Single-strand conformation polymorphism analysis of the FMR1 gene in autistic and mentally retarded children in Japan

Fragile X syndrome is one of the most common causes of mental retardation in males, and patients with fragile X syndrome occasionally develop autism. It is usually caused by an expansion of the trinucleotide repeat in the 5’-untranslated region of the FMR1 gene, but in a small number of patients deletions and point mutations have been identified. We screened all 17 exons of the FMR1 gene for mutations in 90 autistic or mentally retarded children using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. No mutations were found in 76male patients. However, one female patient was heterozygous for a normal allele and a mutant allele with an A to C substitution at nucleotide 879 in exon 9. This mutation was not found in 50 controls. Reverse transcription-PCR revealed that a large proportion of the mutant transcripts were spliced aberrantly, causing premature termination of the protein synthesis. Although uncommon, point mutations in theFMR1 gene maybe a cause of autism and mental retardation in Japanese patients

ピルビンサン ダッスイソ コウソ フクゴウタイ イジョウショウ ジョジ カンジャ ノ イデンシ シンダン システム ノ カクリツ

Pyruvate dehydrogenase (PDH) complex deficiency is one of the important causes of congenital lactic acidemia and mostly due to defect in the α subunit of PDH (E1α), of which gene is located on the X chromosome. The diagnosis of the PDH E1α deficiency is usually established by the measurement of the PDH complex activity in cultured cells. However, some female patients, who are heterozygous for the mutant allele, cannot be diagnosed only by the assay of PDH complex activity, because of the skewed X-chromosome inactivation in cultured cells. Then, we established DNA diagnostic system for PDH E1α deficiency using X inactivation assay, no RI PCR-SSCP, and direct sequencing. With this DNA diagnostic system we could diagnose 4 female patients as PDH E1α deficiency from 14 female patients who were suspected PDH complex deficiency from the clinical features and concentrations of lactate and pyruvate in the blood but showed normal PDH complex activity in their cultured cells. These results indicate that this DNA diagnostic system for PDH E1 αdeficiency is very useful