[Cytochrome c oxydase-deficient Leigh syndrome with homozygous mutation in SURF1 gene]

Leigh syndrome is a heterogeneous disorder, usually due to a defect in oxidative metabolism. Mutations in SURF1 gene have been identified in patients with cytochrome c oxidase deficiency. We report a homozygous splice site deletion [516-2_516-1delAG] in a young girl presenting with cytochrome c oxidase-deficient Leigh syndrome. Identification of molecular defect is indispensable for genetic counselling and prenatal diagnosis.

Clinical features and neuroradiological findings of mitochondrial pathology in six neonates

OBJECTS

We hoped to itemize the clinical and neuroradiological features of six neonates with mitochondrial disorders.

METHODS

We examined a case series of six neonates. The diagnosis of mitochondrial cytopathy was made on the basis of spectrophotometric measurements of respiratory chain enzyme activities in skeletal muscle biopsy specimens. Magnetic resonance (MR) imaging was performed in all cases.

CONCLUSIONS

The antenatal onset in five cases and the lack of any symptom-free interval are suggestive of fetal expression of the disease. No specific symptoms were found: arthrogryposis congenita multiplex in one, progressive hepatocellular dysfunction in three, encephalomyelopathy and cardiomyopathy in four. Complex I deficiency was found in three patients, while one patients had a defect of complex IV and the last a combined defect of complexes I and IV. Neuroradiological findings were either cerebral atrophy or white matter abnormalities of the brain stem in all cases but one and gave additional information, because clinical symptoms are not quite specific. The combination of clinical and MRI findings in neonatal cases can rule out hypoxic ischemic encephalopathy, which suggests an additional screening method to look for mitochondrial disorder.

Inappropriate liver transplantation in a child with Alpers-Huttenlocher syndrome misdiagnosed as valproate-induced acute liver failure

A 3-yr-old boy received valproic acid (VPA) for recurrent seizures. He developed coma and acute liver failure that were attributed to VPA toxicity, and underwent emergency orthotopic liver transplantation (OLTx). Despite good graft function, his neurological state worsened and led to death a few months later. The diagnosis of Alpers-Huttenlocher Syndrome (AHS) was suspected, subsequently to liver Tx, in view of ongoing neurologic deterioration and magnetic resonance imaging (MRI) findings. The syndrome, recessively inherited, associates brain degeneration with liver failure, and is now considered a mitochondrial disease. Enzyme activity deficiencies of the respiratory chain were identified in muscle mitochondria, as well as morphologic abnormalities of mitochondria in the explanted liver. Guidelines for diagnosis are presented, in order to differentiate the liver failure in AHS from that induced by genuine VPA toxicity. It is recommended to avoid liver Tx in patients with AHS given the fatal neurological course of the disease.

Phenotypic expression of diabetes secondary to a T14709C mutation of mitochondrial DNA. Comparison with MIDD syndrome (A3243G mutation): a case report

OBJECTIVE

To analyze the clinical and biochemical features of a recently described point mutation of mitochondrial DNA associated with diabetes. This mutation, characterized by a T14709C transition of a highly conserved nucleotide in the region coding for the glutamic acid tRNA, is heteroplasmic.

RESEARCH DESIGN AND METHODS

The phenotypic expression in the insulin-requiring diabetic proband from the pedigree was compared to that of diabetic probands from three families with the classic A3243G mtDNA mutation (maternally inherited diabetes and deafness [MIDD] syndrome). The same investigations to evaluate pancreatic neurosensorial and muscle involvement were performed in all four patients.

RESULTS

The natural courses of the diabetes and the hearing defects were not different between the two mutations. The patient with the 14,709 mutation, however, exhibited a milder alteration of pigmentary epithelium of retina and a much more severe muscle involvement, as attested by the clinical expression and the concurrent anomalies of muscle energy production evidenced by 31P magnetic resonance spectroscopy, confirming the profound impairment of oxidative processes.

CONCLUSIONS

This novel mutation has to be added to the other known mtDNA anomalies in order to ascribe some diabetes suspected to arise from mitochondrial defects to this nosological framework.

Stüve-Wiedemann syndrome and defects of the mitochondrial respiratory chain

The Stüve-Wiedemann syndrome (SWS) comprises short stature, congenital bowing of the long bones, respiratory distress, and recurrent episodes of unexplained hyperthermia. The skeletal radiographic changes include short and broad long bones, large metaphyses, internal cortical thickening, and angulation primarily of tibiae and femora, but also of humeri and forearm bones. We report 3 cases of SWS from 2 different unrelated consanguineous gypsy families. All 3 cases fulfilled the clinical and radiological criteria of SWS. Two patients died shortly after birth, whereas the third one was alive at the age of one year. Besides hyperthermic episodes, one patient had hyperaminoaciduria, hepatic failure, and megaloblastic anemia which prompted us to investigate mitochondrial respiratory chain in 2 cases. Abnormal results consisting of decreased activities of complex I and IV were found in both. The simultaneous occurrence of both SWS phenotype and abnormal mitochondrial metabolism in two unrelated cases strongly supports the hypothesis of a pathogenetic relationship between the two events. These cases may also be related to recent reports on the effects of the mitochondrial respiratory chain defects on embryogenesis.