De novo mutations in the SETBP1 gene are associated with learning problems or intellectual disability and a decrease in expressive language. These de novo mutations cause SETBP1 haploinsufficiency. This disorder is completely different compared to SGS and individuals with this disorder don’t show an increased risk to develop similar symptoms. This disorder is caused by a de novo mutation in the SETBP1 gene and occurs in people with no history of a similar disorder in the family. The exact prevalence of SETBP1 disorder is currently still unknown. Only a few reports on individuals with this disorder have been published in medical literature. More information about novel individuals with a SETBP1 mutation will be needed to establish reliable information about clinical findings and prevalence.
Haploinsufficiency of SETBP1 leads to expressive speech impairment and mild-moderate developmental delay. Previously reported individuals show an apparent discrepancy between expressive and receptive language skills. A complete lack of expressive speech and intact receptive language abilities have been noted in a few individuals. These individuals were able to communicate using gestures and mimic expression of face and body with surprising efficacy. Other features included decreased fine motor skills, subtle facial features, hyperactivity and autistic traits.