Some special needs are the result of genetics and can be traced through family medical history. Many times though, parents are unaware of the risk of their child having a birth defect.

Birth Defects Found in Extended Family

A birth defect might be passed on from previous generations, although it might not be immediately recognized as such because it does not show up in Mom, Dad, or even grandparents. Hemophilia is a condition that can be passed on by a baby's mother although she has no evidence of the condition herself. Because it is conveyed through the X chromosome, her sons have a chance of manifesting hemophilia.

Birth Defects Due to Autosomal Recessive Inheritance

Perhaps both parents have the recessive gene for a particular disability. Any of their children who receive recessive genes from both parents will have the condition or disease. There is a 25 percent chance that a baby whose parents both have a recessive gene for a condition will manifest that condition.

Examples of autosomal recessive inheritance conditions include cystic fibrosis, PKU, galactosemia, sickle cell disease, albinism, and Tay-Sachs disease.

Birth Defects Due to Autosomal Dominant Inheritance

Some birth defects result from inheriting a single, dominant gene. If one parent has a dominant gene for a particular condition or disease, it may be passed on and manifested in the child. Marfan syndrome, Huntington disease, and at least one form of dwarfism are examples of autosomal dominant inheritance.

Genetic Counseling

Couples planning to have a baby may seek genetic counseling. In fact, usually early consultation with an obstetrician-gynecologist will include completion of a questionnaire on family medical history. If there is an indication that genetic risks exist, it is critical to seek more extensive genetic counseling. Such counseling might include asking extended family members to complete health questionnaires or certain medical screenings and lab tests for one or both parents.