NORD gratefully acknowledges Dr. Irène Netchine, Laboratoire d'Explorations Fonctionnelles Endocriniennes, Paris, France, and Jennifer Salem, The MAGIC Foundation, for assistance in the preparation of this report.
Russell-Silver syndrome (RSS) is a rare disorder characterized by intrauterine growth retardation and postnatal growth deficiency along with a handful of common physical characteristics and a range of other symptoms. The wide spectrum of phenotype findings vary both in incidence rate and severity from one individual to another. Besides prenatal and postnatal growth retardation, the most common characteristics are normal head circumference (appearing large for the body), a large forehead that protrudes out from the plane of the face, a triangular-shaped face, a pinky that is fixed or "locked" in a bent position (clinodactyly), lack of appetite/low BMI, and undergrowth of one side or limb(s) of the body (hemihypotrophy), resulting in unequal (asymmetric) growth. The majority of children with RSS fall within the normal range of intelligence, but are more likely to have motor and speech delays. Intervention at an early age (infancy) is critical. Some evidence indicates that there may be neurodevelopmental differences between the different genetic causes of RSS. RSS is genetically heterogeneous, meaning that different genetic abnormalities are believed to cause the disorder. Abnormalities affecting certain genes on chromosomes 7 or 11 have been found in up to 60% of RSS patients, leaving approximately 40% of patients where the underlying cause of RSS is not known.
This syndrome was independently identified by H.K. Silver in 1953 and A. Russell in 1954. In the early medical literature, the term Silver syndrome had been used to denote a child with low birth weight, overgrowth of one side (in fact, undergrowth) of the body (lateral asymmetry), and clinodactyly, whereas the term Russell syndrome had been used to denote a similar condition without asymmetry. However, most researchers now consider Russell-Silver syndrome one disease entity. The disorder is usually called Russell-Silver syndrome in the United States and Silver-Russell syndrome in Europe
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