SNP Shot: Genomic Insights

Fukuyama congenital muscular dystrophy (FCMD) is a genetic disorder primarily affecting the muscles, brain, and eyes. It belongs to a group of inherited diseases known as congenital muscular dystrophies, all characterized by muscle weakness and wasting (atrophy) that begins in infancy.

FCMD primarily affects the skeletal muscles, the muscles responsible for body movement. Initial symptoms typically manifest in early infancy, including a feeble cry, difficulty feeding, and reduced muscle tone (hypotonia). Facial muscle weakness often results in a characteristic facial appearance, featuring drooping eyelids (ptosis) and a consistently open mouth. As children grow, muscle weakness and joint contractures limit their mobility and hinder the development of motor skills like sitting, standing, and walking.

Brain development is also compromised in individuals with FCMD. They exhibit a brain malformation called cobblestone lissencephaly, where the brain's surface becomes uneven and bumpy, resembling cobblestones. This structural abnormality causes significant delays in speech and motor skill development, as well as moderate to severe intellectual disability. Social skills, however, are typically less affected. The majority of children with FCMD are unable to stand or walk independently, although some can sit unsupported and move across the floor while seated. Seizures are also common, affecting over half of affected children.

Additional signs and symptoms of FCMD encompass impaired vision, other eye abnormalities, and a gradual development of heart problems after the age of 10. As the disease progresses, individuals may experience difficulty swallowing, potentially leading to aspiration pneumonia, a bacterial lung infection. Due to the severe medical complications associated with FCMD, the lifespan of affected individuals is generally limited to late childhood or adolescence.

Inheritance:

FCMD follows an autosomal recessive inheritance pattern. This means that for an individual to be affected, they must inherit two copies of the mutated gene, one from each parent. The parents, carrying only one copy of the mutated gene, are usually asymptomatic carriers of the condition.