Identification of a de novo interstitial 21q22.12q22.13 deletion in a patient with intellectual disability

Objective To explore the genetic basis of a child featuring intellectual disability, developmental delay and epilepsy. Methods Cytogenetic and molecular analysis including chromosomal karyotyping analysis, single nucleotide polymorphism array (SNP array) and qPCR were performed. Results The karyotype of the child was determined as 46, XX; SNP array: arr[19]21q22.12q22.13(36 860 195-38 801 482)×1 dn. A heterozygous 1.9 Mb microdeletion was detected at 21q22.12q22.13. qPCR has confirmed deletion of exon 1 of the DYRK1A gene, which has occurred de novo. Conclusion A 21q22 deletion was diagnosed with multiple genetic methods. Genotype-phenotype correlation suggested DYRK1A to be a candidate for intellectual disability. Key words: 21q22 microdeletions; Intellectual disability; DYRK1A gene; PIGP gene