SNP Shot: Genomic Insights

Monilethrix is a hair growth disorder characterized by a distinctive "beaded" appearance of individual hair strands, resembling a necklace. The term "monilethrix" is derived from Latin and Greek roots meaning "necklace hair." This beaded effect, visible under a microscope, is caused by periodic constrictions along the hair shaft. Individuals with monilethrix typically experience sparse hair (hypotrichosis) and hair that is short, fragile, and prone to breakage.

While newborns with monilethrix usually have normal hair, abnormalities emerge within the first few months. In milder cases, the condition may only affect hair on the back of the head (occiput) or the nape of the neck. More severe cases can involve the entire scalp, as well as pubic, underarm, eyebrow, eyelash, or limb hair.

In some instances, monilethrix can also affect the skin and nails. Some individuals develop keratosis pilaris, a skin condition characterized by small bumps, particularly on the scalp, neck, and arms. Nail abnormalities may also be present.

Inheritance:

Monilethrix can be inherited in different ways. When caused by a mutation in a keratin gene, it follows an autosomal dominant inheritance pattern, meaning only one copy of the mutated gene is needed in each cell to cause the disorder. Rarely, it can occur due to a new, non-inherited mutation in the gene. When caused by mutations in the DSG4 gene, it follows an autosomal recessive inheritance pattern, requiring both copies of the gene in each cell to be mutated. In autosomal recessive inheritance, each parent carries one copy of the mutated gene but usually shows no symptoms of the condition themselves.