Which are the causes of Russell Silver Syndrome?

Russell Silver Syndrome (RSS) is a rare genetic disorder primarily caused by epigenetic changes that affect gene expression related to growth, rather than changes to the DNA sequence itself. In approximately 60% of cases, the condition is linked to the loss of methylation on chromosome 11p15, while about 10% of cases are caused by maternal uniparental disomy of chromosome 7.

What causes Russell Silver Syndrome at the genetic level?

The pathophysiology of Russell Silver Syndrome is centered on genomic imprinting, a process where genes are expressed differently depending on which parent they are inherited from. Think of it like a biological "switch" that is supposed to be turned on by one parent but is accidentally left off. In Russell Silver Syndrome, the most common mechanism involves the loss of DNA methylation at the H19/IGF2 imprinting control region on chromosome 11. This prevents the normal expression of the IGF2 gene, a critical growth factor, leading to the characteristic intrauterine and postnatal growth restriction seen in patients.

Are there different types of genetic triggers for Russell Silver Syndrome?

While the majority of cases involve chromosome 11, there are distinct genetic pathways identified in clinical research:

• Hypomethylation of H19/IGF2 (11p15): Accounts for roughly 60% of cases.


• Maternal Uniparental Disomy (mUPD) of Chromosome 7: Accounts for approximately 10% of cases, where a child inherits two copies of chromosome 7 from the mother instead of one from each parent.


• Unknown Etiology: In about 30% of individuals clinically diagnosed with Russell Silver Syndrome, the underlying genetic or epigenetic cause remains unidentified despite advanced testing.

Is Russell Silver Syndrome hereditary?

Most cases of Russell Silver Syndrome are sporadic, meaning they occur randomly and are not inherited from parents. Because the molecular mechanisms involve epigenetic changes rather than permanent mutations in the germline, the recurrence risk for siblings of an affected child is generally very low. However, clinical geneticists emphasize that families should still undergo formal genetic counseling to assess their specific situation.

What is the current state of research into Russell Silver Syndrome?

Researchers are actively investigating the 30% of cases where the cause remains elusive, using whole-genome sequencing to look for rare structural variants or novel imprinting defects. With 263 members in the DiseaseMaps.org community, patient-reported data continues to help researchers understand the phenotypic variability of Russell Silver Syndrome, bridging the gap between clinical observation and molecular discovery.

Next steps

• Consult with a clinical geneticist to discuss molecular testing options.


• Connect with the 263 members of the Russell Silver Syndrome community at DiseaseMaps.org to share experiences.


• Request a referral to a pediatric endocrinologist for specialized growth management.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Russell Silver Syndrome


• Orphanet: Silver-Russell Syndrome (ORPHA:814)


• OMIM (Online Mendelian Inheritance in Man): Silver-Russell Syndrome (#180860)


• The MAGIC Foundation: Russell Silver Syndrome Educational Resources