Kleefstra syndrome 1 and ring chromosome 9 in a case

Objective To analyze the clinical and molecular genetic characteristics of patient with Kleefstra syndrome 1. Methods Clinical data, chromosomal karyotype and whole genome copy number variations (CNVs) of the patient were analyzed. Results The patient was found to have a karyotype of 45, XX, -9[4]/46, XX, r(9)(p24q34)[56]. Whole-genome CNVs detection revealed that she has carried a heterozygous deletion of approximately 670 kb at 9q34.3, which encompassed the entire EHMT1 gene. The region is strongly associated with Kleefstra syndrome (1/9q telomere deletion). In addition, the patient also had heterozygous deletion of 9pter, which may predispose to formation of ring chromosome 9. Conclusion The child was diagnosed with Kleefstra syndrome type 1 in conjunct with ring chromosome 9. Key words: Kleefstra syndrome 1; 9q34.3 microdeletion; EHMT1 gene; Ring chromosome 9