Krabbe Disease, Atypical, Due To Saposin A Deficiency

A number sign (#) is used with this entry because atypical Krabbe disease due to saposin A deficiency is caused by mutation in the prosaposin gene (PSAP; 176801).

Krabbe disease (245200) is a genetically distinct disorder caused by mutation in the galactosylceramidase (galactocerebrosidase) gene (GALC; 606890).

Clinical Features

Spiegel et al. (2005) reported a child, born of consanguineous Arab parents, with saposin A deficiency. She developed normally until age 3.5 months, at which time she showed rapid neurologic deterioration and loss of acquired milestones. At age 6 months, she was almost in a vegetative state without eye contact and with little spontaneous movement. Muscle tone was increased, but reflexes were depressed. Brain imaging showed generalized brain atrophy and diffuse white matter dysmyelination. CSF protein was increased. She died 2 months later of central apnea and respiratory failure. Biochemical studies showed decreased activity of galactocerebrosidase in leukocytes, but normal activity in fibroblasts.

Molecular Genetics

In an infant with saposin A deficiency, Spiegel et al. (2005) identified a homozygous mutation in the PSAP gene (176801.0009).