Final answer:
SMA 1-Werdnig-Hoffman is a severe form of spinal muscular atrophy that is diagnosed before the age of 2 and typically results in mortality by the age of 2 due to respiratory failure.
Step-by-step explanation:
SMA 1-Werdnig-Hoffman is a severe form of spinal muscular atrophy (SMA) that is typically diagnosed before the age of 2. This genetic disorder affects the motor neurons in the spinal cord, leading to muscle weakness and atrophy. The majority of individuals with SMA 1-Werdnig-Hoffman do not survive beyond the age of 2 years old due to respiratory failure.