Clinical onset and course, response to treatment and outcome in 24 patients with the cblE or cblG remethylation defect complemented by genetic and in vitro enzyme study data.

BACKGROUND: The cobalamin E (cblE) (MTRR, methionine synthase reductase) and cobalamin G (cblG) (MTR, methionine synthase) defects are rare inborn errors of cobalamin metabolism leading to impairment of the remethylation of homocysteine to methionine. METHODS: Information on clinical and laboratory data at initial full assessment and during the course of the disease, treatment, outcome and quality of life was obtained in a survey-based, retrospective study from physicians caring for patients with the CblE or CblG defect. In addition, data on enzyme studies in cultured skin fibroblasts and mutations in the MTRR and MTR gene were analysed. RESULTS: In 11 cblE and 13 cblG patients, failure to thrive, feeding problems, delayed milestones, muscular hypotonia, cognitive impairment and macrocytic anaemia were the most frequent symptoms. Delay in diagnosis depended on age at first symptom and clinical pattern at presentation and correlated significantly with impaired communication abilities at follow-up. Eighteen/22 patients presented with brain atrophy or white matter disease. Biochemical response to treatment with variable combinations of betaine, cobalamin, folate was significant. The overall course was considered improving (n = 8) or stable (n = 15) in 96% of patients, however the average number of CNS symptoms per patient increased significantly over time and 16 of 23 patients were classified as developmentally delayed or severely handicapped. In vitro enzyme analysis data showed no correlation with outcome. Predominantly private mutations were detected and no genotype- phenotype correlations evident. CONCLUSIONS: The majority of patients with the cblE and cblG defect show limited clinical response to treatment and have neurocognitive impairment.

Mutational spectrum of congenital adrenal hyperplasia in Slovenian patients: a novel Ala15Thr mutation and Pro30Leu within a larger gene conversion associated with a severe form of the disease.

OBJECTIVE: To analyse the mutational spectrum, the associated haplotypes and the genotype-phenotype correlation, and to design a reliable and rational approach for CYP21 mutation detection in Slovenian congenital adrenal hyperplasia (CAH) patients. DESIGN: Molecular analysis of the CYP21 gene was performed in 36 CAH patients and 79 family members. METHODS: Southern blotting, sequence-specific PCR amplification (PCR-SSP), sequence-specific oligonucleotide hybridisation (PCR-SSO) and sequencing were used to detect CYP21 gene deletions, conversions and point mutations. RESULTS: CYP21 gene deletion was the most frequent mutation (36.4%). Large gene conversions detectable only by Southern blotting represented 12.1%, and gene conversions involving the promoter region represented 7.6% of the mutated alleles. The most frequent point mutations were: intron 2 splice mutation 16.7%, Ile172Asn mutation 7.6%, Gln318Stop 7.5% and Pro30Leu 12.2% of alleles. A correlation between the genotype and the clinical phenotype similar to those described for large populations was observed. The finding of Pro30Leu mutation linked to a gene conversion could explain the simple virilising (SV) phenotype in compound heterozygotes for the Pro30Leu and a severe mutation. In two siblings with a salt wasting form of CAH (SW-CAH), a novel mutation Ala15Thr was found on the allele characterised by Pro30Leu mutation and gene conversion involving the promoter region. CONCLUSIONS: Our genotyping approach allowed reliable diagnosis of CAH in the Slovenian population. The high frequency of CYP21 gene aberrations on Pro30Leu positive alleles justified systematic searching for a gene conversion in the promoter region using the PCR-SSP reaction.