Vol. 12, Issue 6, 956-961, June 2002

LETTER
Extended Intermarker Linkage Disequilibrium in the Afrikaners

¹ The Rockefeller University, Human Neurogenetics Laboratory, New York, New York 10021, USA; ² University of Washington, Division of Medical Genetics, Department of Medicine; and Department of Biostatistics, Seattle, Washington 98195, USA; ³ University of Pretoria Department of Psychiatry & Weskoppies Hospital, Pretoria, 0083, Republic of South Africa; ⁴ Columbia University, College of Physicians & Surgeons, Department of Physiology and Cellular Biophysics and Center for Neurobiology & Behavior, New York, New York 10032, USA.

In this study we conducted an investigation of the background level of linkage disequilibrium (LD) in the Afrikaner population to evaluate the appropriateness of this genetic isolate for mapping complex traits. We analyzed intermarker LD in 62 nuclear families using microsatellite markers covering extended chromosomal regions. The markers were selected to allow the first direct comparison of long-range LD in the Afrikaners to LD in other demographic groups. Using several statistical measures, we find significant evidence for LD in the Afrikaners extending remarkably over a 6-cM range. In contrast, LD decays significantly beyond 3-cM distances in the other founder and outbred populations examined. This study strongly supports the appropriateness of the Afrikaner population for genome-wide scans that exploit LD to map common, multigenic disorders.