Medical Genetics: Multifactorial Inheritance
What is multifactorial inheritance?
Multifactorial inheritance is when more than one factor causes a trait or health problem,
such as a birth defect or chronic illness. The main factor is genes. But the cause
includes other factors that aren’t genes, such as:
Alcohol and tobacco
Often one sex—males or females—is affected more often than the other for certain traits
Risks that run in the family
Multifactorial conditions tend to run in families. This is because they are partly
caused by genes. Your risk for a multifactorial trait or condition depends on how
close you are to a family member with the trait or condition.
For example, you’re at higher risk for a trait or disorder if your brother or sister
has it. You’re at lower risk if a cousin has it. Family members share a portion of
genes in common, depending upon their place in the family tree. Your parents, siblings,
and children share about half of your genes. But because multifactorial disorders
are caused by more than one factor, it’s hard to pin down a person’s real risk of
having it or passing it on.
Types of multifactorial traits and disorders
Health problems that are caused by both genes and other factors include:
Birth defects such as neural tube defects and cleft palate
Cancers of the breast, ovaries, bowel, prostate, and skin
High blood pressure and high cholesterol
Skin conditions such as psoriasis, moles, and eczema
Asthma and allergies
Multiple sclerosis and other autoimmune disorders
Learning your risks
If you have family members with any of the above health conditions, talk with your
healthcare provider about your risks. He or she can give you information about how
to lower your risk for certain conditions, or how to manage a condition.