Professionals

Prevalence
Occurrence of the SLC9A7-related variant (p.L515F) is very rare. It has been reported in two unrelated families with multigenerational non-syndromic intellectual disability.

Clinical characteristics
Male individuals with the SLC9A7-related variant (p.L515F) are characterized by moderate to severe intellectual disability, motor and speech delay, hypotonia (decreased muscle tone), proximal muscle weakness, variable deep tendon reflexes, and bilateral clinodactyly.

Inheritance
Since the SLC9A7gene is located on the X chromosome (position Xp11.3), SLC9A7-related conditions are known as X-linked conditions. As males have only one X chromosome, those possessing the defective variant SLC9A7p.L515F are invariably affected. Females who are genetic carriers of the condition will have one X chromosome with a SLC9A7variant, while the other X chromosome will contain a functional copy of the gene. Hence, female carriers may not show any signs or symptoms of the condition. When a female who is carrying the defective variant SLC9A7p.L515F variant has children and the variant is passed on to her children, then a male child will have a SLC9A7-related condition.