Anomaly -- A deviation from the usual, something different, peculiar, or abnormal. 

A congenital anomaly is something that is unusual and different at birth. A minor anomaly in this context is defined as an unusual anatomic feature that is of no serious medical or cosmetic consequence to the patient. A minor anomaly of the feet might, for example, be curvature of the second toe so it overlaps the third toe a little. By contrast, a major anomaly might be a cleft lip and palate, a birth defect of serious medical and cosmetic consequence to the patient.