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IDENTIFICATION OF THREE NOVEL MUTATIONS IN THE GATA3 GENE RESPONSIBLE FOR FAMILIAL HYPOPARATHYROIDISM AND DEAFNESS IN THE CHINESE POPULATION

W-Y Chiu, ¹H-W Chen, H-W Chao, L-T Yann, K-S Tsai

Department of Laboratory Medicine and Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan, and ¹Department of Internal Medicine, Lo-Tung Pohai Hospital, Ilan, Taiwan

Background: Familial hypoparathyroidism may be caused by mutations of several genes. The CaSR and GATA3 genes are the two candidates most commonly responsible for this condition.

Objectives: We collected 5 unrelated families with familial hypoparathyroidism, and examined their CaSR and GATA3 genes.

Methods: Blood samples from these 5 families and 50 ethnically matched unrelated controls were acquired. Biochemistry screening and formal audiogram were performed to evaluate the affected individuals. All the exons and exon-intron boundaries of the GATA3 and CaSR genes were sequenced.

Results: We identified three novel mutations in the GATA3 gene responsible for familial hypoparathyroidism and deafness. (1) A frameshift deletion occurring in codon 160 (478delG) was hypothesized to disrupt dual zinc fingers as well as one transactivating domain. (2) A donor splice site mutation at exon 4/intron 4 boundary (IVS4+2 T to GCTTACTTCCC) was predicted to lead to truncated GATA3 proteins that lack both N-terminal and C-terminal zinc-containing fingers. (3) A missense mutation R353S was predicted to disrupt the helical turn and thus changed the angle between the C-terminal zinc finger and the adjacent C-terminal tail. Except for a previously described polymorphism, G990R, we did not find any genetic variants in CaSR gene

Conclusions: This is the first article presenting mutations of the GATA3 gene responsible for familial hypoparathyroidism and deafness in the Chinese population. Our results expand the spectrum of mutations and report the first splice donor site mutation of GATA3 gene. In contrast, we do not find causal sequence variants of the CaSR gene from our collection of familial hypoparathyroidism.