Aplasia of the retinal vessels combined with optic nerve hypoplasia, neonatal epileptic seizures, and lactic acidosis due to mitochondrial complex I deficiency

Agenesis of retinal vessels in a newborn with central nervous system developmental abnormality

A full-term infant with neonatal seizures was diagnosed to have corpus callosum agenesis with congenital agyria. His indirect ophthalmoscopical evaluation revealed bilateral complete absence of retinal vessels with normal optic discs and macula. Bilateral lamellar cataracts developed in the second month of follow-up, and his muscle biopsy was consistent with a mitochondrial disorder. Confirmation by molecular analysis could not be performed since parents did not give their consent for further investigation.

Visual function, ocular motility and ocular characteristics in patients with mitochondrial complex I deficiency

PURPOSE

The aims of the present study were to investigate visual function, ocular motility and ocular characteristics in children and young adults with complex I deficiency.

MATERIAL AND METHODS

In a prospective study with longitudinal follow-up, the visual and ocular outcome in 13 patients with deficiency in complex I [nicotine-amide adenine dinucleotide (NADH) dehydrogenase] in the mitochondrial respiratory chain is presented. The patients were diagnosed during 1995-2007 and assessed during 1997-2009 at a median age of 12.8 years (range 3.1-23.4).

RESULTS

Twelve of 13 patients had visual impairment and/or ocular pathology. Four of 10 patients who co-operated in visual assessment had a best corrected decimal visual acuity of ≤ 0.5 in one or both eyes. Cataract surgery was performed in one patient and another patient showed retinal pigmentations and ptosis. Eleven patients demonstrated ocular motility problems, mainly saccade deficiencies. Five patients had optic atrophy (OA), which was bilateral in four patients. In four siblings, the OA showed a similarity to Leber's Hereditary Optic Neuropathy. These patients also had the 11778 G → A mutation in mitochondrial DNA. Only one patient had normal visual acuity and ocular outcome including refraction and visual fields. Follow-up time was median 3.0 years (range 0-11).

CONCLUSION

Visual impairment, ocular motility problems and OA are common in children and young adults with complex I deficiency and should prompt the paediatric ophthalmologist to consider mitochondrial disorders.

Association of optic nerve hypoplasia with mitochondrial cytopathies

Ocular complications are common in the mitochondrial cytopathies and include optic atrophy and retinal degeneration. We retrospectively reviewed 80 patients with nonsyndromic mitochondrial cytopathies (ie, not Kearns-Sayre syndrome, myoclonus epilepsy associated with ragged red fibers [MERRF], mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes [MELAS], neuropathy ataxia and retinitis pigmentosa, Leigh disease, maternally inherited diabetes and deafness, and myoneurogastrointestinal disorder and encephalopathy) and found 10 cases of optic nerve hypoplasia. Optic nerve hypoplasia occurs in at least 12% of patients with nonsyndromic mitochondrial cytopathies. Although the exact pathogenesis of optic nerve hypoplasia in the context of mitochondrial cytopathy is unknown, we postulate that it is the result of excessive apoptosis during embryonic ganglion cell and/or axonal development from abnormal mitochondrial function and cellular energy metabolism.

Spasms in children with definite and probable mitochondrial disease*

The diagnosis of mitochondrial encephalomyopathies is complex and a system for classification of the diagnosis as definite, probable, and possible has been proposed. The objective of this study was to explore the spectrum of epileptic disorders associated with probable and definite mitochondrial disease in children using this classification system. The patient population with mitochondrial disease and epilepsy was selected from a tertiary care children's hospital. Interictal electroencephalograms and video-EEG recordings were used to characterize seizure types. Ten children fulfilled the criteria for probable or definite mitochondrial disease and had epilepsy. Four had siblings with a similar clinical phenotype. Spasms were the most common seizure type and were the initial seizure type in seven patients and two siblings. Four patients had only partial seizures, with or without generalization, and one patient had seizures that were difficult to classify. Blood lactate concentrations were elevated consistently in patients with partial seizures alone but were occasionally normal in children with spasms. Spasms were the most common presenting seizure type in children with probable and definite mitochondrial disease.

The clinical, neuroradiographic, and endocrinologic profile of patients with bilateral optic nerve hypoplasia

PURPOSE

The purpose of the study was to expand on ophthalmologic and endocrinologic data and report the neuroimaging findings of 35 patients with bilateral optic nerve hypoplasia (BONH).

METHODS

A retrospective chart review of 35 children with BONH was conducted. Data on visual acuity, refractive error, and presence of nystagmus and strabismus were collected. Twenty-six children underwent full-endocrinologic evaluation and magnetic resonance imaging or computed tomography scanning.

RESULTS

The male:female ratio was 2:1. Ten percent of eyes had visual acuity of 20/60 or better, whereas 34% had no light perception. Eighty-six percent of eyes had acuity less than 20/200, and 80% of patients were legally blind. Most patients (86%) had nystagmus or strabismus or both. Forty-six percent had absence of the septum pellucidum and corpus callosum on neuroimaging. Twenty-seven percent of patients had endocrinologic abnormalities, with growth hormone deficiency being the most common. Panhypopituitarism occurred in 11.5% of children.

CONCLUSIONS

Although the visual prognosis of children with BONH generally is poor, 10% of such patients have excellent acuity. In contrast to previous reports, endocrine abnormalities were seen in only one quarter of patients, and the full-blown deMorsier syndrome (septo-optic dysplasia with panhypopituitarism) was seen in only 11.5% of patients with BONH.

Severe complex I deficiency in a case of neonatal-onset lactic acidosis and fatal liver failure

We report a newborn admitted to our service on the 2nd day of life because of hypotonia and metabolic acidosis. A progressive hepatocellular dysfunction dominated the clinical picture and the patient died at 13 months of age because of severe hepatic failure. Persistent lactic acidosis, high ketone bodies levels and high-normal lactate/pyruvate and 3-hydroxybutyrate/acetoacetate molar ratios in plasma were found. Investigation of a liver biopsy revealed low activities of all the mitochondrial respiratory chain enzymes but in particular a marked decrease of complex I (NADH cytochrome c reductase) activity. All respiratory chain enzyme activities were normal in cultured skin fibroblasts. Mitochondrial DNA analysis failed to detect any major rearrangements. Although only a few cases have been reported so far, it is becoming clear that liver should be considered as one of the organs involved in oxidative phosphorylation disorders. The finding of unexplained progressive liver failure with poor neurological conditions, lactic acidaemia and ketonuria strongly warrants investigation for a respiratory chain disorder. Moreover, the finding of normal respiratory enzyme activities in a tissue other than liver does not rule out the existence of an oxidative phosphorylation disorder in patients with hepatocellular disease of unexplained origin.

Mitochondrial myopathy with anemia, cardiomyopathy, and lactic acidosis: a distinct late onset mitochondrial disorder

A 40-year-old woman presented with profound muscle weakness resulting in failure to wean from a ventilator and persistent lactic acidosis after having recovered from a pneumonia complicated by adult respiratory distress syndrome, myocardial infarction, renal failure and shock. She had a 28 year history of chronic anemia and exercise intolerance. Anemia and thrombocytopenia persisted after admission. Nonobstructive hypertrophic cardiomyopathy was present. A stroke-like episode occurred. A mitochondrial myopathy with deficiencies in complexes IV and II was demonstrated, but no DNA defect has yet been found. This patient represents a distinct clinical presentation of a mitochondrial disorder characterized by late onset mitochondrial myopathy, chronic anemia, cardiomyopathy, and lactic acidosis.