The de novo chromosome 16 translocations of two patients with abnormal phenotypes (mental retardation and epilepsy) disrupt the A2BP1 gene.
The 16p13.3 breakpoints of two de novo translocations of chromosome 16, t(1;16) and t(14;16), were shown by initial mapping studies to have physically adjacent breakpoints. The translocations were ascertained in patients with abnormal phenotypes characterized by predominant epilepsy in one patient and mental retardation in the other. Distamycin/DAPI banding showed that the chromosome 1 breakpoint of the t(1;16) was in the pericentric heterochromatin therefore restricting potential gene disruption to the 16p13.3 breakpoint. The breakpoints of the two translocations were localized to a region of 3.5 and 115 kb respectively and were approximately 900 kb apart. The mapping was confirmed by fluorescence in situ hybridization (FISH) of clones that spanned the breakpoints to metaphase spreads derived from the patients. The mapping data showed both translocations disrupted the ataxin-2-binding protein 1 ( A2BP1) gene that encompasses a large genomic region of 1.7 Mb. A2BP1 encodes a protein that is known to interact with the spinocerebellar ataxia type 2 ( SCA2) protein. It is proposed that disruption of the A2BP1 gene is a cause of the abnormal phenotype of the two patients. Ninety-six patients with sporadic epilepsy and 96 female patients with mental retardation were screened by SSCP for potential mutations of A2BP1. No mutations were found, suggesting that disruption of the A2BP1 gene is not a common cause of sporadic epilepsy or mental retardation.
Bhalla
Kavita
K
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Phillips
Hilary A
HA
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Crawford
Joanna
J
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
McKenzie
Olivia L D
OLD
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Mulley
John C
JC
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Eyre
Helen
H
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Gardner
Alison E
AE
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Kremmidiotis
Gabriel
G
Department of Genetic Medicine, Women's and Children's Hospital, North Adelaide, South Australia, Australia.
Callen
David F
DF
Department of Medicine, Breast Cancer Genetics Group, Hanson Institute (North Building), Institute of Medical and Veterinary Science, University of Adelaide, P.O. Box 14, Rundle Mall, Adelaide, South Australia, 5000, Australia. david.callen@imvs.sa.gov.au.
D000293:Adolescent; D000067528:Ataxins; D002675:Child, Preschool; D002874:Chromosome Mapping; D002885:Chromosomes, Human, Pair 16; D004827:Epilepsy / Q000235:genetics*; D005091:Exons; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008607:Intellectual Disability / Q000235:genetics*; D007438:Introns; D008297:Male; D008957:Models, Genetic; D009154:Mutation; D009419:Nerve Tissue Proteins; D010641:Phenotype; D020161:Physical Chromosome Mapping; D018807:Polymorphism, Single-Stranded Conformational; D011506:Proteins / Q000235:genetics; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000235:genetics*; D014178:Translocation, Genetic
D000067528:Ataxins; D009419:Nerve Tissue Proteins; D011506:Proteins; C455479:RBFOX1 protein, human; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins