Tracking the origin of HSP

Posted - November 2007 in Research Highlights

‘Founder effect’ suspected in French Canadians with SPG4 HSP. Findings suggest c.G1801A mutation in French Canadians originates from a common ancestor.

Background

The most common cause of autosomal dominant Hereditary Spastic Paraplegia (HSP) is mutations in the SPG4 gene. We have previously identified novel SPG4 mutations in a collection of North American families including the c.G1801A mutation present in two families from Quebec. The aim of this study is to estimate the frequency of the c.G1801A mutation in the French Canadian (FC) population and to determine whether this mutation originates from a common ancestor.

Methods

We collected and sequenced exon 15 in probands of 37 families. Genotypes of markers flanking the SPG4 gene were used to construct haplotypes in five families. Clinical information was reviewed by a neurologist with expertise in HSP.

Results

We have identified three additional unrelated families with the c.G1801A mutation and haplotype analysis revealed that all five families share a common ancestor. The mutation is present in 7% of all our FC families and explains half of our spastin linked FC families. The phenotype associated with the c.G1801A genotype is pure HSP with bladder involvement.

Conclusion

In this study we have determined that the relative frequency of the c.G1801A mutation in our FC collection is 7%, and approximately 50% in the spastin positive FC group. This mutation is the most common HSP mutation identified in this population to date and is suggestive of a founder effect in Quebec.

Source

Can J Neurol Sci. 2007 May;34(2):211-4.
SPG4 founder effect in French Canadians with hereditary spastic paraplegia.
Meijer IA, Dupré N, Brais B, Cossette P, St-Onge J, Rioux MF, Benard M, Rouleau GA.
Center for the Study of Brain Diseases, CHUM Research Center, Notre-Dame Hospital, Montreal, QC, Canada.
PMID: 17598600 [PubMed – indexed for MEDLINE]