Weaver syndrome is an overgrowth disorder that begins prenatally and is characterized by an accelerated bone development.
Other symptoms of this disorder include reduced muscle tone with exaggerated reflexes, a slow development of voluntary movement, psychomotor retardation, distinct physical features, and limb defects. Babies with Weaver syndrome have a hoarse, low-pitched cry.
The disorder was first described by Doctor David Weaver in 1974. The different symptoms are a result of an accelerated prenatal growth, that continues postnatally during infancy. In addition, this disorder is linked to accelerated bone development, and accelerated maturation, especially in the face.
Who is at risk?
Weaver syndrome is a rare condition that affects males three times more often than females. Around 30-50 cases of this disorder have been described in medical literature.
Weaver syndrome mostly occurs sporadically, which means that children who develop this condition do not inherit it from their parents. An autosomal inheritance pattern has been reported in very few cases, where both parent and child are affected by the condition. The cause for this disorder is unknown and the genes involved have yet to be identified.
The disorder is usually caused by a mutation in the gene EZH2, that provides instructions for the production of an enzyme called histone, this enzyme modifies proteins known as histones, which are structural proteins that attach to the DNA and give the chromosomes their form.
Adding a molecule known as methyl to the histones can shut down the function of certain genes and obstruct vital development processes. It remains unclear how mutations in the EZH2 gene cause the typical symptoms that are characteristic of Weaver syndrome.
The main differential diagnosis is Sotos syndrome, which has considerate overlap with Weaver syndrome. Other disorders that should be considered include Beckwith-Wiedemann syndrome, Simpson-Golabi syndrome, Malan overgrowth syndrome, and Marfan syndrome.
Prenatal diagnosis should be undergone in high-risk pregnancies.
Treatment of Weaver syndrome focuses on supportive treatment of symptoms. Genetic counselling is available to people with this disorder and their families. In addition, orthopedic treatment and surgery can help correct limb deformities. With the right support and treatment, people with Weaver syndrome can lead normal lives.