1% of Couples at Risk of Having Child with Severe Genetic Condition

According to a recent paper published in the American Journal of Human Genetics, one out of every 100 European couples is at risk of having a child affected with an autosomal-recessive (AR) genetic condition. Genes are passed on from parent to child therefore we have two copies of each gene. If both parents pass on a non-working copy of the same gene to their child, they will have an autosomal-recessive genetic condition. 

The study looked at DNA of 6,447 individuals of two distinct European ancestries who are genetically unrelated and healthy. They found that individuals carry on average two AR mutations or variants in known genes.

A few important points highlighted in the study include:

• Approximately 1% of European couples not related by blood are at risk of having a child with a severe recessive genetic condition.
• For first cousins, the risk of having an affected child is 16.5-fold higher.
• The two populations studied have their own variants, but they show striking resemblance of overall carrier frequencies for different disorders.

The researchers simulated all possible matings from the two groups virtually. For couples not related by blood, a limited number of genes is the main cause of recessive genes. Therefore, increasing the number of genes on carrier screens will not greatly increase detection.

This information will help guide future decisions around carrier screening as the same conclusions can be applied to evaluate any population.

How Carrier Screening Helps

Healthy Individuals are not typically aware that they carry a non-working gene. This is where carrier screening can help couples determine if they are at risk of having a child with a recessive genetic condition.

LifeLabs Genetics’ Expanded Carrier Screening (ECS) analyzes up to 289 different hereditary conditions. Between 2-2.5% of couples who proceed with this testing are expected to be carriers of the same condition. For more information on our Expanded Carrier Screening test, please visit our Expanded Carrier Screening page.

References

1. The landscape of autosomal-recessive pathogenic variants in European populations reveals phenotype-specific effects, American Journal of Human Genetics. https://www.cell.com/ajhg/fulltext/S0002-9297(21)00088-4
2. Study Shows 1 Percent of European Couples at Risk of Having Child With Severe Recessive Disorder, GenomeWeb. https://www.genomeweb.com/reproductive-health/study-shows-1-percent-european-couples-risk-having-child-severe-recessive