A high observed substitution rate in the human mitochondrial DNA control region.

The rate and pattern of sequence substitutions in the mitochondrial DNA (mtDNA) control region (CR) is of central importance to studies of human evolution and to forensic identity testing. Here, we report a direct measurement of the intergenerational substitution rate in the human CR. We compared DNA sequences of two CR hypervariable segments from close maternal relatives, from 134 independent mtDNA lineages spanning 327 generational events.

A linkage study of bipolar illness.

Background: Although genetic epidemiological studies of bipolar (BP) illness are consistent with a heritable component, inherited risk factors remain unknown. The goal of the present study is to describe the localization of BP susceptibility loci through linkage strategies, including a genome-wide search.

Methods: A linkage study of 22 BP families has been performed.

Affected-sib-pair analyses reveal support of prior evidence for a susceptibility locus for bipolar disorder, on 21q.

In 22 multiplex pedigrees screened for linkage to bipolar disorder, by use of 18 markers on chromosome 21q, single-locus affected-sib-pair (ASP) analysis detected a high proportion (57%-62%) of alleles shared identical by descent (IBD), with P values of .049-.0008 on nine marker loci.

Adrenocorticotropin receptor/melanocortin receptor-2 maps within a reported susceptibility region for bipolar illness on chromosome 18.

We have examined the possible linkage of adrenocorticotropin receptor/melanocortin receptor-2 (ACTHR/MC-2) to a reported putative susceptibility locus for bipolar illness (BP) in 20 affected pedigrees. Initially, allelic variants of the gene were identified by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) and the gene was genetically mapped using both the Centre d'Etudes du Polymorphisme Humain (CEPH) pedigrees and the BP pedigrees used in this study. We found that the ACTHR/MC-2 gene maps between D18S53 and D18S66.

Genetic linkage mapping for a susceptibility locus to bipolar illness: chromosomes 2, 3, 4, 7, 9, 10p, 11p, 22, and Xpter.

We are conducting a genome search for a predisposing locus to bipolar (manic-depressive) illness by genotyping 21 moderate-sized pedigrees. We report linkage data derived from screening marker loci on chromosomes 2, 3, 4, 7, 9, 10p, 11p, 22, and the pseudoautosomal region at Xpter. To analyze for linkage, two-point marker to illness lod scores were calculated under a dominant model with either 85% or 50% maximum penetrance and a recessive model with 85% maximum penetrance, and two affection status models.