GM1-gangliosidosis (adult onset)
General description
GM1-gangliosidosis is an autosomal recessive disorder caused by a deficiency of β-Galactosidase. This enzyme deficiency affects the nervous system and internal organs in GM1-gangliosidosis, whereas it affects skeletal muscles in Morquio disease. In GM1-gangliosidosis, gangliosides accumulate in various tissues such as the brain, liver, spleen, and kidneys due to the lack of β-Galactosidase.
GM1-gangliosidosis is classified into infantile, juvenile, and adult forms. Symptom onset in adult form typically occurs between early childhood and late adolescence, with diagnosis often delayed until adulthood due to phenotypic variability. The adult form presents with normal initial development and mild intellectual impairment but starts with gait disturbances and speech difficulties before age 10. Almost all adult cases involve dystonia, particularly in the facial muscles, which is an important diagnostic feature.
References
- Muthane, Uday, et al. "Clinical features of adult GM1 gangliosidosis: report of three Indian patients and review of 40 cases." Movement disorders: official journal of the Movement Disorder Society 19.11 (2004): 1334-1341.
Putaminal lesion
T2-weighted MRI consistently demonstrates bilateral symmetric hyperintensities in the posterior putamen
Globus pallidus
Gradient-echo sequences reveal hypointense signals in the globus pallidus, reflecting iron deposition secondary to chronic neuroinflammation. The "wishbone sign"—a distinctive pattern of T2 hypointensity extending from the globus pallidus to the substantia nigra—is observed in advanced cases.