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A novel missense homozygous inactivating mutation in the fourth transmembrane helix of the luteinizing hormone receptor in leydig cell hypoplasia
Author(s) -
Leung Michael YiuKwong,
AlMuslim Osama,
Wu ShaoMing,
Aziz Andrew,
Inam Sohail,
Awadh Mohammed,
Rennert Owen M.,
Chan WaiYee
Publication year - 2004
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.20681
Subject(s) - missense mutation , biology , mutation , medicine , endocrinology , hek 293 cells , microbiology and biotechnology , receptor , genetics , gene
Loss‐of‐function mutations/inactivating mutations of the human chorionic gonadotropin/luteinizing hormone receptor (hCG/LHR), a G‐protein coupled receptor, lead to impaired Leydig cell differentiation. Leydig cell hypoplasia/agenesis/dysplasia (LCH) is one of the causes of male pseudohermaphroditism (MPH). We studied a 19‐year‐old MPH patient with female phenotype and 46,XY karyotype. Testicular histology and hormonal profile of the patient is typical of LCH. Nucleotide sequencing of exon 11 of hLHR identified a novel T1505C transversion mutation. The mutation is homozygous in the patient and is heterozygous in both parents. The single base mutation caused the substitution of a conserved leucine at 502 position to proline in transmembrane helix (TM) IV of the hLHR. This is the first LCH causing mutation identified in TM IV of the hLHR. Expression study of the mutated hLHR in human embryonic kidney (HEK)293 cells showed reduced cAMP production and ligand binding. Receptor trafficking was not affected by the mutation when the green fluorescence protein conjugated mutated receptor was expressed in HEK293 cells. The mutation caused inactivation of the hLHR and resulted in LCH in the patient. © 2004 Wiley‐Liss, Inc.