Summary about Disease
Russell-Silver syndrome (RSS) is a rare genetic disorder characterized primarily by intrauterine growth restriction (IUGR) and/or postnatal growth failure, leading to short stature. Other common features include a distinctive facial appearance, body asymmetry, and feeding difficulties in infancy. The severity of symptoms can vary significantly among individuals.
Symptoms
Growth Retardation: Significant growth restriction before and after birth.
Short Stature: Adult height is typically well below average.
Facial Features: Triangular face, prominent forehead, small chin (micrognathia), down-turned corners of the mouth.
Body Asymmetry: Limb length discrepancies (hemihypotrophy), where one side of the body is slightly smaller than the other.
Feeding Difficulties: Poor appetite, gastroesophageal reflux, and difficulty gaining weight during infancy.
Skeletal Abnormalities: Clinodactyly (curved fingers, often the 5th finger), syndactyly (webbed toes).
Other: Increased sweating, hypoglycemia in infancy, delayed motor development, learning difficulties in some cases.
Causes
RSS is primarily caused by epigenetic or genetic alterations affecting genes involved in growth regulation.
Epigenetic Modifications: About 30-50% of cases involve hypomethylation of the imprinting control region 1 (ICR1) on chromosome 11p15.5. This region regulates the expression of the IGF2 (insulin-like growth factor 2) gene.
Maternal uniparental disomy for chromosome 7 (UPD(7)mat): Occurs in approximately 10% of cases. This means the individual inherits both copies of chromosome 7 from the mother instead of one from each parent.
Gene Mutations: Mutations in genes like PLAG1 and *HMGA2* are found in a small percentage of cases.
Unknown Cause: In a significant proportion of individuals with RSS, the underlying genetic or epigenetic cause remains unknown.
Medicine Used
Growth Hormone Therapy: Recombinant human growth hormone (rhGH) is often prescribed to improve growth velocity and final adult height.
Nutritional Support: Special formulas, gastrostomy tube feeding (G-tube) may be necessary to address feeding difficulties and ensure adequate nutrition.
Other Medications: Medications to manage gastroesophageal reflux (GERD) or other specific symptoms may be prescribed as needed.
Is Communicable
Russell-Silver syndrome is not communicable. It is a genetic disorder and cannot be spread from person to person.
Precautions
Since RSS is not communicable, standard precautions for infectious diseases do not apply. However, precautions related to managing the condition include:
Careful monitoring of growth and development.
Nutritional support and management of feeding difficulties.
Early intervention for developmental delays.
Regular medical check-ups to address any complications.
How long does an outbreak last?
Since Russell-Silver syndrome is a genetic condition and not an infectious disease, the concept of an "outbreak" does not apply. The condition is present from birth and is lifelong.
How is it diagnosed?
Diagnosis of RSS is primarily based on clinical findings. There is no single definitive test. Diagnostic criteria include:
Low birth weight and/or length.
Postnatal growth failure.
Typical facial features.
Body asymmetry. Genetic testing and epigenetic analysis (methylation studies of 11p15.5) can help confirm the diagnosis and identify the underlying cause in some cases. Chromosomal microarray may also be used.
Timeline of Symptoms
Prenatal: Intrauterine growth restriction (IUGR) may be detected during pregnancy via ultrasound.
Infancy: Low birth weight, feeding difficulties, hypoglycemia, slow growth.
Childhood: Short stature, distinctive facial features become more apparent, developmental delays may be identified.
Adolescence/Adulthood: Short stature persists, other features remain, potential for learning difficulties. Growth hormone therapy may impact the growth trajectory.
Important Considerations
Variability: The severity of symptoms can vary greatly among individuals with RSS.
Early Intervention: Early diagnosis and intervention (nutritional support, growth hormone therapy, developmental therapies) are crucial for optimizing outcomes.
Multidisciplinary Care: Management requires a multidisciplinary approach involving pediatricians, endocrinologists, geneticists, dietitians, and therapists.
Genetic Counseling: Genetic counseling is recommended for families to understand the inheritance patterns and recurrence risks.