An interstitial deletion-insertion involving chromosomes 2p25.3 and Xq27.1, near SOX3, causes X-linked recessive hypoparathyroidism
Michael R. Bowl, … , Michael P. Whyte, Rajesh V. Thakker
Michael R. Bowl, … , Michael P. Whyte, Rajesh V. Thakker
Published October 3, 2005
Citation Information: J Clin Invest. 2005;115(10):2822-2831. https://doi.org/10.1172/JCI24156.
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Research Article Genetics

An interstitial deletion-insertion involving chromosomes 2p25.3 and Xq27.1, near SOX3, causes X-linked recessive hypoparathyroidism

Abstract

X-linked recessive hypoparathyroidism, due to parathyroid agenesis, has been mapped to a 906-kb region on Xq27 that contains 3 genes (ATP11C, U7snRNA, and SOX3), and analyses have not revealed mutations. We therefore characterized this region by combined analysis of single nucleotide polymorphisms and sequence-tagged sites. This identified a 23- to 25-kb deletion, which did not contain genes. However, DNA fiber–FISH and pulsed-field gel electrophoresis revealed an approximately 340-kb insertion that replaced the deleted fragment. Use of flow-sorted X chromosome–specific libraries and DNA sequence analyses revealed that the telomeric and centromeric breakpoints on X were, respectively, approximately 67 kb downstream of SOX3 and within a repetitive sequence. Use of a monochromosomal somatic cell hybrid panel and metaphase-FISH mapping demonstrated that the insertion originated from 2p25 and contained a segment of the SNTG2 gene that lacked an open reading frame. However, the deletion-insertion [del(X)(q27.1) inv ins (X;2)(q27.1;p25.3)], which represents a novel abnormality causing hypoparathyroidism, could result in a position effect on SOX3 expression. Indeed, SOX3 expression was demonstrated, by in situ hybridization, in the developing parathyroid tissue of mouse embryos between 10.5 and 15.5 days post coitum. Thus, our results indicate a likely new role for SOX3 in the embryonic development of the parathyroid glands.

Authors

Michael R. Bowl, M. Andrew Nesbit, Brian Harding, Elaine Levy, Andrew Jefferson, Emanuela Volpi, Karine Rizzoti, Robin Lovell-Badge, David Schlessinger, Michael P. Whyte, Rajesh V. Thakker

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Identification of a less than 28-kb deletion on chromosome Xq27.1 in X-l...
Identification of a less than 28-kb deletion on chromosome Xq27.1 in X-linked recessive HPT patients. The disease locus is located between the SNP rs5907612 and the microsatellite polymorphism DXS984 (9), which are shown on the expanded view alongside the schematically represented X chromosome with Giemsa bands. This 906-kb critical interval contains 3 genes — ATP11C, U7snRNA, and SOX3 — and abnormalities involving the coding regions of these genes in X-linked recessive HPT patients has been previously excluded (9). To further reduce the critical interval, SNPs from the telomeric boundary were initially sought, and analysis of the contig comprising BACs RP11-359I11, RP11-51C14, and RP4-595A18 revealed 2 SNPs, rs732125 and rs461191, that were respectively located approximately19 kb and 8 kb centromeric to U7snRNA. SNP rs461191 proved uninformative in the X-linked recessive HPT kindreds. However, analysis with SNP rs732125 revealed a likely deletion, as PCR products were not obtained from the 6 affected males (filled square) but were obtained from the 16 unaffected males (open square), 11 carrier females (circle with a dot), and 28 unaffected females (data not shown). This deletion was further delineated using 5 STSs (a–e) that were designed at intervals along the sequence of BAC RP11-51C14. PCR products were obtained using STSs a and e but not STSs b, c, and d, thereby indicating that the deletion extended from STS a to STS e, an interval of less than 28 kb.