肌营养不良(muscular dystrophy)
使得骨骼肌（有时是心肌）日益无力的一种遗传病。肌肉组织随意退化和再生，并被疤痕组织和脂肪取代。无特效疗法。物理治疗、支架和矫正手术可能有所帮助。迪歇恩氏营养不良是最常见的类型，只发病於男性。包括常跌倒和站立困难的症状发生於三～七岁的男孩身上；从腿到手臂再到横膈膜肌肉，肌肉逐渐损耗。後因肺部感染或呼吸衰竭通常在二十岁之前就引起死亡。该种基因能在女性携带者和男婴上测到。贝克尔氏营养不良也和性别相关，没有这麽严重，发病较晚。病人能够继续行走，通常能活到他们三四十岁。肌强直性营养不良，男女两性均可患病，肌强直两到三年後恶化，伴随白内障、脱发和性腺萎缩。肢带型营养不良侵袭两性的骨盆和肩部肌肉。面肩胛肱骨型（面部、肩刃和上臂）营养不良始於童年或青年时期，两性均可患病；最初症状为举臂困难，下肢和骨盆肌肉也会受累；主要的面部影响是闭眼困难。平均寿命很正常。
English version：
muscular dystrophy
Inherited disease that causes progressive weakness in the skeletal (and occasionally heart) muscle. Muscle tissue degenerates and regenerates randomly and is replaced by scar tissue and fat. There is no specific treatment. Physical therapy, braces, and corrective surgery may help. Duchenne's muscular dystrophy, the most common, strikes only males. Symptoms, including frequent falls and difficulty in standing up, start in boys 3-7 years old; muscle wasting progresses from the legs to the arms and then the diaphragm. Pulmonary infection or respiratory failure usually causes death before age 20. The gene can now be detected in female carriers and male fetuses. Becker's dystrophy, also sex-linked, is less severe and begins later. Patients remain able to walk and usually survive into their 30s and 40s. Myotonic muscular dystrophy affects adults of both sexes, with myotonia and degeneration two to three years later, along with cataracts, baldness, and gonadal atrophy. Limb-girdle dystrophy affects the pelvic or shoulder muscles in both sexes. Facioscapulohumeral (face, shoulder-blade, and upper-arm) dystrophy starts in childhood or adolescence and affects both sexes; after initial symptoms of difficulty raising the arms, the legs and pelvic muscles can be affected; the main facial effect is difficulty in closing the eyes. Life expectancy is normal.