References of "Mitchell, Grant A"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailLow citrulline in Leigh disease: still a biomarker of maternally inherited Leigh syndrome.
Debray, François-Guillaume ULg; Lambert, Marie-Hélène ULg; Allard, Pierre et al

in Journal of Child Neurology (2010), 25(8), 1000-2

Two siblings presented with encephalopathy, lactic acidosis, and hypocitrullinemia. Muscle and liver biopsies were considered for respiratory chain studies, but because of hypocitrullinemia, molecular ... [more ▼]

Two siblings presented with encephalopathy, lactic acidosis, and hypocitrullinemia. Muscle and liver biopsies were considered for respiratory chain studies, but because of hypocitrullinemia, molecular analysis for maternally inherited Leigh syndrome was first performed, revealing in both siblings the mitochondrial DNA T8993G mutation (95% heteroplasmy), allowing to avoid tissue biopsies. Hypocitrullinemia, an occasional finding in mitochondrial diseases, has been specifically associated with T8993G mutation. However, only few patients have been reported, and the prevalence of hypocitrullinemia in 8993 mitochondrial DNA mutations is unknown. In a small series of 16 Leigh syndrome patients, sensitivity and specificity of hypocitrullinemia (< or = 12 micromol/L) for 8993 mitochondrial DNA mutations were 66% and 85%, respectively. Although studies in larger cohorts are necessary, we suggest considering T8993G mutation early in the diagnostic evaluation of infantile mitochondrial diseases with hypocitrullinemia, which minimizes the need for invasive procedures associated with a small but nonnegligible risk of complications and incorrect diagnosis. [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
Peer Reviewed
See detailLong-term outcome and clinical spectrum of 73 pediatric patients with mitochondrial diseases.
DEBRAY, François-Guillaume ULg; Lambert, Marie; Chevalier, Isabelle et al

in Pediatrics (2007), 119(4), 722-733

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 ... [more ▼]

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. [less ▲]

Detailed reference viewed: 11 (2 ULg)
Full Text
Peer Reviewed
See detailDiagnostic accuracy of blood lactate-to-pyruvate molar ratio in the differential diagnosis of congenital lactic acidosis.
DEBRAY, François-Guillaume ULg; Mitchell, Grant A; Allard, Pierre et al

in Clinical Chemistry (2007), 53(5), 916-21

BACKGROUND: Although the blood lactate-to-pyruvate (L:P) molar ratio is used to distinguish between pyruvate dehydrogenase deficiency (PDH-D) and other causes of congenital lactic acidosis (CLA), its ... [more ▼]

BACKGROUND: Although the blood lactate-to-pyruvate (L:P) molar ratio is used to distinguish between pyruvate dehydrogenase deficiency (PDH-D) and other causes of congenital lactic acidosis (CLA), its diagnostic accuracy for differentiating between these 2 types of CLA has not been evaluated formally. METHODS: We conducted a retrospective study of all patients followed for mitochondrial diseases between 1985 and 2005 in a tertiary care pediatric hospital. RESULTS: At the recommended cut point of approximately 25, individual median L:P ratio demonstrated low sensitivity and specificity (77% and 91%, respectively) for differentiating between patients with enzymatically proven PDH-D (n = 11) and those with mitochondrial disease but normal pyruvate dehydrogenase (PDH) activity (non-PDH; n = 35). We observed a strong positive association between L:P ratio and blood lactate in non-PDH CLA, whereas this association was weak in PDH-D CLA. Consequently, patient classification based on median L:P ratio showed improved diagnostic accuracy at higher lactate concentrations: for lactate <2.5 mmol/L the area under the ROC curve was not statistically different from 0.5 (P = 0.3), whereas it was statistically different for lactate >2.5 mmol/L. In the 2.5 to 5.0 mmol/L lactate category, the sensitivity and specificity at an optimal cut point of 18.4 were 93% (95% CI, 77%-99%) and 71% (95% CI, 20%-96%), respectively; for lactate >5.0 mmol/L, with an optimal cut point of 25.8, sensitivity and specificity were 96% (95% CI, 77%-99%) and 100% (95% CI, 59%-100%), respectively. CONCLUSION: Usefulness of the L:P ratio for differentiating non-PDH and PDH-D types of CLA increases at higher lactate concentrations. [less ▲]

Detailed reference viewed: 25 (0 ULg)
Full Text
Peer Reviewed
See detailLong-term outcome of Leigh syndrome caused by the NARP-T8993C mtDNA mutation.
DEBRAY, François-Guillaume ULg; Lambert, Marie; Lortie, Anne et al

in American Journal of Medical Genetics. Part A (2007), 143A(17), 2046-51

Mutations at mitochondrial DNA (mtDNA) nucleotide 8993 can cause neurogenic weakness, ataxia and retinitis pigmentosa (NARP syndrome), or maternally inherited Leigh syndrome (LS), with a correlation ... [more ▼]

Mutations at mitochondrial DNA (mtDNA) nucleotide 8993 can cause neurogenic weakness, ataxia and retinitis pigmentosa (NARP syndrome), or maternally inherited Leigh syndrome (LS), with a correlation between the amount of mutant mtDNA and the severity of the neurological disease. The T8993C mutation is generally considered to be clinically milder than the T8993G mutation but when the level of heteroplasmy exceeds 90%, progressive neurodegeneration has been found. We report on a long-term follow-up of a patient who presented at 4 years of age with typical LS but showed an unexpected resolution of his symptoms and a favorable outcome. At 18 years of age, his neurological examination was near normal, with neither peripheral neuropathy nor retinopathy. mtDNA analysis identified the presence of T8993C mutation at high level (>95%) in the patient's blood leukocytes. This case report and literature review emphasizes the variability of the phenotypic expression of the T8993C mutation and the need for caution in predictive counseling in such patients. (c) 2007 Wiley-Liss, Inc. [less ▲]

Detailed reference viewed: 15 (1 ULg)
Full Text
Peer Reviewed
See detailIntermittent peripheral weakness as the presenting feature of pyruvate dehydrogenase deficiency.
DEBRAY, François-Guillaume ULg; Lambert, Marie; Vanasse, Michel et al

in European journal of pediatrics (2006), 165(7), 462-466

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 ... [more ▼]

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 E1alpha subunit (PDHA1). Taken in context with the literature, these patients suggest that acute weakness initially resembling Guillain-Barre syndrome is a potentially reversible and probably underdiagnosed manifestation of PDH deficiency and that peripheral nerve function should be evaluated in PDH-deficient patients. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
Peer Reviewed
See detailRecurrent pancreatitis in mitochondrial cytopathy.
DEBRAY, François-Guillaume ULg; Drouin, Eric; Herzog, Denise et al

in American Journal of Medical Genetics. Part A (2006), 140(21), 2330-5

Diabetes mellitus and exocrine insufficiency are the commonest pancreatic manifestations of mitochondrial diseases. In contrast, pancreatitis has rarely been described in mitochondrial syndromes. We ... [more ▼]

Diabetes mellitus and exocrine insufficiency are the commonest pancreatic manifestations of mitochondrial diseases. In contrast, pancreatitis has rarely been described in mitochondrial syndromes. We report on a patient with Kearns-Sayre syndrome and recurrent episodes of acute pancreatitis for which no explanation could be found other than the associated mitochondrial dysfunction. Interestingly, pharmacological disruption of mitochondrial metabolism in various models as well as in patients can cause pancreatitis, further supporting this association. A diagnosis of pancreatitis should be considered in any patients with mitochondrial disease and recurrent abdominal pain. [less ▲]

Detailed reference viewed: 13 (0 ULg)