Breast cancer is the most common cancer of women worldwide. The Global Cancer Project provides evidence that 20,88,849 (11.6% of all cancers) new cases of breast cancer were identified around the world in the year 2018 and 6,26,679 deaths (6.6% of all cancer deaths) occurred in the same year (Globocan, 2018). It is predicted that the new cases of breast cancer patients will reach up to 22 million in next two decades (Ghoncheh et al., 2016). Like Western countries, it is now growing strongly in Asia and has become the leading cause of death among women (Story et al., 2011). Many human diseases, including breast cancer, are caused by genetic defect and in the recent years, researchers and scientists are investigating the genetic cause for understanding the course of these diseases as well as for finding the way of their prevention and

Context and rationale: Congenital hypothyroidism is a prevalent endocrine disease that may occur due to the alteration in the sequence of nucleotides of the NKX2.5 gene. Though congenital hypothyroidism is quite common among the Bangladeshi pediatric population, there are few studies on the genetic basis of this disease. Objective: This study aimed to identify any mutation in the exon2 of the NKX2.5 gene in Bangladeshi pediatric patients with congenital hypothyroidism. Methods: Forty (40) Bangladeshi pediatric patients with congenital hypothyroidism were recruited, the sociodemographic data were collected and analyzed, DNA was isolated, quantity and quality of DNA were checked, polymerase chain reaction (PCR) was done, the amplicons were visually validated by gel electrophoresis and cycle sequencing was done by Sanger sequencing. The raw chromatogram data were analyzed and compared with the NCBI database by BLAST (Basic Local Alignment Search Tool) search. Results: Sanger sequencing revealed two types of alteration in the nucleotide sequence. Nine patients showed substitutions (c.1051G>T) and eight patients showed deletions (c.1143 delT-), and both substitution and deletion were present in four patients. This substitution and deletion occurred in the Sequence Tagged Site (STS) of the exon2 of the NKX2.5 gene and these are new variants and not reported in NCBI database. Conclusion: In the present study, two types of variants were identified. So, further study to find out mutational status among Bangladeshi children might be helpful in enriching the database of mutational spectra of pediatric patients with congenital hypothyroidism.

Abstract