Birth defects

Feb 15 2018


ACCORDING to a WHO report, more than 300,000 infants are born with severe congenital anomalies every year and die within four weeks of birth. About 3-6 per cent are born with life-altering birth defects. While some of these are due to poor maternal health linked to poverty, exposure to pesticides and certain medications which can cause chromosomal aberrations, the major cause is linked to consanguinity — when parents are related by blood.

Consanguinity not only severely increases the prevalence of inherited blood disorders such as thalassaemia, haemophilia and sickle cell disorders, rare congenital conditions like Harlequin-type skin disease, but also severe recessive disorders such as Tay-Sachs, cystic fibrosis, congenital heart defects, diabetes, spinal muscular atrophy, albinism, hearing impairment, epilepsy, schizophrenia, physical and intellectual disabilities, and other neuro-degenerative conditions.

According to Hank Pellissier of the Institute of Ethics and Emerging Technologies, consanguinity is a deeply rooted cultural preference among one-fifth of the world population mostly in the Middle East, Asia and North Africa. As Arabs have the highest incidence rate, the Centre for Arab Genomic Studies was set up in 2003 to prevent genetic disorders arising from consanguinity. Every Persian Gulf state now requires genetic testing before marriage, and other countries are also encouraging such testing.

Pakistan reportedly has the highest consanguinity rate at about 70pc, due to tradition as well as monetary, emotional and psychological reasons. Such marriages are often viewed as a religious obligation, which they are not. Estimates show that 5pc of the population may have B-Thalassaemia. Treatment can include regular blood transfusions and iron chelation throughout the patient’s lifetime.

The perils of consanguinity are hardly recognised in Pakistan.

Haemophilia, meanwhile, affects approximately one in 10,000 people. People with haemophilia do not have enough clotting factor in their blood and can bleed at the slightest injury, causing permanent deformities, anaemia and isolation. According to the Pakistan Haemophilia Patients Welfare Society, 90pc of such people are not even diagnosed due to the country’s poor health infrastructure. Treatment is very expensive as the cost of one injection is approximately Rs8,000, and a severely affected patient may need up to 16 injections per month.

As shown in a study on an extended family in the Punjab, if parents are more closely related through inter-marriages, the risk of their offspring inheriting Homozygosity (ie possessing two identical forms of a particular gene, one inherited from each parent) is greatly increased. This can result in not only autosomal recessive diseases, but also produce rare discontinuous Mendelian mutations in which children are affected by diverse disorders such as epilepsy, schizophrenia and hearing impairment simultaneously.

Last March, doctors at a children’s hospital conference in Lahore strongly recommended that marriages between cousins and within clans and castes should be discouraged as the number of children suffering from a group of genetic diseases called lysosomal storage disorder is on the rise. LSD is caused by a defect in specific enzymes needed to break down waste products in the body. Palliative treatment of LSD is available but very expensive.

In Iran, a national premarital screening programme for thalassaemia was initiated in 1996. Within five years, it screened 2.7 million potential couples followed by genetic counselling of 10,000 couples who were found to be positive. This repo­r­­tedly resulted in a 70pc reduction in the expected an­­nual birth rate of affected infants. Cyprus has reduced the ratio of children born with thalassaemia to almost zero through similar preventive mea­sures.

The Ashkenazi Jews in Israel are known for their consanguinity and interbreeding. A study in Jerusalem cites a successful screening programme that was introduced in 1986 for the detection of Tay-Sachs disease carriers in this community to prevent marriages of couples with two heterozygotes (a hybrid containing genes for two unlike forms of a trait) and since then, no TSD child has been born to Ashkenazi couples in Israel.

Pakistan, like the proverbial ostrich, does not officially recognise the existence of this problem at the government level. In fact, the unrealistically low prevalence rates of disability persistently reported by the government have had a very negative impact on budgetary allocations for data collection, counselling, treatment, intervention, rehabilitation and research in this area.

The government needs to establish an official database for genome studies to assess the rate of inherited diseases in the country and take remedial action. It also needs to engage professionals, academics and religious bodies in the task of educating young people and their families about the possible hazards of consanguinity, custom and tradition notwithstanding.

The writer is a former federal secretary.

Published in Dawn, February 15th, 2018