Objectives:
Clinical effects observed in cases of oxytocin deficiency can also manifest themselves in disorders of mechanisms responsible, for example, for its secretion. For oxytocin, this function is played by – among others – the cluster of differentiation antigen 38 (CD38). Existing literature along with the correlation between protein CD38 and oxytocin secretion raise interest in the context of their possible relation to the clinical picture and development of the autism spectrum disorders (ASD). The aim of the study was to analyze the correlations between polymorphisms rs3796863 and rs6449197 in gene CD38, the level of gene expression and the clinical picture and the risk of ASD diagnosis.

Methods:
The study included 59 individuals with the mean age of 15.05 years with IQ > 90. The participants were divided into two groups: the studied group consisting of 37 persons with confirmed ASD diagnoses and the control group including 22 neurotypical individuals. Diagnosis verification was carried out via the ADOS-2 protocol.

Results:
The comparative analysis with the standardized population based on the 1000Genomes database with the presence of clinically significant intensification of ASD traits showed the correlation of alleles “T” of polymorphisms rs3796863 and rs6449197, which are more frequent in the general population and are treated as “wild”. In the inter-group analysis, this type of dependency was weaker, and the genotype of the control group was somehow intermediate between the studied group and the standardized population. In the ΔΔCt analysis, the normalized value of the relative expression level of gene CD38 showed that in the studied group the expression level was around 1.1–1.2 times higher than in the control group.

Conclusions:
The obtained results show that a significant correlation with the severity of autism spectrum disorder traits is mainly observed in the carriers of wild variants of the studied polymorphisms, in which the related increase in the expression level of gene CD38 is also observed.