Asparagine Synthetase Deficiency (ASNSD)

Asparagine Synthetase Deficiency (ASNSD)

OMIM number: 615574

Comments closing date: 02/01/2025

Asparagine synthetase deficiency is a rare
hereditary (genetic) condition which impacts the
brain and nervous system. Babies with this
condition are born with a mutation (also called a
pathogenic variant) in both copies of a gene called
ASNS. The ASNS gene makes an enzyme which
helps our body create a cellular building block
called asparagine. If the body cannot make this
amino acid, it leads to significant problems with
the way the brain develops. This causes health
problems like a small, unusually shaped brain,
seizures, severely delayed development, and
problems with feeding and breathing. It can also
cause vision loss and poor muscle tone. The
severity of the symptoms tend to progress with
time. Some babies are born well but experience
regressions in their development, while other
babies are born unwell. Unfortunately, it is very
life-limiting, and babies often die days or months
after birth. There have been other children who
survived to around 7 years of age. There is no
cure for the condition. Each symptom can be
treated on its merits to make them as comfortable
as possible. If both parents carry this condition,
there is a 1 in 4 (25%) chance they could pass it
on each time they conceive a child.

Share information with the HFEA