Regional and ethnic distribution of beta thalassemia mutations and effect of consanguinity in patients referred for prenatal diagnosis.
OBJECTIVE
To determine the regional and ethnic distribution of beta thalassemia mutation and the effect of consanguinity in patients referred for prenatal diagnosis of beta b-thalassemia and to target the high risk population for screening.


METHODS
Cross-sectional, analytical study.


METHODS
The study was conducted in Gentec Laboratory, Lahore, from January 2001 to December 2005.


METHODS
A total of 499 couples were referred to Gentec Lab., Lahore, from all over Pakistan for prenatal diagnosis of b-thalassemia. After counseling, chorionic villus sampling was done between 10-16 weeks of gestation. DNA analysis was done by Amplification Refractory Mutation System (ARMS) for type of mutation in the Armed Forces Institute of Pathology, Rawalpindi. Ethnicity, race and consanguineous relationship of parents was determined.


RESULTS
b-thalassemia was prevalent in Punjabis (60.7%) followed by Saraikees (25.5%). Castewise it was most frequent in Rajputs followed by Jatts, Arain, Sheikhs and Pathans. 56.7% of the couples were first cousins and 19.8% were relatives. The commonest mutations were Frameshift 8-9 (Fr8-9) 33.5%, Intervening Sequence 1-5 (IVS 1-5) 17.2%, Fr4142 - 8%, IVS 1-1 - 5.2%, Deletion 619 (Del 619) 4.2% and Codon 5 (Cd 5) - 4.2%. In samples sent for analysis, 53.1% turned out to be carriers (trait), 25.3% were diseased (thalassemia major) and 21.6% were normal. P-value of all results was less than 0.001.


CONCLUSIONS
In this series, the highest frequency was found in Punjabi Rajputs. The commonest mutation was Fr 8-9. Most parents were first cousins. Premarital thalassemia carrier testing can effectively reduce the disease.
Hafeez
Maimoona
M
Department of Obs/Gynae, Lahore Medical and Dental College, Lahore. maimoonahafeez_pk@yahoo.com
Aslam
Maleeha
M
Ali
Ayesha
A
Rashid
Yasmin
Y
Jafri
Hussain
H
D003241:Consanguinity; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009154:Mutation; D010154:Pakistan; D011247:Pregnancy; D011296:Prenatal Diagnosis; D017086:beta-Thalassemia / Q000175:diagnosis / Q000208:ethnology / Q000235:genetics*