Males and CASK
LOF variants
Boys with a genetic variant that cause a loss of function of the CASK gene are sadly lost during pregnancy or only survive for a few months after birth.
These boys usually have MICPCH, severe intractable epilepsy with severe to profound developmental delay or no development. Some boys however do not have the genetic change in all of their cells, this is known as mosaicism and means that boys can survive.
These boys have MICPCH, severe epilepsy and developmental delay with ID, similar to the symptoms and features seen in girls.
Hypomorphic variants
Boys who have a genetic change to their only copy of the CASK gene that causes it to have a reduced function are likely to survive and can have a broad spectrum of symptoms and features.
These involve a range of severities from mild ID to severe ID and MICPCH with or without eye anomalies, such as involuntary eye movement (nystagmus), and seizures.
They may also have other clinical features such as severe weak muscle tone (hypotonia).[1]