What genetic disorder is caused by mutations in the SMN1 gene?

• A. Spinal muscular atrophy
• B. Duchenne muscular dystrophy
• C. Fragile X syndrome
• D. Cystic fibrosis

Answer: (A)

Spinal muscular atrophy is a genetic disorder linked to mutations in the SMN1 gene (Survival Motor Neuron 1). This gene plays a crucial role in the survival of motor neurons, which are responsible for controlling voluntary muscle movements. The absence or malfunction of the protein produced by the SMN1 gene leads to the degeneration of these motor neurons, resulting in muscle weakness and atrophy.

The condition primarily affects infants and can present as varying degrees of weakness and muscle control issues, which can severely impact quality of life and mobility.

In contrast, other conditions listed are caused by different genetic mutations: Duchenne muscular dystrophy is associated with mutations in the dystrophin gene, Fragile X syndrome results from mutations in the FMR1 gene, and cystic fibrosis is caused by mutations in the CFTR gene. Each of these disorders has distinct genetic underpinnings and clinical manifestations, differentiating them from spinal muscular atrophy.