Gm1 And Gm2 Gangliosidoses

3.2.1. Clinical Features

GM1 gangliosidosis is a rare lysosomal storage disorder that occurs as a result of deficiency of the lysosomal enzyme 0-galactosidase. The clinical presentation reflects the underlying severity in pathology. If there is severe accumulation, the disease presents in infancy (pseudo-Hurler's); moderate accumulation presents in early childhood or focal accumulation presents in young adulthood (9). GM2 gangliosidosis is the

Fig. 1. MLD, juvenile form. Shown is a 14-yr-old female with characteristic involvement of the frontal white matter in the late onset or juvenile form. In (A and B) note the partial preservation of the subcortical U fibers. Axial T2 and FLAIR images demonstrate increased signal intensity within the periventricular white matter (frontal white matter more severely affected than the parietal. (Courtesy of Dr. Gary L. Hedlund, Salt Lake City, UT.)

Fig. 1. MLD, juvenile form. Shown is a 14-yr-old female with characteristic involvement of the frontal white matter in the late onset or juvenile form. In (A and B) note the partial preservation of the subcortical U fibers. Axial T2 and FLAIR images demonstrate increased signal intensity within the periventricular white matter (frontal white matter more severely affected than the parietal. (Courtesy of Dr. Gary L. Hedlund, Salt Lake City, UT.)

Fig. 2. MLD, late-infantile form. Shown is a 2-yr-old female with characteristic involvement of the posterior white matter. Axial FLAIR image demonstrates predominant high signal intensity within the posterior periventricular white matter with (dorsofrontal) progression to involve the frontal white matter.

Fig. 2. MLD, late-infantile form. Shown is a 2-yr-old female with characteristic involvement of the posterior white matter. Axial FLAIR image demonstrates predominant high signal intensity within the posterior periventricular white matter with (dorsofrontal) progression to involve the frontal white matter.

general term for two autosomal-recessive lysosomal storage disorders, Tay Sachs disease and Sandhoff disease, which are both characterized by the accumulation of lipids, GM2 gan-gliosides, primarily in the central nervous system. GM2 gangliosidosis occurs secondary to a deficiency of hexosaminidase A activity. Tay Sachs is a form mainly found in Ashkenazi Jews and is caused by a deficiency in the B-N-acetyl hexosaminidase^ isozyme. Sandhoff disease (deficiency of A and B isozymes of hexosaminidase) has a clinical course similar to Tay Sachs but also has visceral involvement (9). There are three clinical variants of the disease based on age of onset: infancy (type I), age 2-6 yr (type II), and adulthood (type III); the earlier the age of onset, the more severe the disease. This presumably reflects the underlying severity of pathology. Late-onset GM2 gangliosidosis occurs during childhood or adolescence and is characterized by poor coordination, tremor, and/ or slurred speech. With advancing age, patients develop neurologic symptoms, including ataxia (inability to coordinate voluntary muscle movement), unsteady gait, muscle weakness, and slurred speech. In the fourth decade of life, mental and behavioral involvement may become evident (22).

3.2.2. MRI Findings in GM1 and GM2 Gangliosidosis

The MRI findings in GM1 gangliosidosis differ depending on the age of presentation and thereby reflect the extent of underlying ganglioside accumulation. If the disease presents in infancy, there is extensive demyelination and gliosis in the white matter that will appear as diffuse high signal intensity on the T2-weighted images on MRI. In the childhood form, diffuse generalized cerebral and cerebellar atrophy has been described.

0 0

Post a comment