Jean-Claude Décarie

Long-term Outcome and Clinical Spectrum of 73 Pediatric Patients With Mitochondrial Diseases

OBJECTIVES. We sought to determine the clinical spectrum, survival, and long-term functional outcome of a cohort of pediatric patients with mitochondrial diseases and to identify prognostic factors. METHODS. Medical charts were reviewed for 73 children diagnosed between 1985 and 2005. The functional status of living patients was assessed prospectively by using the standardized Functional Independence Measure scales. RESULTS. Patients fell into 7 phenotypic categories: neonatal-onset lactic acidosis (10%), Leigh syndrome (18%), nonspecific encephalopathy (32%), mitochondrial (encephalo)myopathy (19%), intermittent neurologic (5%), visceral (11%), and Leber hereditary optic neuropathy (5%). Age at first symptoms ranged from prenatal to 16 years (median: 7 months). Neurologic symptoms were the most common (90%). Visceral involvement was observed in 29% of the patients. A biochemical or molecular diagnosis was identified for 81% of the patients as follows: deficiency of complex IV (27%), of pyruvate dehydrogenase or complex I (25% each), of multiple complexes (13%), and of pyruvate carboxylase (5%) or complexes II+III (5%). A mitochondrial DNA mutation was found in 20% of patients. At present, 46% of patients have died (median age: 13 months), 80% of whom were <3 years of age. Multivariate analysis showed that age at first symptoms was a major independent predictor of mortality: patients with first symptoms before 6 months had a highly increased risk of mortality. Cardiac or visceral involvement and neurologic crises were not independent prognostic factors. Living patients showed a wide range of independence levels that correlated positively with age at first symptoms. Among patients aged >5 years (n = 32), 62% had Functional Independence Measure quotients of >0.75. CONCLUSIONS. Mitochondrial diseases in children span a wide range of symptoms and severities. Age at first symptoms is the strongest predictor mortality. Despite a high mortality rate in the cohort, 62% of patients aged >5 years have only mild impairment or normal functional outcome.

Del(14)(q22.1q23.2) in a patient with anophthalmia and pituitary hypoplasia

Only few cases with an interstitial deletion of chromosome 14 have been described so far. We report on a 21-month-old girl with an interstitial deletion of the long arm of chromosome 14, del(14)(q22.1q23.2). She presented with bilateral anophthalmia, absent left external auditory canal, facial asymmetry, microretrognathia, hypotonia, and psychomotor retardation. Skeletal X-rays showed lambdoid craniosynostosis, a very small sella turcica and cervical vertebral anomalies. Brain MRI showed the absence of the optic chiasm, an hypoplastic pituitary gland, and cortical atrophy. No cardiac or abdominal malformations were found. Two other patients with a similar deletion, (del(14)(q22.1q23) and del(14)(q22.1q22.3)), are described. Both presented with bilateral anophthalmia and absent pituitary or hypogonadism. These three cases suggest that the region 14q22 is important for eye and pituitary development. Interestingly, the human BMP-4 gene, a member of the TGF-beta superfamily, maps to 14q22-q23 and may play a role in pituitary and eye development.

Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy

We analyzed four families that presented with a similar condition characterized by congenital microcephaly, intellectual disability, progressive cerebral atrophy, and intractable seizures. We show that recessive mutations in the ASNS gene are responsible for this syndrome. Two of the identified missense mutations dramatically reduce ASNS protein abundance, suggesting that the mutations cause loss of function. Hypomorphic Asns mutant mice have structural brain abnormalities, including enlarged ventricles and reduced cortical thickness, and show deficits in learning and memory mimicking aspects of the patient phenotype. ASNS encodes asparagine synthetase, which catalyzes the synthesis of asparagine from glutamine and aspartate. The neurological impairment resulting from ASNS deficiency may be explained by asparagine depletion in the brain or by accumulation of aspartate/glutamate leading to enhanced excitability and neuronal damage. Our study thus indicates that asparagine synthesis is essential for the development and function of the brain but not for that of other organs.

