Russell Silver Syndrome (RSS) Intrauterine Growth Retardation (IUGR) Small for Gestational Age (SGA)
Russell Silver Syndrome is very rare; it is very difficult to put a number on this but estimates are in the region of 1 in 50,000 births, and little is known about what causes it. In most families, only one child has the condition, but very occasionally more than one affected child is born into the same family. This may suggest a genetic basis for this condition, and a lot of research is being done in this area. A genetic irregularity has been found in some children with milder forms of IUGR.
Intrauterine Growth Retardation
A low birth weight means one which is inappropriately low given the length of the pregnancy - for a baby born at term this would be less than 2.5kg. The inappropriately low weight indicates that the growth of the baby in the womb has been unsatisfactory – hence the name Intrauterine Growth Retardation.
Most babies born too small for their gestational age catch up over the first two or three years of life. However, in about a third, complete catch-up growth does not occur. These children remain small and don’t reach their genetic potential as defined by their parental heights.
The diagnosis of IUGR is based on comparison of the babies’ weight centile at birth, with standards including the baby’s gestational age. Ideally, infant length should also be taken into account.
Russell Silver Syndrome (RSS)
The diagnosis of RSS is based on that of IUGR. Some of the following symptoms may also be present:
- Feeding problems - early feeding problems are common. The baby is often reluctant to feed, and eats little and with difficulty
- Sweating - the babies sweat a lot, especially at night, and have a grey or pale skin. In some infants, this is a sign of low blood sugar (hypoglycaemia). As they get older, these infants or children may have altered behaviour, such as hyperactivity or, conversely, tiredness, as a symptom of their low blood sugar levels
- Face - the face is triangular with a small jaw and a pointed chin. The mouth tends to curve downwards
- Eyes - a blue tinge to the whites of the eyes in younger children
- Head - the head circumference may be a normal size, which means it can seem disproportionately large compared to a small body
- Fontanelle - the opening between the bones of the skull, the fontanella, may be very wide and late to close in babies
- Clinodactaly - the little finger on each hand may be small and curve inwards.
- Body asymmetry - one side of the body grows more slowly than the other
- Continued poor growth - with no catch up into the normal centile lines on the growth chart
- Puberty - may begin early
Typical growth and weight chart for a boy with Russell Silver Syndrome
The term IUGR probably represents a spectrum of conditions (some of which are described as Russell Silver syndrome) resulting from abnormal foetal growth. As with any syndrome, not every child will have all the features described. The child who has IUGR, but has not experienced catch-up growth during their first year, will remain small for their age and probably very thin. Their final height may be in the region of 157cm (5'2") for a boy and 144cm (4'9") for a girl.
Many features of IUGR may require medical help and support, so discuss any concerns with your growth specialist, who can then refer your child to another appropriate specialist if necessary. This may be especially relevant when considering leg asymmetry and the referral to an orthopaedic surgeon with experience in the procedure of limb lengthening (not shortening).
There is no definitive way to help your child put on weight, although this can be very worrying. These children are healthy and active, and confrontation over food should be avoided where possible.
GH has been shown to be beneficial both in the short term, and the long-term, with final height increased by up at 14cm. As a result GH is now licensed after 4 years of age for children born SGA who fail to show catch-up growth and who are short both compared to the normal population and their parents.
To NICE and Beyond: What's new with GH? (PDF)
NICE recommends somatropin to treat growth failure in children (PDF)
Emergency Treatment for Children
with Cortisol and GH Deficiencies
and those Experiencing
including Russell Sliver