Novel OCTN2 mutations: No genotype–phenotype correlations: Early carnitine therapy prevents cardiomyopathy

Primary systemic carnitine deficiency or carnitine uptake defect (OMIM 212140) is a potentially lethal, autosomal recessive disorder characterized by progressive infantile‐onset cardiomyopathy, weakness, and recurrent hypoglycemic hypoketotic encephalopathy, which is highly responsive to L ‐carnitine therapy. Molecular analysis of the SLC22A5 (OCTN2) gene, encoding the high‐affinity carnitine transporter, was done in 11 affected individuals by direct nucleotide sequencing of polymerase chain reaction products from all 10 exons. Carnitine uptake (at Km of 5 μM) in cultured skin fibroblasts ranged from 1% to 20% of normal controls. Eleven mutations (delF23, N32S, and one 11‐bp duplication in exon 1; R169W in exon 3; a donor splice mutation [IVS3+1 G > A] in intron 3; frameshift mutations in exons 5 and 6; Y401X in exon 7; T440M, T468R and S470F in exon 8) are described. There was no correlation between residual uptake and severity of clinical presentation, suggesting that the wide phenotypic variability is likely related to exogenous stressors exacerbating carnitine deficiency. Most importantly, strict compliance with carnitine from birth appears to prevent the phenotype. © 2002 Wiley‐Liss, Inc.     

N-acetylaspartic aciduria. Clinical, biological and physiopathological study

Two cases of N-acetylaspartic aciduria in siblings are described and compared to the 18 cases already reported. The disease should be considered in childhood when a syndrome of severe encephalopathy with macrocephaly, blindness caused by optic atrophy and diffuse leucodystrophy on CT scan occurs. Urinary organic acids gas chromatography confirms the diagnosis. It is probably inherited as an autosomal recessive trait. Aspartoacylase activity deficiency has been reported and this assay could possibly be used for prenatal diagnosis. Pathogenesis is not clearly understood but N-acetylaspartic acid (NAA) seems to be essential for central nervous system myelination. Clinical and anatomic features of N-acetylaspartic aciduria are very similar to Van Bogaert-Bertrand disease (cerebral spongy degeneration or Canavan disease) but heterogeneity of this disease cannot excluded.     

Biotidinase deficiency: a disease with neurologic and cutaneous expression susceptible to biotin

The authors report 2 familial cases of biotin deficiency. The first neurological signs appeared at the age of 2 years in a boy. The diagnosis was established in his sister in the neonatal period. A review of 41 published cases summarizes the neurologic signs (seizures, ataxia, hypotonia and later, developmental delay and deafness) and the cutaneous signs (rash, alopecia). An early treatment with biotin cures or prevents the clinical signs of the disease in most cases.     

Medium chain acyl-CoA dehydrogenase deficiency. Apropos of a case with demonstration of this enzyme deficiency

The medium chain acyl-CoA deshydrogenase defect: a new inherited metabolic disorder. This enzymatic defect blocks the catabolism of non esterified fatty acids during fasting. Thus, this disease is revealed by a coma due to hypoglycemia in a young child; the presence of dicarboxylic aciduria in such a situation is the main evidence for this diagnosis. Finally, the enzymatic studies performed on skin fibroblasts show a defect in medium chain acyl-CoA deshydrogenase. When a child is investigated away from a coma episode, the ketotic diet induces dicarboxylic aciduria but must be performed in an intensive care unit for its dangers.     

B-6 vitamers and 4-pyridoxic acid in the plasma, erythrocytes, and urine of postmenopausal women

BACKGROUND: Although many studies have reported reduced vitamin B-6 status with aging, little information is available about the specific effects of menopause. OBJECTIVE: We aimed to examine vitamin B-6 metabolism in premenopausal and early postmenopausal women. DESIGN: We examined dietary intake and vitamin B-6 metabolites in the plasma, erythrocytes, and urine of 30 premenopausal women (x +/- SD age: 41.9 +/- 4.8 y) and 30 women (aged 54.0 +/- 3.8 y) who were 4.0 +/- 1.4 y past menopause. RESULTS: Vitamin B-6 intake in the postmenopausal group (1.97 +/- 0.40 mg/d) was significantly greater than that in the premenopausal group (1.63 +/- 0.50 mg/d). Plasma pyridoxal phosphate (PLP) and pyridoxal concentrations and erythrocyte PLP, pyridoxal, and pyridoxamine phosphate concentrations were in the normal range in both groups and did not differ significantly between the 2 groups. Plasma and erythrocyte 4-pyridoxic acid (4-PA) concentrations were significantly higher in the postmenopausal group than in the premenopausal group, which may have been due at least partly to the slightly higher vitamin B-6 intake of the former group. Erythrocyte 4-PA was correlated (r = -0.37, P < 0.01) with serum estradiol in both groups. Urinary 4-PA did not differ significantly between the 2 groups. The serum phosphate concentration was higher in the postmenopausal group than in the premenopausal group, and it was correlated (r = 0.40, P < 0.01) with plasma PLP. Inhibition of alkaline phosphatase by the increased phosphate may help to increase plasma PLP. CONCLUSION: Menopause may not necessarily be associated with a decrease in vitamin B-6 status.