A novel activation-induced cytidine deaminase gene mutation in a Tunisian family with hyper IgM syndrome.
Mutations in activation-induced cytidine deaminase can cause an autosomal recessive form of hyper-IgM syndrome. We have examined a Tunisian family composed of six members: two healthy parents, their two healthy daughters and two affected sons. We found a homozygous transversion G to T in the two sons while heterozygosity for the mutation was found in all other family members. This alteration is localised in intron 2 at the +1 position resulting in defective splicing. Use of various intronic cryptic splice-sites led to expression of various aberrant mRNA species.


CONCLUSIONS
This is a novel mutation found in the gene encoding for activation-induced cytidine deaminase in a Tunisian family with hyper-IgM type 2 syndrome. This alteration leads to the use of two cryptic splicing sites causing the formation of two different mRNA species.
Fiorini
Claudia
C
Istituto di Medicina Molecolare A. Nocivelli, Clinica Pediatrica, Università di Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy.
Jilani
Sawssen
S
Losi
Claretta Gioia
CG
Silini
Antonietta
A
Giliani
Silvia
S
Ferrari
Simona
S
Notarangelo
Luigi D
LD
Plebani
Alessandro
A
Sfar
Taher
T
Helal
Ahmed
A
D000328:Adult; D002648:Child; D003564:Cytidine Deaminase / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D006942:Hypergammaglobulinemia / Q000201:enzymology* / Q000235:genetics*; D007075:Immunoglobulin M / Q000097:blood / Q000235:genetics*; D007438:Introns; D008297:Male; D009154:Mutation; D012326:RNA Splicing; D035781:Siblings
D007075:Immunoglobulin M; D003564:Cytidine Deaminase