Identification of a mutation in synapsin I, a synaptic vesicle protein, in a family with epilepsy
- 1Institute of Human Genetics, International Centre for Life, Newcastle upon Tyne, UK
- 2Northgate Hospital, Morpeth, Northumberland, UK
- 3Radiology Department, Royal Victoria Infirmary, Newcastle upon Tyne
- Correspondence to: Professor Judith A Goodship Institute of Human Genetics, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK;
- Received 22 August 2003
- Accepted 24 October 2003
A four generation family is described in which some men of normal intelligence have epilepsy and others have various combinations of epilepsy, learning difficulties, macrocephaly, and aggressive behaviour. As the phenotype in this family is distinct from other X linked recessive disorders linkage studies were carried out. Linkage analysis was done using X chromosome microsatellite polymorphisms to define the interval containing the causative gene. Genes from within the region were considered possible candidates and one of these, SYN1, was screened for mutations by direct DNA sequencing of amplified products. Microsatellite analysis showed that the region between MAOB (Xp11.3) and DXS1275 (Xq12) segregated with the disease. Two point linkage analysis demonstrated linkage with DXS1039, lod score 4·06 at θ = 0, and DXS991, 3·63 at θ = 0. Candidate gene analysis led to identification of a nonsense mutation in the gene encoding synapsin I that was present in all affected family members and female carriers and was not present in 287 control chromosomes. Synapsin I is a synaptic vesicle associated protein involved in the regulation of synaptogenesis and neurotransmitter release. The SYN1 nonsense mutation that was identified is the likely cause of the phenotype in this family.