• Overview
• Inheritance
• Symptoms
  • Liver and Spleen
  • Lungs
• Testing
• Treatment
• Resources

All types of NPD are inherited in an autosomal recessive pattern and can affect both males and females. The disease occurs when both copies of a person's acid sphingomyelinase gene have a mutation (a change in a gene which causes it to work incorrectly). Carriers have one normal gene copy and one gene copy with a mutation; carriers do NOT have NPD. Being a carrier of NPD is not known to lead to any health problems. Less than 1% of people are type B NPD carriers.

A person with NPD inherits one gene mutation from each parent, both of whom are carriers. Each child of two carrier parents has: a 25% chance of being unaffected and not a carrier (having two working copies of the gene), a 50% chance of being a NPD carrier (having one working copy of the gene, like his/her parents), and a 25% chance of having NPD (having no working copies of the gene).

Blood relatives (siblings, aunts/uncles, cousins, etc.) of patients with NPD may also be carriers of a NPD gene mutation.

If one parent has type B NPD, and the other parent is not affected and is not a NPD carrier, then all of their children will be carriers but will not have NPD.

If one parent has type B NPD, and the other is a carrier, in each pregnancy there is a 50% chance that the child will have NPD and a 50% chance that the child will be a NPD carrier.

The different details of each family history will cause the risk figures and other genetic counseling issues to vary from family to family. The specific information for YOUR family will be covered during the genetic counseling consultation part of your evaluation at the Center.