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Russell Silver Syndrome (RSS) is a genetic disorder that was first described by Silver and colleagues in 1953 and then by Russell in 1954. It is a syndrome that occurs at birth and involves poor growth, low birth weight, short-height and growth retardation. The disorder is difficult to diagnose in older children and adults as compared to infants and young children. Both men and women are equally susceptible to the syndrome.
One of the important aspects of the Russell Silver syndrome is its variant phenotype. A phenotype in this context is the physical characteristics and abnormalities present in an individual patient suffering from Russell Silver syndrome. Some individuals with this syndrome show many traits and therefore, a severe phenotype, while others show mild traits as well.
RSS was not always thought to be a genetic disorder because it rarely recurred within a family. However, the recent research findings of genetic mechanisms have confirmed that RSS is a genetic disorder. Scientists believe that the RSS phenotype is linked with multiple genotypes. A genotype is considered as the status of a particular gene at a particular location on a particular chromosome. In case of abnormal genotype, some genetic alteration takes place such as duplication, deletion, substitution or other errors within the code of a specific gene.
Abnormal genotypes result in abnormal phenotypes, and that’s the reason why a marked phenotypic variability within the group of patients is found. But it is very difficult to decide which child is suffering from Russell Silver syndrome. It has been estimated that 7 to 10 percent of patients with this disorder have a defect in a gene, which is called the maternal uniparental disomy (UPD) for chromosome 7.
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The diagnosis of the Russell Silver syndrome is not an easy task, as the symptoms are related to many other diseases as well. However, patients show at least four of the following features:
- Low birth weight
- Classic facial phenotype
- Developmental delay
- Poor head
- Poor postnatal growth
- Birth weight less than or equal to 2 standard deviations (SD)
- Clinodactyly of the 5th finger
Chromosomal analysis and karyotyping is used to evaluate for the disorder in patients suspected with Russell Silver syndrome.If the disorder is suspected then patient and parental blood is obtained for evaluating uniparental disomy (UPD) of chromosome7. This test is done in a specialized molecular-biology diagnostic laboratory.
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Growth hormone therapy must be undertaken in a child with Russell Silver syndrome, especially for those who have not manifested sufficient catch-up growth by age two years. Growth hormone has been approved in the United States in 2001 by the US Food and Drug Administration for use in children born small.
Genetic counseling must be done in order to get the right information about the syndrome and get the right treatment.
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(web): Silver Russell syndrome -- http://emedicine.medscape.com/article/948786-overview
(Web): INTRODUCTION Russell-Silver Syndrome -- http://www.magicfoundation.org/www/docs/112.111/russell_silver_syndrome