A patient with unusual features and a 69.5 Mb duplication from a de novo extra der (9): A case report

Partial trisomy 9 is a common autosomal trisomy, which is characterized by non-specific psychomotor delay, mental retardation and moderately abnormal characteristic facial features. Generally, partial trisomy 9 leads to variable phenotypes depending on the size and position of the duplicated region. However, a precise genotype/phenotype map has not been determined. The present study reports the case of a 3-year-old female with certain typical features of trisomy 9p syndrome, who presented with a number of the distinctive symptoms, as well as sensorineural hearing loss, which has not previously been associated with this trisomy. Karyotype, M-FISH and OaCGH analysis were performed on the patient and her parents. The final karyotype was determined to be 47, XX, +mar.ish der (9) (wcp9+). arr cgh 9pterq21.12 (DOCK8→LOC138225)×3. Cytogenetic results showed a de novo extra der (9) with 69.5 Mb duplication. Although the molecular mechanism underlying the hearing loss is unclear, it was proposed that the 9q13→9q21 region may be critical for hearing.