Prevalence
The worldwide prevalence of this entity is unknown. However, an estimate of 0,5/10000 births in the United Arab Emirates, a population with high frequency of consanguinity, has been estimated.
Main clinical features
Individuals with SWS have distinctive dysmorphic features and progressive congenital skeletal deformities with consequent motor delay. Cognition is normal. Most patients have dysautonomia.
Molecular features
SWS is caused by biallelic loss-of-function variants in the LIFR gene. There are two individuals reported in the literature, harbouring missense variants in both alleles of LIFR, showing a partial SWS phenotype lacking the typical long bone skeletal dysplasia
Inheritance and genetic counselling
SWS is inherited in an autosomal recessive manner. If both parents are heterozygous for a LIFR pathogenic variant, the risk to the offspring of inheriting two LIFR pathogenic variants is 25%.
Management
Treatment is multidisciplinary and symptomatic.