241Wilson's Disease (WD) (威爾遜氏症)
242Wolf-Hirschhorn Syndrome (WHS) (沃夫-賀許宏氏症候群)
243Wolfram Syndrome (Wolfram症候群)
244Worster-Drought Syndrome (WDS)
245WWOX Syndrome (Genetic Disorder)
246Xeroderma Pigmentosum (XP) (著色性乾皮症)
247X-linked Agammaglobulinemia (XLA) (X-連鎖無丙種球蛋白血症)
248X-linked Hypophosphatemic Rickets (XLH) (性聯遺傳型低磷酸鹽佝僂症)
249X-linked Myotubular Myopathy (XLMTM) (肌小管病變)
250X-linked Retinoschisis (XLRS) (Genetic Disorder)
251X-linked Thrombocytopenia (XLT) (Genetic Disorder)