Six new mutations of the thyroglobulin gene discovered in taiwanese children presenting with thyroid dyshormonogenesis.
BACKGROUND
Thyroglobulin (TG) defect is a rare cause of congenital hypothyroidism. Although only 44 mutations of the human TG gene have been identified, we have suspected a TG defect in 38% of Taiwan Chinese children/adolescents presenting with moderate or severe thyroidal dyshormonogenesis.


OBJECTIVE
The aim of the study is to report the discovery of new TG gene mutations and associated clinical manifestations of the defective TG protein.


RESULTS
In seven patients from six families, we detected six new TG gene mutations, including c.1348delT, p.R432X (c.1351C>T), g.IVS3 + 2T>G, c.1712delT, p.Q1765X (c.5350C>T), and c.6047delA. The c.1348delT and p.R432X mutations were the most common, detected in 33 and 25%, respectively, of alleles studied. Haplotype analysis suggested that the c.1348delT and g.IVS3 + 2T>G mutations are due to founder effects, whereas p.R432X is probably due to independently recurrent de novo mutations. mRNA transcript of the g.IVS3 + 2T>G mutant, detected in whole blood by reverse transcription-nested PCR, showed skipping of exon 3 (98-bp deletion) and a frameshift, with a terminal signal after 17 altered amino acid residues.


CONCLUSIONS
TG defects have an important role in severe thyroidal dyshormonogenesis (pretreatment, or after a 3-wk T(4) withdrawal, plasma T(4) < or = 30 nmol/liter) in Taiwanese. Its genetic characteristics are markedly different from those described in other populations presenting with mutations of the TG gene.
Niu
Dau-Ming
DM
Institute of Clinical Medicine, National Yang-Ming University, Taipei 112, Taiwan. dmniu1111@yahoo.com.tw
Hsu
Ju-Hui
JH
Chong
Kah-Wai
KW
Huang
Cheng-Hung
CH
Lu
Yung-Hsiu
YH
Kao
Chuan-Hong
CH
Yu
Hsiao-Chi
HC
Lo
Ming-Yu
MY
Jap
Tjin-Shing
TS
D000293:Adolescent; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D009154:Mutation / Q000235:genetics / Q000502:physiology; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D013624:Taiwan; D013954:Thyroglobulin / Q000235:genetics*; D050033:Thyroid Dysgenesis / Q000235:genetics*; D013960:Thyroid Function Tests
D012333:RNA, Messenger; D013954:Thyroglobulin