Mannosidosis, Beta A, Lysosomal (MANSB)

Mannosidosis, Beta A, Lysosomal (MANSB)

OMIM number: 248510

Comments closing date: 12/08/2024

Beta-mannosidosis is a rare autosomal recessive metabolic condition, caused by mutations in the MANBA gene on chromosome 4. This inborn error of metabolism falls into the category of lysosomal storage disorders. The MANBA gene codes for an enzyme that breaks down certain types of sugar molecules. Failure to break down these molecules, leads to a build-up of these sugar molecules in the lysosomes (the recycling machines of the cell) and this damages the cells, and causes the symptoms of the condition. Those affected with the condition are typically affected with developmental delay and intellectual disabilities, and sometimes seizures. Behavioural problems (eg. hyperactivity, impulsivity, aggression) are common and affected individuals may also be introverted and prone to depression. Sensorineural hearing loss and speech impairment are also a feature. There are wide ranging additional health issues including: increased occurrence of infections; swallowing difficulties; poor muscle tone (hypotonia), and reduced sensation or other nervous system abnormalities in the extremities (peripheral neuropathy). They may also exhibit distinctive facial features, and clusters of enlarged blood vessels forming small, dark red spots on the skin (angiokeratomas). The rarity of this condition means that the number of reported cases worldwide is still in double figures.

Share information with the HFEA