CLPB deficiency

CLPB deficiency is a rare disorder characterized by neurological problems and a shortage of infection-fighting white blood cells (neutropenia). Signs and symptoms of the condition develop by early childhood, and their severity varies widely among affected individuals.

In the most severely affected individuals, features of CLPB deficiency are apparent in infancy and sometimes at birth. Affected babies have serious neurological problems, which can include an exaggerated startle reaction (hyperekplexia) to unexpected stimuli such as loud noises, reduced movement, muscle tone that is either decreased (hypotonia) or increased (hypertonia), swallowing problems, difficulty breathing, and recurrent seizures (epilepsy). These babies may also have movement abnormalities, such as difficulty coordinating movements (ataxia), involuntary tensing of the muscles (dystonia), or uncontrolled movements of the body (dyskinesia). In addition, these babies have recurrent, life-threatening infections due to severe neutropenia. Affected individuals are at risk of developing a blood cell disorder called myelodysplastic syndrome or a form of blood cancer called leukemia. Because of their severe health problems, affected infants usually live only a few weeks or months.

Moderately affected individuals have neurological problems similar to those described above, although they are less severe. They include hypotonia, muscle stiffness (spasticity), and movement abnormalities. Other features of moderate CLPB deficiency include epilepsy and mild to severe intellectual disability. Neutropenia in these individuals can lead to recurrent infections, although they are not life-threatening.

Mildly affected individuals have no neurological problems, and although they have neutropenia, it does not increase the risk of infections. Some people with mild CLPB deficiency develop deposits of calcium in the kidneys (nephrocalcinosis) or kidney (renal) cysts.

Many people with mild, moderate, or severe CLPB deficiency have clouding of the lenses of the eyes (cataracts) from birth (congenital) or beginning in infancy.

CLPB deficiency is associated with increased levels of a substance called 3-methylglutaconic acid in the urine (3-methylglutaconic aciduria). This abnormality, which provides a clue to the diagnosis, does not appear to cause any health problems.