Haploinsufficiency of WDR26 results in the neurodevelopmental disorder Skraban-Deardorff Syndrome (SKDEAS, OMIM 617616)
Main clinical features
The recognizable phenotype includes intellectual disability/developmental delay, seizures, abnormal gait, and distinctive facial features. Other common features include minor structural brain anomalies, hypotonia, and autistic or repetitive behaviors.
Prevalence
The exact prevalence is unknown, however, based on one study that included 21,400 individuals with intellectual disability who had exome sequencing, 15 individuals were identified with WDR26 mutations. This suggests a frequency of ~1 in 1,500 for individuals with intellectual disability.
Inheritance
All reported cases of SKDEAS have been autosomal dominant. To date, all have been caused by heterozygous de novo mutations. Thus, most affected individuals represent a single occurrence in a family. The recurrence risk for future pregnancies is approximately 1% due to the risk of germline mosaicism in one of the parents. No individuals with WDR26-related intellectual disability have been known to reproduce.