GUWAHATI: Members of the world’s largest blind family, which lives in Assam’s Nagaon district, are visually challenged due to a hereditary disorder, health experts have found. The family has 18 blind members running across four generations.
There are only four such families in the world that suffer from this rare form of blindness caused by a mutation of the GJA8 gene, doctors who have been investigating the cause said. The other three families with the same disorder were discovered by University of Sydney Genetic Laboratory.
“Now that the cause has been identified, every pregnancy should be tested for the presence of the gene. If found, they will have to go for termination as per law. The selection of unborn members will gradually reduce the burden and after a few decades, the defect will disappear,” principal coordinator of the project and assistant professor of pathology, Dr Gayatri Gogoi, told
TOI
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Gogoi added that family planning and counselling for antenatal testing of the pregnant is a must in order to get rid of the gene.
Dr Gogoi’s team had a series of discussions with local officials as to how to cover the expenditure of genetic testing as it would cost around Rs 10,000 each time. However, the biggest predicament is that the existing facilities under Ayusman Bharat or Atal Amrit Abhiyan cannot be used for these kinds of rare diseases.
“We have achieved most of our scientific objectives. But, the immediate need is to cover the cost of antenatal genetic testing as only that will ensure that the coming generations get to lead normal lives,” Dr Gogoi said. Of late, while one pregnancy was found normal, another had to be terminated because of the presence of the gene.
Elaborating on how her project started, the doctor said until February 2018, nobody recognized the unique case of the family who earned their livelihood by begging. “When I came to know about the family, I explored that it must have a hereditary mystery,” she added.
During the course of the research, they found that the family members do not have fully-developed eyeballs in the socket or an underdeveloped structure — a medical condition referred to as anopthalmos and micropthalmos. They shortlisted genes and test samples were collected in Guwahati for genetic testing after pre-test counselling by them. As expected three members of the family from three different generations — Abdul Wahid, Khairul Islam and Somala Khatoon — tested positive for the pathogenic variant heterozygous which caused the genetic mutation leading to blindness.