Y染色体长臂(Yq)的长度因人种、民族和个体差异而有所不同。Yq的长度主要取决于Yq上的异染色质(heterochromatin, Yqh)的长度。我们于1977年发现一例伴有长Y染色体的肌萎缩侧索硬化病者,其父表型正常,但带有两种不同长度的Y染色体。此现象较罕见,文献中曾报道过一例。临床资料先证者时××,男性,28岁。体检时发现眼轮匝肌肌力差,舌肌震颤明显,咽反射活跃,吞咽困 The length of the Y-chromosome long arm (Yq) varies according to race, ethnicity and individual differences. The length of Yq depends mainly on the length of the heterochromatin (Yqh) on Yq. We found in 1977 that a patient with amyotrophic lateral sclerosis with a long Y chromosome had a normal phenotype but two Y chromosomes of different lengths. This phenomenon is rare, a case has been reported in the literature. Clinical data Proxemia × ×, male, 28 years old. Physical examination found that orbicularis muscle strength, tongue tremor obvious, active pharyngeal reflex, dysphagia