221WDR45 (Genetic Disorder)
222Wells Syndrome (韋爾斯綜合症)
223West Syndrome-Infantile Spasms (韋氏症-嬰兒痙攣症)
224Williams Syndrome (WS) (威廉氏症候群)
225Wilson's Disease (WD) (威爾森氏症)
226Wolf-Hirschhorn Syndrome (WHS) (沃夫-賀許宏氏症候群)
227Wolfram Syndrome (Wolfram症候群)
228Worster-Drought Syndrome (WDS)
229WWOX Syndrome (Genetic Disorder)
230Xeroderma Pigmentosum (XP) (著色性乾皮症)
231X-linked Agammaglobulinemia (XLA) (X-連鎖無丙種球蛋白血症)
232X-linked Hypophosphatemic Rickets (XLH) (性聯遺傳型低磷酸鹽佝僂症)
233X-linked Myotubular Myopathy (XLMTM) (肌小管病變)
234X-linked Retinoschisis (XLRS) (Genetic Disorder)
235X-linked Thrombocytopenia (XLT) (Genetic Disorder)