Robinow syndrome

Robinow syndrome may be inherited in an autosomal recessive or autosomal dominant manner.^[1]

Autosomal recessive (AR) inheritance means both copies of the responsible gene in each cell must have a mutation for a person to be affected. The parents of a person with AR Robinow syndrome usually each carry one mutated copy of the gene and are referred to as carriers. Carriers typically are unaffected. When two carriers of AR Robinow syndrome have children together, each child has a 25% (1 in 4) chance to be affected, a 50% (1 in 2) chance to be an unaffected carrier like each parent, and a 25% chance to be unaffected and not a carrier.

Autosomal dominant (AD) inheritance means that having only one mutated copy of the responsible gene in each cell is enough to cause features of the condition. Some people with AD Robinow syndrome inherit the mutated gene from an affected parent. In other cases, the mutation that causes the condition occurs for the first time in the affected person.^[1] When a person with AD Robinow syndrome has children, each child has a 50% chance to inherit the mutated gene.

The genetic risks to siblings of a person with Robinow syndrome depend on whether the affected person has autosomal dominant Robinow syndrome, or autosomal recessive Robinow syndrome.

At conception (when the egg is fertilized), each sibling of a person with autosomal recessive (AR) Robinow syndrome has a 25% (1/4) chance to be affected, a 50% (1/2) chance of being a carrier (usually with no symptoms), and a 25% chance of being unaffected and not a carrier. However, once the sibling of a person with AR Robinow syndrome is confirmed to be unaffected, the risk to be a carrier is about 67% (2/3). A person with one mutated copy of the responsible gene also has a 2/3 chance to have brachydactyly type B1 (which causes shortened digits), another condition caused by certain types of mutations in the same gene.^[2]

When a person has autosomal dominant Robinow syndrome, the risk to each of his/her siblings at conception depends on the genetic status of the parents. If a parent is affected, the risk for each sibling to be affected is 50%. When both parents appear to be unaffected, the risk to the siblings appears to be low. It is not possible to be an unaffected carrier of autosomal dominant Robinow syndrome; having one mutated copy of the responsible gene causes features of the condition.^[3]

People with questions or concerns about genetic risks to themselves or family members are encouraged to speak with a genetics professional.

Genetic testing for autosomal recessive Robinow syndrome and autosomal dominant Robinow syndrome is available. However, not all people diagnosed with either type of Robinow syndrome have mutations in the genes known to cause these conditions. In these cases, the cause remains unknown. Carrier testing for autosomal recessive Robinow syndrome is possible if the disease-causing mutations have been identified in an affected family member.

The Genetic Testing Registry (GTR) provides information about the genetic tests for Robinow syndrome. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.