DGUOK相关线粒体DNA耗竭综合征1例报道及文献复习

A boy, aged 4 months, had the major clinical manifestations of prolonged jaundice and hepatomegaly. Multiple biochemical tests revealed abnormal liver function along with elevated alpha-fetoprotein and lactate. Genetic analysis confirmed that the boy had the mutations of c.589C>T(p.Gln197Ter) and c.687G>C(p.Trp229Cys) in the DGUOK gene, both of which were novel mutations and were determined to be pathogenic and likely pathogenic respectively, by a variety of bioinformatics tools and the ACMG standard. Therefore, the boy was confirmed to have DGUOK-related mitochondrial DNA depletion syndrome. Literature review showed that onset of liver disease in infancy was the main clinical feature of this disease, and some children presented with nervous system manifestations. Abnormal laboratory results included abnormal liver function, increases in blood lactate, serum ferritin and alpha-fetoprotein, and hypoglycemia. Such children had marked heterogeneity of DGUOK gene mutations, with missense mutations as the most common type. This disease tended to have a poor prognosis, and 79.6% of the children died before the age of 3 years.

Incidence of Primary Mitochondrial Disease in Children Younger Than 2 Years Presenting With Acute Liver Failure

BACKGROUND

Mitochondrial liver disease (MLD), and in particular mitochondrial DNA (mtDNA) depletion syndrome (MDS) is an important cause of acute liver failure (ALF) in infancy. Early and accurate diagnosis is important because liver transplantation (LT) is often contraindicated. It is unclear which methods are the best to diagnose MLD in the setting of ALF.

OBJECTIVE

The aim of the study was to determine the incidence of MLD in children younger than 2 years with ALF and the utility of routine investigations to detect MLD.

METHODS

Thirty-nine consecutive infants with ALF were admitted to a single unit from 2009 to 2011. All were extensively investigated using an established protocol. Genes implicated in mitochondrial DNA depletion syndrome were sequenced in all cases and tissue mtDNA copy number measured where available.

RESULTS

Five infants (17%) had genetically proven MLD: DGUOK (n = 2), POLG (n = 2), and MPV17 (1). Four of these died, whereas 1 recovered. Two had normal muscle mtDNA copy number and 3 had normal muscle respiratory chain enzymes. An additional 8 children had low hepatic mtDNA copy number but pathogenic mutations were not detected. One of these developed fatal multisystemic disease after LT, whereas 5 who survived remain well without evidence of multisystemic disease up to 6 years later. Magnetic resonance spectroscopy did not distinguish between those with and without MLD.

CONCLUSIONS

Low liver mtDNA copy number may be a secondary phenomenon in ALF.Screening for mtDNA maintenance gene mutations may be the most efficient way to confirm MLD in ALF in the first 2 years of life.

线粒体DNA耗竭综合征1例临床特点和DGUOK基因突变分析

The aim of this study was to investigate the clinical features and DGUOK gene mutations of an infant with mitochondrial DNA depletion syndrome (MDS). The patient (more than 7 months old) manifested as hepatosplenomegaly, abnormal liver function, nystagmus and psychomotor retardation. Genetic DNA was extracted from peripheral blood samples of the patient and her parents. Targeted Exome Sequencing was performed to explore the genetic causes. Sanger sequencing was carried out to confirm the detected mutations. The sequencing results showed that the patient was a compound heterozygote for c.679G>A and c.817delT in the DGUOK gene. The former was a reportedly pathogenic missense mutation of maternal origin, while the latter, a frameshift mutation from the father, has not been described yet. The findings in this study expand the mutation spectrum of DGUOK gene, and provide molecular evidence for the etiologic diagnosis of the patient as well as for the genetic counseling and prenatal diagnosis in the family.

[Clinical features and DGUOK mutations of an infant with mitochondrial DNA depletion syndrome]

The aim of this study was to investigate the clinical features and DGUOK gene mutations of an infant with mitochondrial DNA depletion syndrome (MDS). The patient (more than 7 months old) manifested as hepatosplenomegaly, abnormal liver function, nystagmus and psychomotor retardation. Genetic DNA was extracted from peripheral blood samples of the patient and her parents. Targeted Exome Sequencing was performed to explore the genetic causes. Sanger sequencing was carried out to confirm the detected mutations. The sequencing results showed that the patient was a compound heterozygote for c.679G>A and c.817delT in the DGUOK gene. The former was a reportedly pathogenic missense mutation of maternal origin, while the latter, a frameshift mutation from the father, has not been described yet. The findings in this study expand the mutation spectrum of DGUOK gene, and provide molecular evidence for the etiologic diagnosis of the patient as well as for the genetic counseling and prenatal diagnosis in the family.