Background Duplication 15q11.2 - q13 characterized by autism spectrum disorder (ASD), intellectual disability, motor delays and epilepsy, particularly infantile spasms. Disease frequency in the population is 2–5: 10000, among people with ASD - 1:250–1:500.The duplication described in as an interstitial duplication20% cases and as supernumerary isocentric chromosome in 80% of cases.

Patients and methods We analyzed 5 patients 15q11-q13 duplication aged 3 to 5 years - 3 girls and 2 boys. We researched the clinical picture in 5 children with 15q11-q13 duplication syndrome. Age of children ranged from 3 years (36 months) averaging 4 years (48.2 months),3 girls and 2 boys. Array CGH was proved in 4 children, and FISH diagnostic- in one case of supernumerary isocentric chromosome 15.

Results We determined the duplication size from 437009 to 4914267 kb. One patients revealed two independent duplication the analyzed area - 15q11.2 (25199239_25199239) x3, 15q12 (27183835_27604796)x3. In one case identified variant - ish inv dup (15) (q11.2q13)(D15Z1++, D15S10++).

All patients have development delayed and mental retardation, mild to severe. Speech disorders was varying degrees, one child had echolalia. Behavioural problems were presented with autistic features (3 children), stereotypes (4 children), hyperactivity (3 children), aggression (1 child).

Elements of abdominal obesity noted in one patient. Facial features was represented flat nose, epicantic folds, broad nose tip, long filtrum.

EEG was performed in 3 patients. Typical epileptiform activity was not registered. Two children had cardiac arrhythmias: recurrent ventricular tachycardia in one patient, recurrent ectopic atrial tachycardia, transient AV block- in another.

Conclusion Duplication 15q11.2 - q13 was diagnosed in 5 patients with behavioral problem.Two patients have cardiac arrhythmias.