Genetics Home Reference: X-linked infantile spinal muscular atrophy
X-linked infantile spinal muscular atrophy is a condition that affects only boys and is characterized by severe muscle weakness and absent reflexes (areflexia). Affected children often have multiple joint deformities (contractures) from birth that cause joint stiffness (arthrogryposis) and impair movement. In severe cases, affected infants are born with broken bones. The muscle weakness worsens… Read More »