Adenosine deaminase deficiency due to heterozygous abnormality consisting of a deletion of exon 7 and the absence of enzyme mRNA

✍ Scribed by Saburo Kashii; Kazuhiko Ito; Sumie Monden; Yoshiki Sasai; Kunihiro Tsuchida; Masahiro Fujita; Hiroshi Kawamoto; Mihoko Norioka; Minoru Okuma

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 440 KB
• Volume: 47
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240470107

✦ Synopsis

An adenosine deaminase (ADA;EC 3.5.4.4)-deficient B lymphoblastoid cell line BAD05 derived from a Japanese patient with severe combined immunodeficiency disease and two B lymphoblastoid cell lines, BAM05 from his mother and BAFO5 from his father, were characterized. To identify mutations affecting ADA activity, we prepared cDNAs to ADA mRNAs of the BAD05 cell line for nucleotide sequencing. Sequence analysis of one of the BAD05 ADA cDNA clones revealed deletion of exon 7, and one point mutation of base 629 from G to A that did not affect the amino acid sequence. All clones of the BAD05 cell line so far examined showed the absence of exon 7 by Southern blotting analysis. Ribonuclease protection assay with an RNA probe spanning from exon 5 to exon 11 showed that the BAD05 ADA mRNA had a deletion of exon 7, the BAM05 mRNA had normal length, and the BAF05 mRNA had two species with a deletion of exon 7 and with normal length. Consequently, the patient's ADA genes resulted from one allele of the 6AM05 ADA gene that did not produce a detectable mRNA, and the other allele of the BAF05 ADA gene producing an aberrant mRNA without exon 7.