X-Linked syndrome of polyendocrinopathy, immune dysfunction, and diarrhea maps to Xp11.23-Xq13.3

Abstract

We describe genetic analysis of a large pedigree with an X-linked syndrome of polyendocrinopathy, immune dysfunction, and diarrhea (XPID), which frequently results in death during infancy or childhood. Linkage analysis mapped the XPID gene to a 17-cM interval defined by markers DXS8083 and DXS8107 on the X chromosome, at Xp11. 23-Xq13.3. The maximum LOD score was 3.99 (recombination fraction0) at DXS1235. Because this interval also harbors the gene for Wiskott-Aldrich syndrome (WAS), we investigated mutations in the WASP gene, as the molecular basis of XPID. Northern blot analysis detected the same relative amount and the same-sized WASP message in patients with XPID and in a control. Analysis of the WASP coding sequence, an alternate promoter, and an untranslated upstream first exon was carried out, and no mutations were found in patients with XPID. A C-->T transition within the alternate translation start site cosegregated with the XPID phenotype in this family; however, the same transition site was detected in a normal control male. We conclude that XPID maps to Xp11.23-Xq13.3 and that mutations of WASP are not associated with XPID.

Figure 1

K1768, a five-generation pedigree segregating an X-linked gene for XPID. Two affected males used for northern blot analysis are indicated by asterisks (*). Haplotypes for markers within the X-chromosome bands Xp11.23–Xq13.3 are shown. A crossover distal to marker DXS8083 in individual II-5 defines a proximal flanking marker for XPID. A second recombination seen in the same individual (II-5) and in II-7 occurred distal to DXS1275, defining DXS8107 as the distal flanking marker for the XPID gene region.

Figure 2

Multilocus analysis, with the XPID gene against fixed genetic map of linked markers (Généthon). The highest probability for location of XPID is in the region DXS426–DXS1235.

Figure 3

Genetic localization of the XPID locus to Xp11.23–Xq13.3. The horizontal bar indicates the XPID candidate interval at ∼17 cM averaged over the three genetic maps of CEPH (Fondation Jean Dausset/CEPH), Généthon, and the Center for Medical Genetics, Marshfield Medical Research Foundation. The relative location of a 1.1-Mb sequence-ready cosmid contig (Schindelhauer et al. 1996) is indicated at markers DXS6941–DXS1039, a region also harboring WASP.

Figure 4

Northern blot analysis of WASP in XPID and control RNA. Lanes 1 and 2 contain RNA from B-lymphoblastoid cell lines derived from XPID patients; lane 3 contains RNA control. The probe used was a PCR product generated by amplification of normal genomic DNA with primers 5.16 and 5.17 spanning exons 1 and 2 of WASP. A control hybridization with β-actin cDNA is also shown (bottom). For autoradiograms, the exposure time for the WASP message was 7 d; for the β-actin control, it was overnight. The ratio of hybridization signals for the WASP message (2.1 kb) versus the β-actin message is ∼0.1, for both patients with XPID and for a control cell line.

Figure 5

NspI site analysis of the WASP alternate promoter fragment. Lane 1; 700 ng 100 bp marker (Gibco BRL); lanes 1–3, 5, 9, and 12 homozygous Nsp I−; lanes 4 and 8 hemizygous Nsp I+; and lanes 6, 7, 10, and 11 heterozygous Nsp I+/Nsp I− carrier females within this XPID pedigree.