Genetic Linkage

INTRODUCTION: Nocturnal enuresis affects 15-20% of 5-year-old children, 5% of 10 year-old-children and 1-2% of people aged 15 years and over. Without treatment, 15% of affected children will become dry each year. Nocturnal enuresis is not diagnosed in children younger than 5 years, and treatment may be inappropriate for children younger than 7 years. METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions for relief of symptoms?

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.

Substantial evidence supports the familial aggregation of exceptional longevity. The existence of rare families demonstrating clustering for this phenotype suggests that a genetic etiology may be an important component. Previous attempts at localizing loci predisposing for exceptional longevity have been limited to association studies of candidate gene polymorphisms. In this study, a genome-wide scan for such predisposing loci was conducted by using 308 individuals belonging to 137 sibships demonstrating exceptional longevity.

Recently, chromosome 4q25 was linked to exceptional human longevity, and a haplotype of the positional candidate microsomal transfer protein (MTP) gene was associated to the phenotype in U.S. Caucasians. We investigated whether linkage to 4q25 could be detected in 164 nonagenarian sibships of the Leiden Longevity Study. Additionally, we compared the MTP -493G/T and Q95H allele and haplotype frequencies in the Leiden Longevity Study (379 nonagenarians, 525 of their offspring, and 251 partners of their offspring) and in the Leiden 85-Plus Study (655 octogenarians and 244 young controls).

BACKGROUND: Human lifespan is approximately 25% heritable, and genetic factors may be particularly important for achieving exceptional longevity. Accordingly, siblings of centenarians have a dramatically higher probability of reaching extreme old age than the general population. METHODOLOGY/PRINCIPAL FINDINGS: To map the loci conferring a survival advantage, we performed the second genomewide linkage scan on human longevity and the first using a high-density marker panel of single nucleotide polymorphisms.

BACKGROUND: Although there is abundant evidence that human longevity is heritable, efforts to map loci responsible for variation in human lifespan have had limited success. METHODOLOGY/PRINCIPAL FINDINGS: We identified individuals from a large multigenerational population database (the Utah Population Database) who exhibited high levels of both familial longevity and individual longevity. This selection identified 325 related "affected individuals", defined as those in the top quartile for both excess longevity (EL?

BACKGROUND: Although there is abundant evidence that human longevity is heritable, efforts to map loci responsible for variation in human lifespan have had limited success. METHODOLOGY/PRINCIPAL FINDINGS: We identified individuals from a large multigenerational population database (the Utah Population Database) who exhibited high levels of both familial longevity and individual longevity. This selection identified 325 related "affected individuals", defined as those in the top quartile for both excess longevity (EL?

Clear evidence exists for heritability of human longevity, and much interest is focused on identifying genes associated with longer lives. To identify such longevity alleles, we performed the largest genome-wide linkage scan thus far reported. Linkage analyses included 2118 nonagenarian Caucasian sibling pairs that have been enrolled in 15 study centers of 11 European countries as part of the Genetics of Healthy Aging (GEHA) project.

Bivariate survival models with discretely distributed frailty based on the major gene concept and applied to the data on related individuals such as twins and sibs can be used to estimate the underlying hazard, the relative risk and the frequency of the longevity allele. To determine the position of the longevity gene, additional genetic markers data are needed. If the action of the longevity allele does not depend on its position in the genome, these two problems can be solved separately using a two-step procedure.

A tandemly repeated DNA hexanucleotide sequence, 5'C-C-C-C-A-A3', that occurs at the termini of extrachromosomal DNA molecules coding for rRNA (rDNA) in Tetrahymena macronuclei was examined to determine whether it is packaged as nucleosomes. This repeated DNA sequence comprises the terminal few hundred base pairs at each end of the linear rDNA molecules.