SNP Shot: Genomic Insights

Laryngo-onycho-cutaneous (LOC) syndrome is a rare condition characterized by abnormalities affecting the larynx (voicebox), nails (fingernails and toenails), and skin. A key feature of this disorder is the abnormal growth of granulation tissue in various parts of the body. Granulation tissue, a red and bumpy tissue, is a natural part of wound healing, normally replaced by skin cells as the wound closes. However, in individuals with LOC syndrome, this tissue proliferates excessively even without significant injury.

Infants with LOC syndrome often present with a hoarse cry, a consequence of ulcers or excessive granulation tissue formation in the larynx. This excess tissue can obstruct the airways, leading to severe and potentially fatal breathing difficulties, often resulting in early mortality.

In addition to the larynx, granulation tissue also affects the eyes in LOC syndrome, specifically the conjunctiva (the moist membrane lining the eyelids and the white of the eye). This abnormal tissue growth frequently causes impaired vision or complete blindness.

Other common characteristics of LOC syndrome include cutaneous erosions, which are areas of missing skin. These erosions heal slowly, are prone to infection, and can cause significant discomfort. Affected individuals may also exhibit malformed nails and small, abnormal teeth. The enamel, the hard outer layer of teeth, is thin in these individuals, predisposing them to frequent dental cavities.

LOC syndrome is generally classified as a variant of junctional epidermolysis bullosa, a condition marked by extremely fragile skin that blisters easily. While individuals with junctional epidermolysis bullosa may share some features with LOC syndrome, they typically do not exhibit the overgrowth of granulation tissue in the conjunctiva that is characteristic of LOC syndrome.

Inheritance:

LOC syndrome follows an autosomal recessive inheritance pattern. This means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. Parents who each carry one copy of the mutated gene usually do not exhibit any signs or symptoms of LOC syndrome themselves.