Fine mapping of an imprinted gene for familial nonchromaffin paragangliomas, on chromosome 11q23
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Baysal, BE; Farr, JE; Rubinstein, WS; Galus, RA; Johnson, KA; Aston, CE; Myers, EN; Johnson, JT; Carrau, R; Kirkpatrick, SJ; Myssiorek, D; Singh, D; Saha, S; Gollin, SM; Evans, GA; James, MR; Richard, CW
Abstract
Hereditary nonchromaffin paragangliomas (PGL; glomus tumors; MIM 168000) are mostly benign, slow-growing tumors of the head and neck region, inherited from carrier fathers in an autosomal dominant fashion subject to genomic imprinting. Genetic linkage analysis in two large, unrelated Dutch families assigned PGL loci to two regions of chromosome 11, at 11q23 (PGL1) and 11q13.1 (PGL2). We ascertained a total of 11 North American PGL families and confirmed maternal imprinting (inactivation). In three of six families, linkage analysis provided evidence of linkage to the PGL1 locus at 11q23. Recombinants narrowed the critical region to an similar to 4.5-Mb interval flanked by markers D11S1647 and D11S622. Partial allelic loss of strictly maternal origin was detected in 5 of 19 tumors. The greatest degree of imbalance was detected at 11q23, distal to D11S1327 and proximal to CD3D. Age at onset of symptoms was significantly different between fathers and children (Wilcoxon rank-sum test, P < .002). Affected children had an earlier age at onset of symptoms in 39 of 57 father-child pairs (chi(2) = 7.74, P < .006). However, a more conservative comparison of the number of pairs in which a child had greater than or equal to 5 years earlier age at onset (n = 33) vis-a-vis that of complementary pairs (n = 24) revealed no significant difference (chi(2) = 1.42, P > .2). Whether these data represent genetic anticipation or ascertainment bias can be addressed only by analysis of a larger number of father-child pairs.
A major determinant quantitative-trait locus responsible for atonic dermatitis-like skin lesions in NC/Nga mice is located on Chromosome 9
IMMUNOGENETICS
Authors: Kohara, Y; Tanabe, K; Matsuoka, K; Kanda, N; Matsuda, K; Karasuyama, H; Yonekawa, H
Abstract
NC/Nga (NC) is a newly discovered model mouse for human atopic dermatitis, NC mice showing specific symptoms such as dermatitis and overproduction of IgE. To detect the loci responsible for the onset of dermatitis in the mice, backcross (N2) progeny between (NCxMSM/MS)F1 and NC were generated, where MSM/MS is an inbred strain from Japanese wild mice, Mus musculus molossinus. Linkage disequilibrium between dermatitis and various chromosome-specific microsatellite markers was then examined in the N2 segregants with severe dermatitis. The analysis revealed that the locus of the major determinant (designated here as derm1) was tightly linked to D9Mit163, D9Mit72, D9Mit143, D9Mit103, D9Mit207, and D9Mit209, because these markers showed the highest and most significant chi (2) values. Since no recombination was observed among the markers in our linkage map, a radiation hybrid (RH) panel was applied to locate the derm1 locus more precisely. The markers were separated on the RH map, and their order was D9Mit163-D9Mit72-D9Mit143D9Mit103-D9Mit207-D9Mit209 from the centromere. Several functional candidate genes are located near the locus derm1. These candidates are Thy1, Cd3d, Cd3e, Cd3g, Il10ra, Il18, and Csk, all of which could be involved in allergic responses through effects on T-cell function. Of these candidates, Csk is the strongest for NC dermatitis, since its map position was most tightly linked to the derm1 locus.