[The familial undescended testis]

Testicular maldescent affects 1 % of all 1 year old boys. The observation of familial undescended testis (UDT) was confined to the description of individual cases respectively particular families. The aim of our study was to evaluate the frequency of a positive family history and the frequency of associated urological anomalies in family members and to calculate the risk for new born male individuals to have UDT if a family member is affected.

74 patients who underwent surgery because of UDT and 374 matched controls without UDT (control group) were interviewed by means of a special questionnaire. We asked for a family history of UDT, as well as for other urogenital anomalies respectively organ alterations (varicocele, hydrocele, hypospadia, testicular cancer, renal anomalies) and reviewed the medical records. For statistical analysis the odds ratio were calculated.

85/374 (22.73 %) of the analysed patients had family members with UDT versus 28/374 (7.5 %) of the control group. Brothers were involved in 37.3 %, fathers in 35.2 %, uncles in 23.5 %, cousins in 16.5 %, great-cousins in 8.2 % and grandfathers in 7.1 %. The familial cluster (risk for UDT in new born male) is 3.6-fold over all (2.306; 5.727), 6.9-fold if a brother and 4.6-fold if the father is affected. The rate of family members with UDT and/or other urogenital anomalies in the patients group was nearly 2-fold higher as in the control group (14 % versus 7.8 %).

In our series the presence of UDT is much more frequently present than described in the literature so far. Due to the high familial cluster and the higher percentage of a positive family history for UDT and/or other urogenital anomalies in patients with UDT, a genetic predisposition is probable. Male descendants show a 3.6-fold increased risk in relation to the normal population, if a family member is already affected.