Final answer:
Mitten hand deformity is associated with Apert syndrome, a genetic disorder caused by mutations in the FGFR2 gene, resulting in the premature fusion of bones and webbed fingers and toes.
Step-by-step explanation:
Mitten hand deformity is commonly associated with Apert syndrome, which is a genetic disorder. Apert syndrome is characterized by the premature fusion of certain skull bones, which affects the shape of the head and face. It also leads to webbing of the fingers and toes, which is why the term 'mitten hand deformity' is used to describe the hand appearance in individuals with this condition. This fusion of the digits looks like one is wearing mittens, hence the name. Apert syndrome is caused by mutations in the FGFR2 (Fibroblast Growth Factor Receptor 2) gene. The condition is rare and is usually evident at birth or early childhood.