Case Workbook for Human Genetics 9th Edition by Ricki Lewis

Exercise 2

This pedigree represents a family with congenital contractural arachnodactyly, an autosomal dominant defect in the connective tissue protein fibrillin-2 that produces underdeveloped and stiff muscles, outer ear deformities, stiff and long fingers, and sometimes heart abnormalities. Why is no one affected in the first generation?