As several other uncommon, less well quantitated genetic variations occur with an OCD phenotype, including chromosomal anomalies and some other rare gene variants (SGCE, GCH1 and SLITRK1), a tentative conclusion is that OCD resembles other complex disorders in being etiologically heterogeneous and in having both highly penetrant familial subtypes associated with rare alleles or chromosomal anomalies, as well as having a more common, polygenetic form that may involve polymorphisms in such genes as BDNF, COMT, GRIN2beta, TPH2, HTR2A and SLC1A1.
An association study using a polymorphism within an intron of the SGCE gene was assessed in patients with TS and OCD versus controls, and the SGCE gene itself was screened for mutations in all TS/OCD patients, followed by direct sequencing of the gene in a limited number of these patients.
Among myoclonus-dystonia syndrome (MD) patients, psychiatric disorders including depression, anxiety, alcohol dependence, obsessive-compulsive disorder (OCD) and panic disorder have been frequently reported to be related with the epsilon-sarcoglycan gene (SGCE) mutation.