TY - JOUR
T1 - Phenotypic and Functional Analysis of Human SLC26A6 Variants in Patients With Familial Hyperoxaluria and Calcium Oxalate Nephrolithiasis
AU - Monico, Carla G.
AU - Weinstein, Adam
AU - Jiang, Zhirong
AU - Rohlinger, Audrey L.
AU - Cogal, Andrea G.
AU - Bjornson, Beth B.
AU - Olson, Julie B.
AU - Bergstralh, Eric J.
AU - Milliner, Dawn S.
AU - Aronson, Peter S.
N1 - Funding Information:
Support: Research funding was received from Grants DK 64865 (Dr Monico), DK 73354 (Dr Milliner), and DK 33793 (Dr Aronson) from the National Institutes of Health and the Oxalosis and Hyperoxaluria Foundation (Dr Milliner).
PY - 2008/12
Y1 - 2008/12
N2 - Background: Urinary oxalate is a major risk factor for calcium oxalate stones. Marked hyperoxaluria arises from mutations in 2 separate loci, AGXT and GRHPR, the causes of primary hyperoxaluria (PH) types 1 (PH1) and 2 (PH2), respectively. Studies of null Slc26a6-/- mice have shown a phenotype of hyperoxaluria, hyperoxalemia, and calcium oxalate urolithiasis, leading to the hypothesis that SLC26A6 mutations may cause or modify hyperoxaluria in humans. Study Design: Cross-sectional case-control. Setting & Participants: Cases were recruited from the International Primary Hyperoxaluria Registry. Control DNA samples were from a pool of adult subjects who identified themselves as being in good health. Predictor: PH1, PH2, and non-PH1/PH2 genotypes in cases. Outcomes & Measures: Homozygosity or compound heterozygosity for SLC26A6 variants. Functional expression of oxalate transport in Xenopus laevis oocytes. Results: 80 PH1, 6 PH2, 8 non-PH1/PH2, and 96 control samples were available for SLC26A6 screening. A rare variant, c.487C→T (p.Pro163Ser), was detected solely in 1 non-PH1/PH2 pedigree, but this variant failed to segregate with hyperoxaluria, and functional studies of oxalate transport in Xenopus oocytes showed no transport defect. No other rare variant was identified specifically in non-PH1/PH2. Six additional missense variants were detected in controls and cases. Of these, c.616G→A (p.Val206Met) was most common (11%) and showed a 30% reduction in oxalate transport. To test p.Val206Met as a potential modifier of hyperoxaluria, we extended screening to PH1 and PH2. Heterozygosity for this variant did not affect plasma or urine oxalate levels in this population. Limitations: We did not have a sufficient number of cases to determine whether homozygosity for p.Val206Met might significantly affect urine oxalate. Conclusions: SLC26A6 was effectively ruled out as the disease gene in this non-PH1/PH2 cohort. Taken together, our studies are the first to identify and characterize SLC26A6 variants in patients with hyperoxaluria. Phenotypic and functional analysis excluded a significant effect of identified variants on oxalate excretion.
AB - Background: Urinary oxalate is a major risk factor for calcium oxalate stones. Marked hyperoxaluria arises from mutations in 2 separate loci, AGXT and GRHPR, the causes of primary hyperoxaluria (PH) types 1 (PH1) and 2 (PH2), respectively. Studies of null Slc26a6-/- mice have shown a phenotype of hyperoxaluria, hyperoxalemia, and calcium oxalate urolithiasis, leading to the hypothesis that SLC26A6 mutations may cause or modify hyperoxaluria in humans. Study Design: Cross-sectional case-control. Setting & Participants: Cases were recruited from the International Primary Hyperoxaluria Registry. Control DNA samples were from a pool of adult subjects who identified themselves as being in good health. Predictor: PH1, PH2, and non-PH1/PH2 genotypes in cases. Outcomes & Measures: Homozygosity or compound heterozygosity for SLC26A6 variants. Functional expression of oxalate transport in Xenopus laevis oocytes. Results: 80 PH1, 6 PH2, 8 non-PH1/PH2, and 96 control samples were available for SLC26A6 screening. A rare variant, c.487C→T (p.Pro163Ser), was detected solely in 1 non-PH1/PH2 pedigree, but this variant failed to segregate with hyperoxaluria, and functional studies of oxalate transport in Xenopus oocytes showed no transport defect. No other rare variant was identified specifically in non-PH1/PH2. Six additional missense variants were detected in controls and cases. Of these, c.616G→A (p.Val206Met) was most common (11%) and showed a 30% reduction in oxalate transport. To test p.Val206Met as a potential modifier of hyperoxaluria, we extended screening to PH1 and PH2. Heterozygosity for this variant did not affect plasma or urine oxalate levels in this population. Limitations: We did not have a sufficient number of cases to determine whether homozygosity for p.Val206Met might significantly affect urine oxalate. Conclusions: SLC26A6 was effectively ruled out as the disease gene in this non-PH1/PH2 cohort. Taken together, our studies are the first to identify and characterize SLC26A6 variants in patients with hyperoxaluria. Phenotypic and functional analysis excluded a significant effect of identified variants on oxalate excretion.
KW - SLC26A6
KW - calcium oxalate urolithiasis
KW - hyperoxaluria
UR - http://www.scopus.com/inward/record.url?scp=56049089361&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=56049089361&partnerID=8YFLogxK
U2 - 10.1053/j.ajkd.2008.07.041
DO - 10.1053/j.ajkd.2008.07.041
M3 - Article
C2 - 18951670
AN - SCOPUS:56049089361
SN - 0272-6386
VL - 52
SP - 1096
EP - 1103
JO - American Journal of Kidney Diseases
JF - American Journal of Kidney Diseases
IS - 6
ER -