Russell-Silver syndrome

Russell-Silver syndrome (RSS) is a genetic disorder that usually results from the abnormal regulation of certain genes that control growth.^[1] Two genetic causes have been found to result in about 60% of the cases:^[2][3]

• Abnormalities at an imprinted region on chromosome 11p15 - for some genes, only the copy inherited from a person's father (paternal copy) or mother (maternal copy) is "turned on," or expressed. These parent-specific differences in gene expression are caused by a phenomenon called genomic imprinting. Abnormalities involving genes that undergo imprinting are responsible for many cases of RSS.
• Maternal disomy of chromosome 7 (written as matUPD7) - this occurs when a child inherits both copies of chromosome 7 from the mother, instead of one copy from the mother and one copy from the father.

Most cases of Russell-Silver syndrome (RSS) are sporadic (not inherited), occurring in people with no family history of RSS.^[1]

Rarely, RSS may be inherited. In some families, it appears to be inherited in an autosomal dominant manner.^[3] This means that having a genetic change in only one copy of the responsible gene in each cell is enough to cause the disorder. In other families, RSS is inherited in an autosomal recessive manner.^[3] This means that to have RSS, a person must have a change in both copies of the responsible gene in each cell. Affected people inherit one copy from each parent, who is referred to as a carrier. Carriers of autosomal recessive conditions typically do not have any signs or symptoms (they are unaffected).

The chance for a person with Russell-Silver syndrome (RSS) to have an affected child depends on the genetic cause of RSS in the parent and the family history. In some cases, the genetic cause is not identified.

If a parent has RSS due to an imprinting defect on chromosome 11p15, the risk to his/her children is thought to be low. However to our knowledge, with the exception of one report of father-to-daughter transmission of the imprinting defect, no data to determine this exact risk are available.^[3]

If a parent has RSS due to maternal disomy of chromosome 7, the risk to his/her children is thought to be low. However in this case as well, there is no data we are aware of regarding exact recurrence risks.^[3]

View the information in our Inheritance Section for information on the recurrence risk when RSS is known to be an autosomal dominant or autosomal recessive disorder (which rarely occur).

Because most cases of RSS occur only in a single family member, most pregnancies are not considered to be at increased risk for the disorder.^[3] However, people with personal questions about the genetic cause of RSS and risks to family members are strongly encouraged to speak with a genetic counselor or other genetics professional. A genetics professional can help by:

• thoroughly evaluating the family history
• addressing questions and concerns
• assessing recurrence risks
• facilitating genetic testing if desired
• discussing reproductive options

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.