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Clinical and molecular cytogenetic characterization of two patients with non‐mutational aberrations of the FMR2 gene
Author(s) -
Honda Shozo,
Hayashi Shin,
Kato Mitsuhiro,
Niida Yo,
Hayasaka Kiyoshi,
Okuyama Torayuki,
Imoto Issei,
Mizutani Shuki,
Inazawa Johji
Publication year - 2007
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.31638
Subject(s) - xq28 , genetics , breakpoint , fluorescence in situ hybridization , cytogenetics , chromosomal fragile site , biology , microbiology and biotechnology , x chromosome , karyotype , chromosomal translocation , gene , chromosome
We report on two patients; a female having mild mental retardation (MR) with a balanced translocation, 46,XX,t(X;15)(q28;p11.2), and a male diagnosed as having mucopolysaccharidosis type II (MPS II or Hunter syndrome) with atypical early‐onset MR and a normal male karyotype. Molecular cytogenetic analyses, including fluorescence in situ hybridization and array‐based comparative genomic hybridization using an in‐house X‐tiling array, revealed that first patient to have a breakpoint at Xq28 lying within the FMR2 gene and the second to have a small deletion at Xq28 including part of FMR2 together with the IDS gene responsible for MPS II. In Patient 1, X‐chromosome inactivation predominantly occurred in the normal X in her lymphocytes, suggesting that her MR might be explained by a disruption of the FMR2 gene on der(X) t(X;15) concomitant with the predominant inactivation of the intact FMR2 gene in another allele. We compared phenotypes of Patient 2 with those of MPS II cases with deletion of the IDS gene alone reported previously, suggesting that the early‐onset MR might be affected by the additional deletion of FMR2 . © 2007 Wiley‐Liss, Inc.