Autosomal recessive
Caused by changes in both copies of DHCR24, which makes the enzyme that performs the final step converting desmosterol into cholesterol. Desmosterol accumulates and cholesterol may be reduced.
Signs and symptoms
Developmental delay, with delayed speech and motor skills, is typical. Brain differences are common, such as a malformed corpus callosum (the band joining the two halves of the brain) and loss of white matter. Muscle stiffness (spasticity) and stiff, rigid joints (arthrogryposis) are commonly seen. Other features in some people include short stature, an unusually small or large head, a small lower jaw, cleft palate, eye movement problems, heart defects and seizures.
What a diagnosis changes
Diagnosis is confirmed by measuring sterols in blood. No specific treatment is described, and care is supportive, with developmental support, physiotherapy and seizure treatment. Genetic counselling explains the recessive inheritance, and carrier testing is available for relatives.
Genes analysed
