Novel de novo interstitial deletion in 2q36.1q36.3 causes syndromic hearing loss and further delineation of the 2q36 deletion syndrome

Background: Deletions of the interstitial 2q36 are uncommon and associated with varying phenotypes. However, the list of currently known phenotypes is still far complete for an understanding of the interstitial 2q36 deletion syndrome characteristics. Aims/Objectives: To identify the genetic and clinical characterization of a 6-year-old male patient suffering from a severe form of syndromic hearing loss, with brachydactyly family history. Material and Methods: We performed conventional cytogenetic analysis on the peripheral blood lymphocytes and whole exome sequencing and SNP array analysis on DNA samples from the family. Results: The proband showed signs such as bilateral sensorineural deafness, ocular hypertelorism, flat facial profile and several decayed teeth, slightly ulnar deviation of the hands, single transverse palmar crease, short stature and intellectual disability. Through cytogenetic and molecular genetic analysis, we discovered that the syndromic hearing loss was the result of a de novo 5.175-Mb microdeletion at chromosome 2q36.1q36.3 whose breakpoints had been precisely mapped by us. Conclusions and Significance: Our study warns that auditory assessment should be evaluated even if the patient with 2q36 deletion syndrome is not obviously presenting hearing loss. In addition, a comprehensive molecular genetics diagnosis involving multiple methods is important to support accurate genetic characterization of this syndrome.