尿道下裂是陰莖的一種先天性缺損，是由於尿道前端不完全發育所導致的結果。從1969年到1990年，在台大醫院所收集到的臨床認為是尿道下裂之患者，總共有202位接收了染色體的分析檢查，。除去16位患者為女性染色體核型表徵外，總共有186位患者包括在此研究中，依照尿導下裂開口位置的嚴重程度，其分佈為前端開口32位(17.2%)，中端開口36位(19.3%)，後端開口118位(63.5%)。染色分析異常者，在32位前端患者中有5位(佔15.6%)，36位中端患者中有4位(佔1.1%)，118位後端患者中有11位(佔9.3%)。在尿道下裂患者，染色體異常發生的比率，是高於正常人口的發生比率，而且大部份染色體異常，是發生在性染色體上。至於染色體異常發生的比率，則與尿道下裂開口位置嚴重程度，沒有互相關聯。在本文中，異常染色體分析的圖形及意義，均加以討論，而且每一個患者所表現的差異性，也相當大，以致沒有確定的因素及尿道下裂的關聯性能夠加以建立。有76位尿道下裂患者另外含有其他身體上的異常，主要包括隱睪症，疝氣，陰囊分裂，以及性別不明等。在186位患者中，有13位患者的兄弟，亦有尿道下裂的情形，亦即家族發生率約6.9%。將來，希望經由染色體的分析及更進一步的基因研究，能夠在家族遺傳上，提供更多的訊息。

From 1969 to 1990, there were 202 chromosome analyses performed for clinically impressed hypospadiac patients in our hospital. Exculding sixteen cases of femake karyotype, there were one hundred and eighty six cases included in the study. We retrospectively reviewed their charts, and the results were analyzed. The distribution of patients according to severity of hypospadias were 32(17.2%) anterior, 36(19.3%) middel, and 118(63.5%) posterior. Chromosome anomalies were noted in 5 of 32(15.6%) anterior, 4 of 36 (11.1%) middle, and 11 of 118(9.3%) posterior hypospadiac patients. The incidence of chromosome anomaly in hypospadias was higher than that of general population, and the majority of anomalies occurred in sex chromosome. The incidence of chromosome anomaly is not correlated to the severity of hypospadias. Patterns and significance of abnormal karyotypes were discussed, and they showed great variations from one hypospadias to another, and no defenite aetiological correlations could be established. Seventy six cases had assosiated anomalies, consisting mainly of cryptorchidism, hernia, bifid scrotum, and intersex. Thirteen siblings of these 186 index cases were reported having hypospadias, accounting for a familial incidence of 6.9%.