Functional analysis of thyroid peroxidase gene mutations detected in patients with thyroid dyshormonogenesis.
Thyroid peroxidase (TPO) is the key enzyme in the biosynthesis of thyroid hormones. We aimed to identify the spectrum of mutations in the TPO gene leading to hypothyroidism in the population of West Bengal to establish the genetic etiology of the disease. 200 hypothyroid patients (case) and their corresponding sex and age matched 200 normal individuals (control) were screened depending on their clinical manifestations. Genomic DNA was isolated from peripheral blood samples and TPO gene (Exon 7 to Exon 14) was amplified by PCR. The PCR products were subjected to sequencing to identify mutations. Single nucleotide changes such as Glu 641 Lys, Asp 668 Asn, Thr 725 Pro, Asp 620 Asn, Ser 398 Thr, and Ala 373 Ser were found. Changes in the TPO were assayed in vitro to compare mutant and wild-type activities. Five mutants were enzymatically inactive in the guaiacol and iodide assays. This is a strong indication that the mutations are present at crucial positions of the TPO gene, resulting in inactivated TPO. The results of this study may help to develop a genetic screening protocol for goiter and hypothyroidism in the population of West Bengal.
Post Graduate Department of Zoology, Barasat Government College, Barasat, Kolkata 700 124, India.
Srikanta
S
Guria
Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, West Bengal 700 019, India.
Biswabandhu
B
Bankura
Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, West Bengal 700 019, India.
Nisha
N
Balmiki
Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, West Bengal 700 019, India.
Arup Kumar
AK
Pattanayak
Bagnan Rural Hospital, Bagnan, Howrah, West Bengal 711 303, India.
Tapas Kumar
TK
Das
Department of Endocrinology, Institute of Post Graduate Medical Education & Research, 244 A J C Bose Road, Kolkata 700 020, India.
Anirban
0000-0001-6689-9707
A
Sinha
Institute of Life Sciences, Nalco Square, Chandra Sekharpur, Bhubaneswar 751 023, India.
Sudipta
S
Chakrabarti
Bagnan Rural Hospital, Bagnan, Howrah, West Bengal 711 303, India.
Subhankar
S
Chowdhury
Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, West Bengal 700 019, India.
Madhusudan
M
Das