A founder mutation in the PEX6 gene is responsible for increased incidence of Zellweger syndrome in a French Canadian population.
BACKGROUND
Zellweger syndrome (ZS) is a peroxisome biogenesis disorder due to mutations in any one of 13 PEX genes. Increased incidence of ZS has been suspected in French-Canadians of the Saguenay-Lac-St-Jean region (SLSJ) of Quebec, but this remains unsolved.


METHODS
We identified 5 ZS patients from SLSJ diagnosed by peroxisome dysfunction between 1990-2010 and sequenced all coding exons of known PEX genes in one patient using Next Generation Sequencing (NGS) for diagnostic confirmation.


RESULTS
A homozygous mutation (c.802_815del, p.[Val207_Gln294del, Val76_Gln294del]) in PEX6 was identified and then shown in 4 other patients. Parental heterozygosity was confirmed in all. Incidence of ZS was estimated to 1 in 12,191 live births, with a carrier frequency of 1 in 55. In addition, we present data suggesting that this mutation abolishes a SF2/ASF splice enhancer binding site, resulting in the use of two alternative cryptic donor splice sites and predicted to encode an internally deleted in-frame protein.


CONCLUSIONS
We report increased incidence of ZS in French-Canadians of SLSJ caused by a PEX6 founder mutation. To our knowledge, this is the highest reported incidence of ZS worldwide. These findings have implications for carrier screening and support the utility of NGS for molecular confirmation of peroxisomal disorders.
Department of Pediatrics, Université de Sherbrooke, Sherbrooke, Canada. sebastien.a.levesque@usherbrooke.ca
Sebastien
S
Levesque
Charles
C
Morin
Simon-Pierre
SP
Guay
Josee
J
Villeneuve
Pascale
P
Marquis
Wing Yan
WY
Yik
Sarn
S
Jiralerspong
Luigi
L
Bouchard
Steven
S
Steinberg
Joseph G
JG
Hacia
Ken
K
Dewar
Nancy E
NE
Braverman
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000235:genetics*; D001483:Base Sequence; D005260:Female; D018703:Founder Effect; D005602:France / Q000208:ethnology; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D009154:Mutation; D011792:Quebec / Q000453:epidemiology; D044465:White People / Q000235:genetics*; D015211:Zellweger Syndrome / Q000201:enzymology / Q000453:epidemiology* / Q000235:genetics*
D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C490759:PEX6 protein, human