Silver-Russell dwarfism, also called Silver-Russell syndrome (SRS) or Russell-Silver syndrome (RSS) is a growth disorder occurring in approximately 1/50,000 to 1/100,000 births. In the United States it is usually referred to as Russell-Silver Syndrome, and Silver-Russell Syndrome elsewhere. It is one of 200 types of dwarfism

Dwarfism

Dwarfism is short stature resulting from a medical condition. It is sometimes defined as an adult height of less than 4 feet 10 inches  , although this definition is problematic because short stature in itself is not a disorder....

 and one of five types of primordial dwarfism

Primordial Dwarfism

Primordial dwarfism is a form of dwarfism that results in a smaller body size in all stages of life beginning from before birth. More specifically, primordial dwarfism is a diagnostic category including specific types of profoundly proportionate dwarfism, in which individuals are extremely small...

 and is one of the few forms that is considered treatable in some cases.

There is no statistical significance of the syndrome occurring in males or females.

Etiology

Its exact cause is unknown, but present research points toward a genetic component, possibly following maternal genes.

It involves hypomethylation of H19

H19 (gene)

H19 is a gene for a long noncoding RNA, found in humans and elsewhere. This gene seems to have a role in some forms of cancer.The H19 gene is also known as ASM, ASM1 and BWS, among others....

and IGF2.

Diagnosis

Although confirmation of a specific genetic marker is in a significant number of individuals, there are no tests to clearly determine if this is what a person has.
The syndrome is usually caused by a maternal uniparental disomy

Uniparental disomy

Uniparental disomy occurs when a person receives two copies of a chromosome, or part of a chromosome, from one parent and no copies from the other parent.. UPD could involve isodisomy or heterodisomy ....

 (UPD) on chromosome 7, in 10% of the cases, which is an imprinting error where the person receives two copies of chromosome 7 from the mother (maternally inherited).
As a 'syndrome' a diagnosis is typically given for children upon confirmation of the presence of several 'symptoms' listed below.

Symptoms are Intrauterine Growth Restriction

Intrauterine growth restriction

Intrauterine growth restriction refers to poor growth of a baby while in the mother's womb during pregnancy. The causes can be many, but most often involve poor maternal nutrition or lack of adequate oxygen supply to the fetus....

 (IUGR) combined with some of the following:

• Often small for gestational age (SGA) at birth (birth weight less than 2.8kg)
• Feeding problems: the baby is uninterested in feeding and takes only small amounts with difficulty
• Hypoglycemia
  Hypoglycemia
  Hypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...
  
  
• Excessive sweating as a baby, especially at night, and a greyness or pallor of the skin. This may be a symptom of hypoglycemia
• Triangular shaped face with a small jaw and a pointed chin that tends to lessen slightly with age. The mouth tends to curve down
• A blue tinge to the whites of the eyes in younger children
• Head circumference may be of normal size and disproportionate to a small body size
• Wide and late-closing fontanelle
  Fontanelle
  A fontanelle is an anatomical feature on an infant's skull.-Anatomy:Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull causes the...
  
  
• Clinodactyly
  Clinodactyly
  -References:...
  
  
• Body asymmetry: one side of the body grows more slowly than the other
• Continued poor growth with no "catch up
  Compensatory growth (organism)
  Compensatory growth, also known as catch-up growth and compensatory gain, is an accelerated growth of an organism following a period of slowed growth, particularly as a result of nutrient deprivation. Oftentimes, the body weights of animals who experience nutritional restriction will over time...
  
  " into the normal centile lines on growth chart
• Precocious puberty
  Precocious puberty
  As a medical term, precocious puberty describes puberty occurring at an unusually early age. In most of these children, the process is normal in every respect except the unusually early age, and simply represents a variation of normal development. In a minority of children, the early development is...
  
   (occasionally)
• Low muscle tone
• Gastroesophageal reflux disease
  Gastroesophageal reflux disease
  Gastroesophageal reflux disease , gastro-oesophageal reflux disease , gastric reflux disease, or acid reflux disease is chronic symptoms or mucosal damage caused by stomach acid coming up from the stomach into the esophagus...
  
  
• A striking lack of subcutaneous fat
• Late closing of the opening between the heart hemispheres
• Constipation (sometimes severe)

Treatment

The caloric intake of children with RSS must be carefully controlled in order to provide the best opportunity for growth, if the child is unable to tolerate oral feeding then enteral feeding may be used, such as the percutaneous endoscopic gastrostomy

Percutaneous endoscopic gastrostomy

Percutaneous endoscopic gastrostomy is an endoscopic medical procedure in which a tube is passed into a patient's stomach through the abdominal wall, most commonly to provide a means of feeding when oral intake is not adequate. The procedure is an alternative to surgical gastrostomy insertion, and...

.

In children with limb-length differences or scoliosis

Scoliosis

Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...

, physiotherapy can alleviate the problems caused by these symptoms. In more severe cases, surgery to lengthen limbs may be required. To prevent aggravating posture difficulties children with leg length differences may require a raise in their shoe.

Growth hormone therapy is often prescribed as part of the treatment of RSS. The hormones are given by injection typically daily from the age of 2 years old through teenage years. It may be effective even when the patient does not have a Growth Hormone deficiency. Growth Hormone therapy has been shown to increase the rate of growth in patients and consequently prompts 'catch up' growth. This may enable the child to begin their education at a normal height, improving their self-esteem and interaction with other children. The effect of growth hormone therapy on mature and final height is as yet uncertain. There are some theories suggesting that the therapy also assists with muscular development and managing hypoglycemia

Hypoglycemia

Hypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...

.

External links

• http://www.magicfoundation.org
• http://www.childgrowthfoundation.org
• Russell-Silver Support.Org
• GeneReviews/NCBI/NIH/UW entry on Russell-Silver Syndrome
• Russell-Silver Syndrome Support - www.rss-support.nl
• http://www.facebook.com/groups/rss.people/#!/groups/rss.people/ (TARSS, Group for teens and adults with Russell Silver Syndrome)