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Specific podocin mutations correlate with age of onset in steroid-resistant nephrotic syndrome.

ABSTRACT: Mutations in the gene encoding podocin (NPHS2) cause autosomal recessive steroid-resistant nephrotic syndrome (SRNS). For addressing the possibility of a genotype-phenotype correlation between podocin mutations and age of onset, a worldwide cohort of 430 patients from 404 different families with SRNS were screened by direct sequencing. Recessive podocin mutations were present in 18.1% (73 of 404) of families with SRNS, and 69.9% of these mutations were nonsense, frameshift, or homozygous R138Q. Patients with these mutations manifested symptoms at a significantly earlier age (mean onset <1.75 years) than any other patient group, with or without podocin mutations, in this study (mean onset >4.17 yr). All but one patient affected by truncating or homozygous R138Q mutations developed SRNS before 6 yr of age. Patient groups with other recessive podocin mutations, with single heterozygous podocin mutations, with sequence variants, and with no podocin changes could not be distinguished from each other on the basis of age of onset. In conclusion, nephrotic syndrome in children with truncating or homozygous R138Q mutations manifests predominantly before 6 yr of life, and the onset of disease is significantly earlier than for any other podocin mutations. Because the age of onset can vary by several years among those with identical mutations, additional factors may modify the phenotype.

SUBMITTER: Hinkes B

PROVIDER: S-EPMC2396749 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature

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Specific podocin mutations correlate with age of onset in steroid-resistant nephrotic syndrome.

Hinkes Bernward B Vlangos Christopher C Heeringa Saskia S Mucha Bettina B Gbadegesin Rasheed R Liu Jinhong J Hasselbacher Katrin K Ozaltin Fatih F Hildebrandt Friedhelm F

Journal of the American Society of Nephrology : JASN 20080123 2

Mutations in the gene encoding podocin (NPHS2) cause autosomal recessive steroid-resistant nephrotic syndrome (SRNS). For addressing the possibility of a genotype-phenotype correlation between podocin mutations and age of onset, a worldwide cohort of 430 patients from 404 different families with SRNS were screened by direct sequencing. Recessive podocin mutations were present in 18.1% (73 of 404) of families with SRNS, and 69.9% of these mutations were nonsense, frameshift, or homozygous R138Q. ...[more]

PMID: 18216321

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Project description:BackgroundFew data exist for the genetic variants underlying the risk for steroid-sensitive nephrotic syndrome (SSNS) in children. The objectives of this study were to evaluate HLA-DQA1 and APOL1 variants as risk factors for SSNS in African American children and use classic HLA antigen types and amino acid inference to refine the HLA-DQA1 association.Study designCase-control study.Setting & participantsAfrican American children with SSNS or steroid-resistant nephrotic syndrome (SRNS) were enrolled from Duke University and centers participating in the Midwest Pediatric Nephrology Consortium.FactorGenetic variants in HLA-DQA1 (C34Y [rs1129740]; F41S [rs1071630]) and APOL1 high-risk alleles.OutcomesSSNS and SRNS.MeasurementsDirect sequencing for the HLA-DQA1 and APOL1 variants in 115 African American children (65 with SSNS and 50 with SRNS). Imputation of classic HLA alleles and amino acids was done in 363 South Asian children.ResultsThe 2 HLA-DQA1 variants were significantly associated with SSNS in African American children (C34Y: P=5.7 × 10-11; OR, 3.53; 95% CI, 2.33-5.42; F41S: P=1.2 × 10-13; OR, 4.08; 95% CI, 2.70-6.28), but not with SRNS (C34Y: P=0.6; F41S: P=0.2). APOL1 high-risk variants were not associated with SSNS (P=0.5) but showed significant associations with SRNS (P=1.04 × 10-7; OR, 4.17; 95% CI, 2.23-7.64). HLA-DQA1*0201, HLA-DQB1*0201, and HLA-DRB1*0701 were the classic HLA alleles with the most significant associations with SSNS risk. The most significantly associated amino acid positions were HLA-DQα1 56 and 76 (both P=2.8 × 10-7). Conditional analysis revealed that these variants most likely account for the observed association.LimitationsModest sample size and limited statistical power to detect small to moderate effect sizes. Children studied may not be representative of all African American children in the United States.ConclusionsHLA-DQA1 is a risk locus for SSNS, but not SRNS, in African American children, consistent with its role in SSNS risk in children of European, Asian, and African ancestries. There is little evidence of a significant role for the APOL1 high-risk alleles in childhood SSNS in African American children. Refinement of the HLA-DQA1 association identified the critical classic HLA antigen types and amino acids of the HLA-DQ α1 molecule.

Dataset Information

Specific podocin mutations correlate with age of onset in steroid-resistant nephrotic syndrome.

Publications

Specific podocin mutations correlate with age of onset in steroid-resistant nephrotic syndrome.

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