Genetic correlates of longevity and selected age-related phenotypes: a genome-wide association study in the Framingham Study

Background

Family studies and heritability estimates provide evidence for a genetic contribution to variation in the human life span.

Methods

We conducted a genome wide association study (Affymetrix 100K SNP GeneChip) for longevity-related traits in a community-based sample. We report on 5 longevity and aging traits in up to 1345 Framingham Study participants from 330 families. Multivariable-adjusted residuals were computed using appropriate models (Cox proportional hazards, logistic, or linear regression) and the residuals from these models were used to test for association with qualifying SNPs (70, 987 autosomal SNPs with genotypic call rate ≥80%, minor allele frequency ≥10%, Hardy-Weinberg test p ≥ 0.001).

Results

In family-based association test (FBAT) models, 8 SNPs in two regions approximately 500 kb apart on chromosome 1 (physical positions 73,091,610 and 73, 527,652) were associated with age at death (p-value < 10^-5). The two sets of SNPs were in high linkage disequilibrium (minimum r² = 0.58). The top 30 SNPs for generalized estimating equation (GEE) tests of association with age at death included rs10507486 (p = 0.0001) and rs4943794 (p = 0.0002), SNPs intronic to FOXO1A, a gene implicated in lifespan extension in animal models. FBAT models identified 7 SNPs and GEE models identified 9 SNPs associated with both age at death and morbidity-free survival at age 65 including rs2374983 near PON1. In the analysis of selected candidate genes, SNP associations (FBAT or GEE p-value < 0.01) were identified for age at death in or near the following genes: FOXO1A, GAPDH, KL, LEPR, PON1, PSEN1, SOD2, and WRN. Top ranked SNP associations in the GEE model for age at natural menopause included rs6910534 (p = 0.00003) near FOXO3a and rs3751591 (p = 0.00006) in CYP19A1. Results of all longevity phenotype-genotype associations for all autosomal SNPs are web posted at http://www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?id=phs000007.

Conclusion

Longevity and aging traits are associated with SNPs on the Affymetrix 100K GeneChip. None of the associations achieved genome-wide significance. These data generate hypotheses and serve as a resource for replication as more genes and biologic pathways are proposed as contributing to longevity and healthy aging.

     

A clinical study of infants presenting to a mental retardation clinic

Early detection has a central role in the prevention and management of mental retardation. The purpose of this present study is to delinerate the characteristics of developmentally delayed infants and their families attending Mental Retardation Clinic. The sample consisted of 101 infants who were registered in Mental Retardation Clinic of NIMHANS, Bangalore in 1988 constituting 12.5% of total registrations. Data was collected from case records. Majority of subjects were males, first or second born, 7 months or older, from a consanguineous lower or middle class family. Along with developmental delay, 60% had other complaints. Medical problems were reported in about half of the subjects and most had abnormalities on physical examination. Aetiology was discernible in 77.1%. Majority had associated physical disorder such as cerebral palsy, seizures and hearing and/or visual impairment. Around 17% came for follow-up thrice or more, 43% dropped out after work-up. The main conclusions are that; (i) certain socio-demographic, personal and clinical variables influence treatment seeking, and (ii) developmental delay recognised in infancy tends to be associated with clear aetiologic factors and significant medical/neurologic problems.     

Myelofibrosis and renal osteodystrophy

A young patient with chronic renal failure, pancytopenia and hepatosplenomegaly with hypersplenism had evidence of severe renal osteodystrophy on x-ray films and a bone marrow biopsy specimen resembling myelofibrosis. Hematologic improvement followed splenectomy and was sustained following renal transplantation.