RESUMO
Mitochondrial DNA (mtDNA) maintenance defects are a group of diseases caused by deficiency of proteins involved in mtDNA synthesis, mitochondrial nucleotide supply, or mitochondrial dynamics. One of the mtDNA maintenance proteins is MPV17, which is a mitochondrial inner membrane protein involved in importing deoxynucleotides into the mitochondria. In 2006, pathogenic variants in MPV17 were first reported to cause infantile-onset hepatocerebral mtDNA depletion syndrome and Navajo neurohepatopathy. To date, 75 individuals with MPV17-related mtDNA maintenance defect have been reported with 39 different MPV17 pathogenic variants. In this report, we present an additional 25 affected individuals with nine novel MPV17 pathogenic variants. We summarize the clinical features of all 100 affected individuals and review the total 48 MPV17 pathogenic variants. The vast majority of affected individuals presented with an early-onset encephalohepatopathic disease characterized by hepatic and neurological manifestations, failure to thrive, lactic acidemia, and mtDNA depletion detected mainly in liver tissue. Rarely, MPV17 deficiency can cause a late-onset neuromyopathic disease characterized by myopathy and peripheral neuropathy with no or minimal liver involvement. Approximately half of the MPV17 pathogenic variants are missense. A genotype with biallelic missense variants, in particular homozygous p.R50Q, p.P98L, and p.R41Q, can carry a relatively better prognosis.
Assuntos
DNA Mitocondrial/genética , Transtornos Heredodegenerativos do Sistema Nervoso , Hepatopatias , Proteínas de Membrana/genética , Doenças Mitocondriais , Proteínas Mitocondriais/genética , Doenças do Sistema Nervoso Periférico , Transtornos Heredodegenerativos do Sistema Nervoso/diagnóstico , Transtornos Heredodegenerativos do Sistema Nervoso/genética , Transtornos Heredodegenerativos do Sistema Nervoso/metabolismo , Humanos , Fígado/metabolismo , Hepatopatias/diagnóstico , Hepatopatias/genética , Hepatopatias/metabolismo , Mitocôndrias/genética , Doenças Mitocondriais/diagnóstico , Doenças Mitocondriais/genética , Doenças Mitocondriais/metabolismo , Mutação , Doenças do Sistema Nervoso Periférico/diagnóstico , Doenças do Sistema Nervoso Periférico/genética , Doenças do Sistema Nervoso Periférico/metabolismoRESUMO
We present 4 normal-weight sibling children with lysosomal acid lipase deficiency (LAL-D). LAL-D was considered in the differential diagnosis based on the absence of secondary causes and primary inherited traits for their marked hyperlipidemia, together with unexplained hepatic transaminase elevation. Residual lysosomal acid lipase activity confirmed the diagnosis. DNA sequencing of LIPA indicated that the siblings were compound heterozygotes (c.894G>A and c.428+1G>A). This case describes the unusual occurrence of all offspring from the same nonconsanguineous mother and father inheriting compound heterozygosity of a recessive trait and the identification of an apparently unique LIPA mutation (c.428+1G>A). It highlights the collaborative effort between a lipidologist and gastroenterologist in developing a differential diagnosis leading to the confirmatory diagnosis of this rare, life-threatening disease. With the availability of an effective enzyme replacement therapy (sebelipase alfa), LAL-D should be entertained in the differential diagnosis of children, adolescents, and young adults with idiopathic hyperlipidemia and unexplained hepatic transaminase elevation.