Family History Assessment

A family history of birth defects and/or genetic conditions can influence the health of the current pregnancy. As previously discussed, testing may be available for dominant, recessive or sex-linked genetic diseases.  Some couples have a family history of problems due to multifactorial traits or structural chromosome rearrangements. During your appointment, a detailed family history will be taken and a genetic counselor will discuss the assessment with you.

MULTIFACTORIAL TRAITS:

The most common birth defects are those that occur due to the complex interactions and combinations of maternal, environmental and genetic influences. These birth defects are usually called multifactorial traits, referring to the many different factors that come together to cause the problem. For example, congenital heart defects and cleft lip are usually multifactorial conditions. Almost 1 child in 150 is born with a congenital heart defect and 1 in 500 with cleft lip. Another multifactorial condition is spina bifida, a type of an open neural tube defect. Spina bifida occurs in approximately 1 or 2 in 1000 births. Taking the vitamin folic acid (folate) helps reduce the chance of having a baby with spina bifida. In most cases predictive genetic testing is not available for multifactorial traits, however a family history assessment may provide more accurate recurrence risks.

STRUCTURAL CHROMOSOME ABNORMALITIES:

Random changes in the number of chromosomes can occur in any pregnancy (see age related risks). A second type of chromosome abnormality is a change in the structure or organization of the chromosomes. These changes include deletions (a small missing piece), inversions (a piece flipped upside down), insertions (an added piece) or translocations (exchange of pieces involving two or more chromosomes). Structural changes are not associated with maternal age. They can be the cause of multiple unexplained miscarriages, birth defects or apparent infertility.