Which clinical feature can be observed in Niemann-Pick disease, but not in Tay-Sachs disease?

Niemann-Pick disease and Tay-Sachs disease are both lysosomal storage disorders, but they present with distinct clinical features due to the different enzymes that are affected.

In Niemann-Pick disease, particularly the type associated with sphingomyelinase deficiency, a prominent clinical feature is areflexia, which refers to the absence of reflexes. This occurs due to the degeneration of neurons, particularly in the spinal cord and peripheral nerves. The involvement of the central and peripheral nervous systems leads to various symptoms, including hypotonia, feeding difficulties, and developmental regression, but the absence of reflexes is a key distinguishing feature when comparing it to Tay-Sachs disease.

On the other hand, Tay-Sachs disease, which is caused by a deficiency in hexosaminidase A, is marked by a characteristic cherry-red spot on the macula, hypotonia, and progressive neurodegeneration, but it does not typically present with areflexia. Instead, the symptoms of Tay-Sachs evolve through stages of developmental regression, leading to loss of voluntary skills, but reflexes may still be preserved until later stages of the disease.

Therefore, the presence of areflexia in Niemann-Pick disease is a distinctive feature that can help differentiate it