Question

Hunter syndrome is a rare, inherited disorder where sugar molecules are not properly broken down over time and build up in organs and tissues in the body. Symptoms often begin between 2 and 4 years old, gradually worsen over time, and include skeletal irregularities, enlarged internal organs, stunted growth, and developmental delays. Patients have a deficiency of a specific sulfatase enzyme activity, iduronate 2 -sulfatase. The enzyme is responsible for breaking down a specific type of polysaccharide, glycosaminoglycan, which then accumulates in a specific organelle in cells. Where would most glycosaminoglycans accumulate in patients deficient in iduronate 2 -sulfatase?

Answer 1

In Hunter syndrome, a deficiency in iduronate 2-sulfatase enzyme leads to the accumulation of glycosaminoglycans in the lysosomes, resulting in various symptoms including organ enlargement and developmental delays. This accumulation due to enzyme deficiency is characteristic of mucopolysaccharidoses like Hunter syndrome.

Step-by-step explanation:

Hunter syndrome is a genetic disorder that falls into a group of diseases known as mucopolysaccharidoses (MPS), specifically MPS II. It is characterized by an enzyme deficiency; specifically, the enzyme iduronate 2-sulfatase. This enzyme is crucial for breaking down glycosaminoglycans (GAGs) like heparan sulfate and dermatan sulfate, which are found in the extracellular matrix and cellular surfaces. Without proper breakdown, GAGs accumulate within the lysosomes, which are the organelles responsible for degrading various kinds of biomolecules. As a result, the lysosomes swell and disrupt the normal function of cells, leading to the varied symptoms of Hunter syndrome such as skeletal deformities, enlarged organs, and developmental delays.

Other examples of diseases due to enzyme deficiencies include Hurler syndrome and Sanfilippo syndrome, where similar accumulations of GAGs occur. Disorders like Gaucher's and Tay-Sachs disease also involve lysosomal storage but with different substrates. This reflects the overarching concept that lysosomes are integral to cellular waste management; when their function is impaired by enzyme deficiencies, the consequences can be severe and systemic.

Understanding the cellular mechanics of Hunter syndrome and related disorders underscores the importance of enzymes in human health and the complicated nature of genetic diseases. It also highlights the vital role of lysosomes in cells and the devastating effects that can arise when they are unable to carry out their normal functions due to enzyme deficiencies.