What is Russell-Silver syndrome?
Russell-Silver syndrome, also known as Silver-Russell syndrome, is a rare growth disorder estimated to affect between 1 in 30,000 to 1 in 100,000 people.
The cause of Russell-Silver syndrome is genetic and involves genes that control growth. Babies with Russell-Silver syndrome often have a lower-than-average birth weight and length and struggle to feed and grow at a normal rate. Adults with Russell-Silver syndrome are typically shorter than average. Other aspects of growth are affected; people with Russell-Silver syndrome may have different limb lengths and a large head in relation to the size of the rest of their body.
The symptoms of Russell-Silver syndrome can look different from person to person and the associated challenges change from infancy to adulthood. Getting diagnosed early is key to ensuring your child receives the right treatment as they age so they can fulfil their full potential.
Hear advice from other parents whose children are also short in stature, compared with others their age. https://morethanheight.com/en/life-with-growth-disorders/advice-for-early-years-parents-of-a-baby-or-toddler-with-a-growth-disorder/
What causes Russell-Silver syndrome?
There are two main genetic abnormalities known to cause Russell-Silver syndrome, on either chromosome 7 or chromosome 11.
Chromosomes store genetic information. Most people have 46 chromosomes organised in 23 pairs. One chromosome in each pair comes from the mother, and the other from the father. Both contain the same genes, meaning a person will have two copies of all their genes.
Genes are made up of DNA. For most genes, both copies will be “turned on” and considered active. Genes are commonly “turned off” and considered inactive by a process called DNA methylation. For some genes, one copy is “turned off” and considered inactive and only one copy is “on” or active. The parent the copy is from dictates whether the gene is “on” or “off”. This is called genetic imprinting.
Genetic imprinting is important for normal development. You may hear Russell-Silver syndrome referred to as an imprinting disorder.
In around 30–60% of people with Russell-Silver syndrome the DNA methylation which “turns off” one of the copies of a group of genes on chromosome 11 has gone wrong.4 This is called loss of methylation on chromosome 11p15.
About 5–10% of people with Russell-Silver syndrome have mistakenly inherited two copies of chromosome 7 from their mother, rather than one from each parent. This is called maternal uniparental disomy.
Rarely, Russell-Silver syndrome can be caused by mutations in a series of genes on chromosome 11: CDKNIC, IGF2, PLAG1 and HMGA2. It is thought that these mutations are associated with the few cases of parents who have multiple children with Russell-Silver syndrome.
What are the symptoms of Russell-Silver syndrome?
The symptoms of Russell-Silver syndrome can vary widely between different people. Symptoms include:
- Large head in relation to body size
- Prominent forehead
- Triangular face shape (broad forehead that narrows towards the chin)
- Dental overcrowding and overbite
- Downturned corners of the mouth
- High-pitched or squeaky voice
- Low-set ears that are rotated back
- Different length arms and/or legs (limb asymmetry)
- Curved little finger
- Short stature
- Excessive sweating
- Low muscle mass
Russell-Silver syndrome is associated with poor growth before and after birth. Babies struggle to feed, have poor appetite and often have stomach problems; this leads them to not being able to put on as much weight as others their age.
As children age, they grow at a slower rate because they aren’t consuming enough calories to support normal growth. Children with Russell-Silver syndrome commonly weigh less than others their height because they have low muscle mass. Puberty commonly starts earlier and the associated growth spurt is weaker.
If your child is short in stature, keeping track of their growth can help identify if there is a problem early on. Compare your child’s measurements to the national average to see if they are within a healthy range.
Calculate your child’s growth
It is important to keep track of your child’s growth in order to identify if there is a problem early on. We recommend measuring your child every 6 months, which is now easier, with our simple to use growth calculator.
What complications are associated with Russell-Silver syndrome?
Complications associated with Russell-Silver syndrome include:
- Digestive problems including persistent vomiting and constipation
- Coronary heart disease (CHD)
- High blood pressure
- Delayed development of motor skills
- Speech issues
- Scoliosis (a spine with a sideways curve)
- Type 2 diabetes
- Recurrent episodes of dangerously low blood sugar, especially at night (hypoglycaemia)
- Dental issues
- Breathing issues during sleep
How is Russell-Silver syndrome diagnosed?
While a doctor will base a diagnose Russell-Silver syndrome primarily on the presence of certain characteristics, it can be difficult due to the wide variety and severity of the symptoms of Russell- Silver syndrome and their similarity with other growth disorders. Therefore, it is thought that a lot of people living with Russell-Silver syndrome are misdiagnosed or remain undiagnosed.
If your doctor suspects your child has Russell-Silver syndrome they will likely perform genetic testing, which also tells you the subtype. The type of genetic testing is called DNA methylation analysis.
However, if the genetic test is negative for Russell-Silver syndrome, it does not rule out your child having Russell-Silver syndrome. Only 60% of people who have been diagnosed with Russell-Silver syndrome have a positive test confirming the underlying molecular cause.
It is important you speak to your doctor if you have any concerns about your child’s height. Use this helpful guide on what questions to ask, and what to expect from your visit. https://morethanheight.com/en/talk-to-your-doctor/visiting-your-paediatrician/
What is the life expectancy of someone with Russell-Silver syndrome?
There is no evidence that Russell-Silver syndrome reduces life expectancy.
Is Russell-Silver syndrome inherited?
Most cases of Russell-Silver syndrome are thought not to run in the family. Parents of a child with Russell-Silver syndrome are unlikely to have another child with the condition. It is also unlikely for people with Russell-Silver syndrome to have a child who also has the condition.
There are some rare cases of Russell-Silver syndrome where multiple children in the same family have been affected. It is recommended you speak to a genetic counsellor about any concerns.