations, their influence on the gene product, and their relationship to the clinical phenotype. In general, the results are compatible with the concept that the overall severity of the disease depends on how mutations ultimately influence enzyme activity. However, careful evaluation of exceptions to this concept point to several additional genetic and non-genetic factors that influence genotype-phenotype correlations. These factors are not unique to Lesch-Nyhan disease, and are relevant to most other genetic diseases. The disease therefore serves as a valuable model for understanding the challenges associated with establishing genotype-phenotype correlations for other disorders.
Assuntos
Estudos de Associação Genética , Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/genética , Síndrome de Lesch-Nyhan/fisiopatologia , Mutação/genética , Animais , HumanosRESUMO
UNLABELLED: BACKGROUND, RATIONALE, AND METHODS: Lesch-Nyhan disease is a rare, X-linked disorder due to hypoxanthine phosphoribosyltransferase deficiency. To evaluate reported benefit on mood and behavior obtained by the administration of S-adenosyl-L-methionine in this condition, we developed 2 quantitative evaluation tools, and used them to assess the effects of the drug in our population: the weekly questionnaire and the resistance to self-injurious behavior test. We performed an open-label, dose-escalation trial of the drug on 14 patients. RESULTS: Four patients tolerated the drug and reported beneficial effects. The majority experienced worsened behavior. The 2 assessment tools demonstrated effectiveness in quantitatively evaluating the self-injurious behavior.
Assuntos
Afeto/efeitos dos fármacos , Comportamento/efeitos dos fármacos , Hipoxantina Fosforribosiltransferase/metabolismo , Síndrome de Lesch-Nyhan/tratamento farmacológico , S-Adenosilmetionina/farmacologia , S-Adenosilmetionina/uso terapêutico , Inquéritos e Questionários , Adolescente , Adulto , Criança , Relação Dose-Resposta a Droga , Humanos , Hipoxantina Fosforribosiltransferase/deficiência , Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/genética , Pessoa de Meia-Idade , Psicotrópicos/farmacologia , Psicotrópicos/uso terapêutico , Resultado do TratamentoRESUMO
Diabetic kidney disease is the leading cause of ESRD, but few biomarkers of diabetic kidney disease are available. This study used gas chromatography-mass spectrometry to quantify 94 urine metabolites in screening and validation cohorts of patients with diabetes mellitus (DM) and CKD(DM+CKD), in patients with DM without CKD (DM-CKD), and in healthy controls. Compared with levels in healthy controls, 13 metabolites were significantly reduced in the DM+CKD cohorts (P≤0.001), and 12 of the 13 remained significant when compared with the DM-CKD cohort. Many of the differentially expressed metabolites were water-soluble organic anions. Notably, organic anion transporter-1 (OAT1) knockout mice expressed a similar pattern of reduced levels of urinary organic acids, and human kidney tissue from patients with diabetic nephropathy demonstrated lower gene expression of OAT1 and OAT3. Analysis of bioinformatics data indicated that 12 of the 13 differentially expressed metabolites are linked to mitochondrial metabolism and suggested global suppression of mitochondrial activity in diabetic kidney disease. Supporting this analysis, human diabetic kidney sections expressed less mitochondrial protein, urine exosomes from patients with diabetes and CKD had less mitochondrial DNA, and kidney tissues from patients with diabetic kidney disease had lower gene expression of PGC1α (a master regulator of mitochondrial biogenesis). We conclude that urine metabolomics is a reliable source for biomarkers of diabetic complications, and our data suggest that renal organic ion transport and mitochondrial function are dysregulated in diabetic kidney disease.
Assuntos
Nefropatias Diabéticas/metabolismo , Metabolômica/métodos , Doenças Mitocondriais/etiologia , Adulto , Idoso , Feminino , Taxa de Filtração Glomerular , Humanos , Transporte de Íons , Masculino , Pessoa de Meia-Idade , Proteína 1 Transportadora de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Insuficiência Renal Crônica/metabolismo , Fatores de Transcrição/genéticaRESUMO
Inherited mutation of the purine salvage enzyme, hypoxanthine guanine phosphoribosyltransferase (HPRT) gives rise to Lesch-Nyhan syndrome (LNS) or Lesch-Nyhan variants (LNVs). We report three novel independent mutations in the coding region of HPRT gene: exon 3: c.141delA, p.D47fs53X; exon 5: c.400G>A, p.E134K; exon 7: c.499A>G, p.R167G from three LNS affected male patients.
Assuntos
Hipoxantina Fosforribosiltransferase/genética , Síndrome de Lesch-Nyhan/enzimologia , Síndrome de Lesch-Nyhan/genética , Mutação , Sequência de Bases , Humanos , Masculino , Análise de Sequência de DNARESUMO
Inherited mutations of hypoxanthine guanine phosphoribosyltransferase (HPRT) give rise to Lesch-Nyhan syndrome (LNS) or variants (LNV). We report molecular insights from real-time RT-PCR for HPRT mRNA quantification into the mechanism by which a single mutation located in exon 7 of the HPRT gene: c.500G>T, p.R167M, led to different clinical phenotypes from three male LNV-affected patients in the same family manifesting parallel differences in enzymatic activities. This approach can be applied for understanding genotype-phenotype correlations for other human genetic diseases.