Genetic Carrier Screening – What? When? and How?

During any doctor’s appointment, one is oftentimes encountered with questions about family history and ethnic background. The reason being that there are several genetic conditions that are more common in specific ethnic and these conditions can be carried through multiple generations via genes.

What are genes?

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Genes are specific parts of DNA that contain the code or instruction that tells the body how to grow and develop. Genes are strings of information on DNA that is tightly coiled and packed into structures called chromosomes. There are 23 pairs of chromosomes in every cell of a human body – one set of chromosomes are inherited from the mother and other set from the father. Consequently,, each gene has two copies, one copy is inherited from the mother and the other is inherited from the father.

What are recessive diseases?

Many conditions are now known to be caused by changes, or mutations, in genes. In a recessive diseases, the change or mutation is present on both copies of the gene. This means both the mother and father are silent carriers the same change in the gene and have passed it to the child.

Who is a carrier?

Every individual had two working copies of each gene. In a carrier, one copy of the gene is non-working (because of a mutation) and the other copy works normally. A carrier does have one copy of the defective gene but do not exhibit the disease trait. In many families, a recessive gene change or trait is passed on through several generations silently without being known. A recessive disease can only occur if a person who is a carrier has a baby with another person who is also a carrier. Such a couple would have a 1 in 4 (25 percent) chance, in each pregnancy, of having a baby with that recessive disease. Please see the figure below –

autosomal chartWho should be screened?

DNA tests are available to help a couple determine if they are carriers of a recessive disease trait and are at risk for having children with that recessive condition. Some diseases occur more often in certain ethnic groups.

Identifying one’s carrier status is important while planning to have a baby as this has direct implications for the health of the child.
If both parents are found to be carriers of the same disease, they have a 1 in 4 chance of having an affected baby (for autosomal recessive disorders) and may choose prenatal genetic testing to make informed decisions during pregnancy.

Some important facts

“Genetic disorders come in all shapes and sizes and are often undiagnosed or diagnosed too late due to lack of awareness around genetic testing and its benefits,” said Dr. Robert Desnick, Professor and Chairman of the Department of Genetics and Genomic Sciences at the Mount Sinai School of Medicine and Medical Advisor to the Genetic Disease Foundation. Studies show Sickle cell hemoglobin alone ranges from 17% to 30% or more in the population. Hb E is dominant in the eastern half of the Indian sub-continent, and in some areas, carrier rates exceed 60% of the population! The carrier frequency for β thalassaemia ranges from 0.3% to 15%, while that for the minor form of α thalassaemia varies from 15% to 80% in north eastern parts of India. Every year there are about 500,000 children born with genetic disorders in India alone! Birth Defects Registry of India (BDRI), has recorded 2.5/1000 are born with Neural Tube Defects. A vast number of children also die within the first week of their birth, primarily because their diseases were not detected early? Screening can help you in informing and identifying risks in future children by predicting genetic disorders as early as possible. Most metabolic disorders can be managed by early detection!

BabyMap from Mapmygenome offers genetic screening for 171 conditions. The targeted conditions were chosen with high scrutiny to provide a list that once detected, could be managed early and ensure a healthy baby. Early detection is key for successful treatment and management. BabyMap provides results at lightning speed to help confirm diagnosis, learn about high risk diseases and possibly detect it early as possible.

 


Some of the way we can help a bit more than others are –

  • Broad coverage; covers all metabolic diseases on the American College of Medical Genetics (ACMG) recommended panel
  • Quick Turnaround time
  • Provide clients with genetic testing accessibility, specifically next generation sequencing
  • CLIA accredited Clinical diagnostic lab partner with the ability to quickly design, develop and validate new tests

Why should YOU choose Babymap?

  • Highly cost effective
  • Quick turn around time
  • Over 16 years of experience in Genomics
  • Latest sequencing platforms
  • Personalised Genetic Counseling