Overview

KDM5C (also known as JARID1C and SMCX) is an X-linked gene that controls whether many other genes are switched on or off. Research has shown that KDM5C is especially important in early development and impacts how the brain develops.

A variant or 'typo' in the genetic code for KDM5C may occur randomly or may be inherited and is associated with a range of symptoms of which the most common are mild to severe intellectual disability, oral dyspraxia, challenging behaviour and short stature. Symptoms are on a spectrum in terms of occurrence and severity and affect both males and females.

When an individual with a KDM5C variant has clinical symptoms they might be diagnosed by a geneticist with 'KDM5C disorder', 'KDM5C syndrome', 'Claes-Jensen syndrome' or 'MRXSJ'.

A KDM5C variant is identified through genetic sequencing which has only started to become widely accessible in recent years. This means there are likely to be many undiagnosed adults and children living with the condition. The incidence of KDM5C disorder is difficult to gauge, however, to date over 730 individuals from across the globe have joined the the KDM5C Support Group Facebook group and new families continue to join each week.

Further Reading

What researchers know about KDM5C
Symptoms
Practical advice for carers including medical interventions / therapies and education
KDM5C presentations from Rare Disease Day 2020
An introduction to Genetics
KARES Foundation