SNP Shot: Genomic Insights

Progressive osseous heteroplasia (POH) is a condition characterized by the abnormal formation of bone in tissues like skin and muscle. This bone, developing outside of the normal skeletal structure, is referred to as heterotopic or ectopic bone. In POH, this process begins deep within the skin, specifically in the dermis and subcutaneous fat layers, and gradually extends into adjacent tissues such as skeletal muscles and tendons. These bony lesions within the skin can be painful and may even break down, forming open wounds called ulcers. As the condition progresses, it can affect joints, leading to reduced movement and mobility.

The signs and symptoms of POH are usually first observed in infancy. However, in some individuals, the condition may not become apparent until later in childhood or even early adulthood.

Inheritance:

POH follows an autosomal dominant inheritance pattern, meaning that only one copy of the mutated gene in each cell is enough to cause the disorder. Typically, individuals inherit one copy of each gene from each parent, and for most genes, both copies are active. However, a small number of genes have only one active copy. For these genes, either the copy from the father (paternal copy) or the copy from the mother (maternal copy) is active, depending on the gene. This parent-of-origin specific gene activation is due to a process called genomic imprinting. The GNAS gene exhibits a complex genomic imprinting pattern, with the maternal copy being active in some cells and the paternal copy active in others. POH arises when mutations affect the paternally inherited copy of the GNAS gene.