261Wolf-Hirschhorn Syndrome (WHS) (沃夫-賀許宏氏症候群)
262Wolfram Syndrome (Wolfram症候群)
263Worster-Drought Syndrome (WDS)
264WWOX Syndrome (Genetic Disorder)
265Xeroderma Pigmentosum (XP) (著色性乾皮症)
266X-linked Agammaglobulinemia (XLA) (X-連鎖無丙種球蛋白血症)
267X-linked Hypophosphatemic Rickets (XLH) (性聯遺傳型低磷酸鹽佝僂症)
268X-linked Myotubular Myopathy (XLMTM) (肌小管病變)
269X-linked Retinoschisis (XLRS) (Genetic Disorder)
270X-linked Thrombocytopenia (XLT) (Genetic Disorder)