MULTAN: Researchers working on families curtailing genetic diseases, particularly albinism, have identified a novel locus and 11 novel mutations (permanent change in the sequence of DNA) in already reported four albinism genes that will help them diagnose albinism in Pakistani population and develop its therapy.

The principal investigators include Dr Rehan Sadiq Sheikh, associate professor at the Institute of Molecular Biology and Biotechnology of Bahauddin Zakariya University, and Dr Zubair Ahmad from the Cincinnati Children Hospital, Ohio, US, while Prof Dr Muhammad Ali and two PhD students of Dr Sheikh are co-principal investigators in the research.

Dr Sheikh told Dawn that lustrous white skin is the result of lack of pigment from the skin resulting into a congenital disorder called albinism with an incidence rate of approximately one out of 20,000 worldwide.

He said albinism could also cause vision problems and that the disease could also be found in animals and plants.He said that no epidemiological study for albinism had been conducted in Pakistan while variation in skin, hair and iris (a thin, circular structure in the eye) colour is remarkable and visible character in different human populations.

“Skin pigmentation is an extremely multifarious human feature ranging from white or pink to tan, dark brown or black,” he said.

He said albinism was an inherited disease and family history was the only known risk factor of the disorder. In the case of recessive albinism, if one of the parents is a carrier, there is a 50 per cent chance of inheriting one defective gene in each child.

“However, if both parents are carriers, each child has a 25 per cent chance of inheriting two defective genes while one out of four children will probably have the disorder,” he said.

He said approximately 60 per cent of marriages in Pakistan are consanguineous, of which more than 80 per cent are between first cousins.

He said such a large consanguineous families could turn up to increase the prevalence of recessively inherited genetic disorders like albinism while in families with known history of the disease, prenatal testing could be executed to resolve the presence of the problem in the fetus.

“We are working on families curtailing genetic diseases to resolve the jigsaw puzzle of proteins involved in genetic diseases and till now we have enrolled 200 families affected with the disease,” he said.

He said his team had identified 17 pathogenic mutations, in four albinism genes including TYR (OCA1), OCA2, TYRP1 and SLC45A2 out of which 11 mutations are novel that are causing albinism in 30 families in southern Punjab.

“For the first time in Pakistani population, three novel mutations are identified in TYR gene (OCA1), four in OCA2, one in TYRP1 and three in SLC45A2,” he said.

He said they had also identified a novel locus/gene OCA5 causing albinism in a family, while cause of almost 20 enrolled families was under investigation,” he said.

Published in Dawn, July 12th, 2014