Which genetic disorder is characterized by an autosomal recessive inheritance pattern and leads to infant mortality?

The correct answer is spinal muscular atrophy, which is indeed characterized by an autosomal recessive inheritance pattern. This condition arises due to mutations in the SMN1 gene, leading to the degeneration of motor neurons in the spinal cord and brainstem. The severity of spinal muscular atrophy is highly variable, but the most severe form, known as type I or Werdnig-Hoffmann disease, typically presents in infancy and is associated with significant morbidity and high rates of infant mortality due to respiratory failure and muscle weakness.

Sickle cell anemia and cystic fibrosis also follow an autosomal recessive pattern, but their outcomes and presentations differ. Sickle cell anemia can lead to complications, but with advancements in management, many patients now have improved survival and quality of life. Cystic fibrosis significantly impacts life expectancy due to progressive lung disease, but many individuals live into adulthood with treatment. Turner's syndrome, in contrast, is a chromosomal condition resulting from the absence of all or part of a second sex chromosome and does not follow an autosomal recessive inheritance pattern.

Thus, spinal muscular atrophy, particularly its most severe form, is correctly linked to both the specific inheritance pattern and the potential for infant mortality.