What is the inheritance pattern of Duchenne muscular dystrophy?

Duchenne muscular dystrophy (DMD) is an inherited disorder primarily affecting males that is caused by a mutation in the dystrophin gene located on the X chromosome. This inheritance pattern is classified as X-linked recessive.

In X-linked recessive conditions, males who are hemizygous for the X chromosome (having only one X chromosome) will express the disease phenotype if they inherit a mutated allele. Females, on the other hand, have two X chromosomes and are typically carriers if they inherit one mutated allele, often remaining asymptomatic unless they also inherit a second mutated allele, which can occur in rare cases.

This is contrasted with other inheritance patterns such as autosomal dominant, where only one mutated copy of a gene is sufficient to cause the disorder; autosomal recessive, where two copies of a mutated gene are necessary for the disease to manifest; and mitochondrial inheritance, which involves genes in mitochondrial DNA passed down from the mother to all her children.

Understanding the X-linked recessive nature of DMD is critical, as it informs genetic counseling, risk assessment for family members, and awareness of the likelihood of occurrence in future generations.