Linkage analysis using platelet-activating factor Ca2+ response in transformed lymphoblasts

Epstein-Barr virus-transformed lymphoblasts from patients with essential hypertension demonstrate enhanced G protein-mediated cytosolic free calcium ([Ca2+]i) response to platelet-activating factor (PAF). To map genes responsible for variation in G protein-coupled signaling, we used this cellular phenotype for a linkage study of transformed cell lines from the Centre d'Etude du Polymorphisme Humain (CEPH) reference pedigrees. The PAF-evoked change in [Ca2+]i ranged from 20 to 392 mmol/L and was highly reproducible within each cell line. PAF-elicited [Ca2+]i responses were obtained in lymphoblastic cell lines from five densely mapped pedigrees of the CEPH collection. Using PAF-evoked [Ca2+]i responses as a quantitative trait, two-point sibpair linkage analyses were conducted using 5150 markers from the Collaborative Human Linkage Center (CHLC) database. Nine loci, located on chromosomes 1, 4, 10, 11, 13, 16, and 17, were suggestive of linkage, with values of P < 7.4 x 10(-4). Multipoint linkage analysis produced a significant linkage finding (P = 2.1 x 10(-5) in one family at D16S151, with suggestive linkage results for seven additional markers spanning a 40-cM interval of chromosome 16. Multipoint analysis produced suggestive findings of linkage to eight loci from two distinct regions of chromosome 11 in another family. These results indicate that loci involved in the control of G protein-mediated mechanisms, suggested to be involved in the pathophysiology of essential hypertension, can be identified using cell lines from general pedigrees selected without any knowledge of the blood pressure status of the donors. This strategy represents an approach to rapidly and inexpensively mapping loci related to common, complex disorders, using phenotypes that are stable in immortalized lymphoblasts together with existing reference pedigree cell lines and genotype databases.