SPG4 founder effect in French Canadians with hereditary spastic paraplegia.
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.


CONCLUSIONS
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.
Meijer
Inge A
IA
Center for the Study of Brain Diseases, CHUM Research Center, Notre-Dame Hospital, Montreal, QC, Canada.
Dupré
Nicolas
N
Brais
Bernard
B
Cossette
Patrick
P
St-Onge
Judith
J
Rioux
Marie-France
MF
Benard
Melanie
M
Rouleau
Guy A
GA
D000251:Adenosine Triphosphatases / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D018703:Founder Effect; D005602:France / Q000208:ethnology; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D010375:Pedigree; D011792:Quebec; D015419:Spastic Paraplegia, Hereditary / Q000208:ethnology / Q000235:genetics*; D000074181:Spastin; D044465:White People / Q000235:genetics*
D000251:Adenosine Triphosphatases; D000074181:Spastin; C400283:SPAST protein, human