OPMD can be inherited as autosomal dominant or autosomal recessive  neuro-muscular disease. The most common mode of inheritance is autosomal dominant. Unlike in autosomal recessive disorders, in autosomal dominant OPMD presence of one copy of the mutated gene within each cell is sufficient to cause the disease. Children of an affected parent have a 50% chance of inheriting the mutant gene from an affected parent.

The mutation consists of a trinucleotide repeat in the gene PABPN1. Trinucleotide repeat mutations render instability in the defective protein created according to the mutated code of the gene. The defective protein accumulates in the muscle cells and induces premature death of these cells.