“Those who might have gotten Skeletal Muscular Atrophy (SMA) are within the approximately 10,000 to 25,000 children and adults are living with SMA in the United States. It’s a rare disease that affects one out of 6,000 to 10,000 children.

A person with SMA inherits two copies of a missing or faulty (mutated) survival motor neuron 1 (SMN1) gene. One faulty gene comes from the mother and the other comes from the father. An adult can have a single copy of the defective gene that causes SMA and not know it.

About six million Americans (1 in 50) carry the mutated SMN1 gene. These carriers have one healthy SMN1 gene and one missing or defective SMN1 gene. Carriers don’t develop SMA. There’s a 1 in 4 chance that two carriers will have a child with SMA.”

Cleveland Clinic (https://my.clevelandclinic.org/health/diseases/14505-spinal-muscular-atrophy-sma)