LRPPRC mutations cause a phenotypically distinct form of Leigh syndrome with cytochrome c oxidase deficiency

Background The natural history of all known patients with French-Canadian Leigh disease (Saguenay-Lac-St-Jean cytochrome c oxidase deficiency, MIM220111, SLSJ-COX), the largest known cohort of patients with a genetically homogeneous, nuclear encoded congenital lactic acidosis, was studied. Results 55 of 56 patients were homozygous for the A354V mutation in LRPPRC. One was a genetic compound (A354V/C1277Xdel8). Clinical features included developmental delay, failure to thrive, characteristic facial appearance and, in 90% of patients, acute crises that have not previously been detailed, either metabolic (fulminant lactic acidosis) and/or neurological (Leigh syndrome and/or stroke-like episodes). Survival ranged from 5 days to >30 years. 46/56 patients (82%) died, at a median age of 1.6 years. Of 73 crises, 38 (52%) were fatal. The immediate causes of death were multiple organ failure and/or Leigh disease. Major predictors of mortality during crises (p<0.005) were hyperglycaemia, hepatic cytolysis, and altered consciousness at admission. Compared to a group of SURF1-deficient Leigh syndrome patients assembled from the literature, SLSJ-COX is distinct by the occurrence of metabolic crises, leading to earlier and higher mortality (p=0.001). Conclusion SLSJ-COX is clinically distinct, with acute fatal acidotic crises on a backdrop of chronic moderate developmental delay and hyperlactataemia. Leigh syndrome is common. Stroke-like episodes can occur. The Leigh syndrome of SLSJ-COX differs from that of SURF1-related COX deficiency. SLSJ-COX has a different spectrum of associated abnormalities, acidotic crises being particularly suggestive of LRPPRC related Leigh syndrome. Even among A354V homozygotes, pronounced differences in survival and severity occur, showing that other genetic and/or environmental factors can influence outcome.

The clinical spectrum of nodular heterotopias in children: Report of 31 patients

Purpose:  The phenotypic and etiologic spectrum in adults with nodular heterotopias (NHs) has been well characterized. However, there are no large pediatric case series. We, therefore, wanted to review the clinical features of NHs in our population.

Effectiveness of pamidronate as treatment of symptomatic osteonecrosis occurring in children treated for acute lymphoblastic leukemia.

Osteonecrosis (ON) is a severe complication of acute lymphoblastic leukemia (ALL) treatments. Recent studies suggest that bisphosphonates might reduce pain and loss of motor function in patients with ON. We assessed the effects of pamidronate compared to standard care in patients with symptomatic ON (sON) and studied whether steroids might be continued after diagnosis of ON in some patients.

Intermittent peripheral weakness as the presenting feature of pyruvate dehydrogenase deficiency.

Two unrelated children presenting with episodic isolated peripheral weakness were found to have pyruvate dehydrogenase (PDH) deficiency (OMIM 312170) due to previously undescribed mutations (Pro250Thr, Arg88Cys) in the gene for the E1α subunit (PDHA1). Taken in context with the literature, these patients suggest that acute weakness initially resembling Guillain-Barré syndrome is a potentially reversible and probably underdiagnosed manifestation of PDH deficiency and that peripheral nerve function should be evaluated in PDH-deficient patients.

