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

×

Figure 4

Options: View larger image (or click on image) Download as PowerPoint
FISH analyses confirm the deletion-insertion involving Xq27.1 and 2p25 i...
FISH analyses confirm the deletion-insertion involving Xq27.1 and 2p25 in X-linked recessive HPT. (A) Metaphase-FISH analysis, using 2p25 fosmid AG63A8 (green signal) and Xq27 BAC RP11-51C14 (red signal). Chromosomes counterstained with DAPI (blue), and arrows indicate chromosomes 2 and X, as well as and abnormal X containing insert from 2p25 (X+2). Insets show enlarged views of X chromosome. Juxtaposed signals of fosmid and BAC, at Xq27, due to the deletion-insertion, yielded the yellow color. (B) Use of 3-color DNA fiber–FISH analyses revealed a large insertion that was derived from 2p25, at Xq27 in affected males. DNA fibers were hybridized with 2p25 YAC 972C12 (size, 750 kb), and the Xq27 BACs (Figure 1) RP11-51C14 (size, 149 kb) and RP11-359I11 (size, 43 kb). YAC 972C12 was labeled with fluorescein, BAC RP11-51C14 with Alexa-594, and BAC RP11-359I11 with Cy5, to yield green, red, and far red (pseudocolored in blue) signals, respectively. The numbers of observed DNA fibers yielding signals are indicated. (C) Contig of BACs (solid bars) and fosmid (broken bar) for YAC 972C12. (D) BACs were labeled with Texas red and separately hybridized to metaphase chromosome spreads. Two red signals corresponding to 2p25 hybridizations (white arrows) were obtained for each BAC (data shown for BACs RP11-97B21, CTD-2029L3, and RP13-542C4), and a third signal corresponding to Xq27 hybridizations (yellow arrows) was also detected for BACs CTD-2029L3, RP11-1268F2 (data not shown), and RP13-542C4. These results indicate that the insertion at Xq27.1 is contained between CTD-2029L3 and RP13-542C4 and is approximately 305–340 kb in size. The identification code used for individuals is as described in Figure 2.