The main clinical features that characterise Weaver syndrome are:
- Increased growth. Individuals with Weaver syndrome are usually tall and /or have a large head circumference (known as macrocephaly). We define growth as being increased if it is greater than two standard deviations above the mean which roughly equates to the 98th centile on the growth charts.
- Intellectual disability. This is variable in Weaver syndrome and ranges from mild through to severe with a mild intellectual disability most frequently reported.
- Characteristic facial appearance. Typically young children with Weaver syndrome have a prominent forehead, small recessed chin and widely spaced eyes. As children grow older, the chin no longer appears recessed. There is considerable overlap in facial appearance between Weaver syndrome and similar condition associated with increased growth called Sotos syndrome.
Other Weaver syndrome clinical associations include (in infancy) fixed flexion of fingers and toes (this is called camptodactyly), umbilical hernia, soft doughy skin and hoarse cry.
Studies are underway to determine whether there is also an increased risk of an embryonal tumour (known as a neuroblastoma) in very early childhood, up to the age of five years.