Acute Combined Central and Peripheral Nervous System Demyelination in Children

Reports of acute combined central and peripheral nervous system acquired inflammatory demyelination are rare in children. This study aimed to (1) define the clinical features and prognoses of patients with this entity; and (2) compare these patients with children presenting isolated acute central or peripheral nervous system demyelination. A retrospective chart review of 523 children with central or peripheral nervous system demyelination hospitalized between 1993-2006 was undertaken. Among these, 93 fulfilled criteria (clinical features and positive magnetic resonance imaging or electromyography/nerve conduction studies) for either acute central (n = 37; 39.8%) or peripheral (n = 43; 46%) nervous system demyelination, or a combination of the two (n = 13; 14%). Significant differences between groups were evident for age (median, 10 versus 7 versus 11 years, respectively; P = 0.047), admission to pediatric intensive care unit (8% versus 30% versus 58%, respectively; P = 0.001), length of hospital stay (median, 8 versus 9 versus 29 days, respectively; P < 0.001), treatment with steroids (52% versus 7% versus 75%, respectively; P < 0.001) and immunoglobulins (11% versus 81% versus 75%, respectively; P < 0.001), and poor evolution (3% versus 12% versus 54%, respectively; P = 0.002). This entity in children is not rare, and has a poorer outcome than isolated central or peripheral nervous system demyelination. Assessment is needed for a better understanding of risk factors, etiologies, management, and prognosis.

Long-term Visual Outcome of Methylmalonic Aciduria and Homocystinuria, Cobalamin C Type

OBJECTIVE To describe the long-term ophthalmologic outcomes of patients with methylmalonic aciduria and homocystinuria, cobalamin C type (cblC). DESIGN Retrospective case series. PARTICIPANTS All patients with cblC referred to the Department of Ophthalmology of the Centre Hospitalier Universitaire Sainte-Justine from 1984 through 2012 were studied. Twelve such patients were identified. METHODS Clinical ophthalmic examinations, neuroimaging, electroretinography, and the results of MMACHC mutation analysis were reviewed retrospectively. MAIN OUTCOME MEASURES We examined visual acuity, ocular alignment, presence of maculopathy and peripheral retinopathy, optic atrophy, and nystagmus. Photopic and scotopic electroretinograms were reviewed. We examined and compared mutations in the MMACHC gene. Neuroimaging abnormalities were compiled when available. RESULTS Twelve cblC patients were followed up from 2 to 23 years (average, 10 years). Eleven of 12 patients were diagnosed before the age of 1 year (range, birth-2 years). An initial ophthalmic examination was performed within the first year of age in 9 of 12 patients. Visual acuity at the time of presentation was variable, ranging from light perception to 20/20. Visual acuity was worse than 20/100 in 75% (9/12) of patients at last follow-up. Eight patients (67%) had obvious maculopathy on fundus examination. Other findings included peripheral retinopathy (8/12 [67%]), nystagmus (8/12 [67%]), strabismus (5/12 [42%]), and optic atrophy (6/12 [50%]). Funduscopic deterioration was documented in 1 patient, whereas electrophysiologic changes occurred in 4 patients. Neuroimaging results were available in 7 of the patients, revealing corpus callosum atrophy (7/7 [100%]) and periventricular white matter loss (6/7 [85%]). CONCLUSIONS Most children in our series had early-onset disease with neurologic manifestations and abnormal ophthalmologic examination results. Despite early treatment, many early-onset cblC patients have poor visual function.

A treatable new cause of chorea: Beta-ketothiolase deficiency

Department of Medical Genetics, Montreal Children’s Hospital, Montr eal, Queb ec, Canada Department of Neurology and Neurosurgery, Montreal Children’s Hospital, Montr eal, Qu ebec, Canada McGill University Health Centre, Montreal Children’s Hospital, Montr eal, Qu ebec, Canada Department of Pediatrics, Gifu University Graduate School of Medicine, Gifu, Japan Department of Medical Imaging, CHUM, Universit e de Montr eal, Montr eal, Qu ebec, Canada CHU Sainte-Justine, Universit e de Montr eal, Montr eal, Qu ebec, Canada Andr e Barbeau Movement Disorders Unit, CHUM, Universit e de Montr eal, Montr eal, Qu ebec, Canada Division of Medical Genetics, Department of Pediatrics, Universit e de Montr eal, Montr eal, Qu ebec, Canada