Almost always, the sickle cell mutation is a non-conservative missense mutation that results in the sixth amino acid of beta-globin being valine instead of glutamic acid.

镰状细胞突变几乎总是由于非保守区错义突变，导致β-珠蛋白的第6个氨基酸为缬氨酸，而非谷氨酸。

On the other hand, mutations that allow for a misshapen protein to form, like missense mutations, lead to Becker muscular dystrophy which is basically a milder form of Duchenne muscular dystrophy that presents later on, usually between age 10 to 20.

另一方面，突变（如错义突变）会导致畸形蛋白形成，引发BMD，病情比DMD较轻，发病年龄较晚，一般在10到20岁。