DRD4 and Menkes disease: Table 4 details the breakdown into individual professional groups, additionally distinguishing a relatively well-represented group of nurses (n = 37). There was also a statistically significant difference between the groups (Kruskal–Wallis test), but post hoc tests did not detect any significant differences. On the other hand, a homozygote carrying two DRD4-7R alleles was found in two non-MD individuals—a clinical psychologist and a nurse.