Search

Hallucinations, disturbances of thought and delusions could all be regarded as dysfunction in the transformation of thought to speech [1]. In a recent review by Crow a very intriguing theory was described. He assumes that epigenetic variation of chromosomal rearrangements which occurred in the speciation of hominids and later on in the speciation of Homo sapiens may be associated with schizophrenia [2]. One of the hottest candidates is a gene pair: protocadherin X and Y on the X and Y chromosomes. They are linked to the asymmetry of the human brain [3,4]. There is an additional mechanism conceivable for some of schizophrenia cases. DNA sequence variation of the gene protocadherin Y could contribute in those cases to psychosis. An elaborate population based study with the main focus on immigrants is currently under way in the Netherlands. Remarkably, whereas the risk was very high for first and second generation Moroccan males, the risk for Moroccan females, first or second generation, was not significantly increased. The authors suggest a hypothesis which includes psychosocial factors. But they mention that for Turkish immigrants where were no significant elevation in their risk to develop schizophrenia in regard to the indigenous Dutch population [5]. Therefore social problems can not sufficiently explain the immense elevated risk seen in Moroccan men. A possible explanation could be DNA sequence variation of the gene protocadherin Y. It could be accountable for the six fold higher risk to develop schizophrenia in Moroccan males. As a conclusion genetic studies should be conducted to test this hypothesis. This genetic study could be linked to an MRI study in this particular patient group.