© 2018, GENASSIST, Inc.     

By Keith S. Wexler, MBA, Maternal Fetal Medicine, Prenatal Diagnosis and Biotech/Life Sciences Consultant, GENASSIST, Inc.

Paul Wexler, M.D., F.A.C.O.G., Medical Director, GENASSIST, Inc.

Clinical Professor, Department of OB/GYN, University of Colorado Health Sciences Center

Clinical Professor, Division of Genetics/Dept. of Pediatrics, Univ. of Colorado/The Children’s Hospital

Background: We saw a 29 year old female Gravida 0 Para 0 SAB 0 EAB 0 who is considering having children with her husband and wanted to discuss their risks for a child with a medical problem because they are 1st cousins (Consanguinity) from Morocco. 

Consanguinity depending upon geographical region (i.e. Morocco) is a feature of between 20-28% of all marriages with 50% between first cousins. Approximately 59% of families with individuals with autosomal recessive diseases [inheriting one disease (deleterious) gene from each parent] are “related”.

Consanguinity can cause significant burdens to some families:

  • Birth defects
  • Inborn errors of metabolism
  • Mitochondrial disease (inherited from the mother)
  • Primary immunodeficiency
  • Other inherited diseases
  • Cancer

The number of newborns born with a genetic disease from Consanguinity is approximately 5%.  These conditions include:

  • Congenital skeletal malformations
  • Heart defects
  • Hemophilia
  • Autism
  • Type I diabetes
  • Sexual differentiation disorders
  • Eye and ear problems
  • Metabolic disorders

Microarray Testing can detect carriers of many autosomal recessive diseases and can identify some duplications and deletions. A positive test should initiate similar testing in the other parent or presumptive parent of a child. 

A negative test does NOT rule out carrier status for all patients nor does it rule out the possible interaction between a mutation found and other mutations or genes or mutations not studied.

Rarely the same disorder or a similar disorder (phenocopy) can result from a different cause and possibly even the inheritance of the same abnormal mutation or gene from a single parent (isodisomy).