I explained to them that every pregnancy has SOME risk for genetic abnormality. This risk is expected to be in the range of 2-5%. The risk is SLIGHTLY increased and maybe up to 6-10% in a marriage between blood relatives or in a “consanguineous” marriage. In other words, in consanguineous marriage, upto 90-95% pregnancies result in healthy babies.

I explained that each parent (through their sperm or ovum) passes 23 chromosomes and a single copy of about 25000 genes to their offspring. These chromosomes and genes carry all the genetic information for baby for lifetime. If both the copies of a single gene, inherited from each parent is carrying a defect, there will be no normal copy of that gene and a disease may manifest related to that specific gene. This phenomenon is known as “autosomal recessive” inheritance.

Consanguineous marriages are typically at slightly higher risk for these conditions. These autosomal recessive disorders appear in children, ONLY when each parent, out of their two copies carries one defective copy, also known as “carriers”. Advanced genetic testing in the form of “Whole exome sequencing” is available to identify carrier status for the important genetic disorders. This test screens genetic defects in about 2000 important genes. The report provides information about those genes and conditions, for which both partners are carriers and hence their babies might be at risk for such autosomal recessive disorders. Its important to note that each person is a “carrier” for genetic defects in 3-5 genes. These defects are relevant for pregnancies ONLY when the partner is also carrying the defect in the SAME gene.

After counseling, the family agreed to do the genetic testing and they both were detected to be carriers for TGM1 gene, a gene which is known to be associated with congenital ichthyosis, characterised by extreme dry skin and sometimes neurological abnormalities in the baby. The couple was told that there was a 25% chance that each of their future pregnancies may be affected with congenital ichthyosis. For future pregnancies they were advised to undergo prenatal testing at about 3 months.

After the post-test counseling, the parents seemed to relax and the couple happily asked just one question - Can we marry now?