Scapuloperoneal myopathy is inherited as an autosomal dominant trait. Human traits including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother.
In dominant disorders, a single copy of the disease gene (received from either the mother or father) will be expressed “dominating” the other normal gene and resulting in the appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child.
In some cases, scapuloperoneal myopathy may be due to new genetic changes (mutations) that appear to occur spontaneously for unknown reasons (sporadically).
Investigators have determined that some cases of scapuloperoneal myopathy may be caused by disruption or changes (mutations) of a gene located on the long arm (q) of chromosome 12 (12q13.3-q15). Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as “p” and a long arm identified by the letter “q.” Chromosomes are further subdivided into bands that are numbered. For example, “chromosome 12q13.3-q15” refers to bands 13.3-15 on the long arm of chromosome 12.