Abstract
Chromosome 15q24 microdeletion is a rare genetic disorder characterized by development delay, facial dysmorphism, congenital malformations, and occasional autism spectrum disorder (ASD). In this study, we identified five cases of 15q24 microdeletion using multiplex ligation-dependent probe amplification (MLPA) technology in a cohort of patients with developmental delay and/or intellectual disability. Two of these five cases had deletions that overlapped with the previously defined 1.1 Mb region observed in most reported cases. Two cases had smaller deletions (< 0.57 Mb) in the 15q24.1 low copy repeat (LCR) B-C region. They presented significant neurobehavioral features, suggesting that this smaller interval is critical for core phenotypes of 15q24 microdeletion syndrome. One case had minimal homozygous deletion of less than 0.11 Mb in the 15q24.1 LCR B-C region, which contained CYP1A1 (cytochrome P450 family 1 subfamily A member 1) and EDC3 (enhancer of mRNA decapping 3) genes, resulting in poor immunity, severe laryngeal stridor, and lower limbs swelling. This study provides additional evidence of 15q24 microdeletion syndrome with genetic and clinical findings. The results will be of significance to pediatricians in their daily practice.
Highlights
The rare genetic disorder 15q24 microdeletion is caused by nonallelic homologous recombination (NAHR) between low copy repeats (LCRs) in the chromosome 15 band q24 region; the overall incidence approaches 1 in 42,000 in the general population [1]
Identification of 15q24 microdeletion Of the 7077 cases examined by multiplex ligationdependent probe amplification (MLPA) P245 assay, five were found to have genomic imbalance at 15q24, with a prevalence of 1 in 1429
All five cases were further confirmed to have deletions at 15q24 by MLPA P371 assay, including those with single probe abnormalities by P245 assay, which ruled out the possibility of probe binding sequence mutation
Summary
The rare genetic disorder 15q24 microdeletion is caused by nonallelic homologous recombination (NAHR) between low copy repeats (LCRs) in the chromosome 15 band q24 region; the overall incidence approaches 1 in 42,000 in the general population [1]. To the best of our knowledge, more than 60 patients with 15q24 deletions have been described in the literature. The majority of 15q24 microdeletions identified to date involve a 1.1 Mb region between 72.2 and 73.3 Mb of the reference genome (NCBI36/hg18) [3]. A few cases were reported to have atypical deletions, involving only a. The 15q24 microdeletion can be detected by molecular methods that determine the copy number of sequences within the deleted region. In China, multiplex ligationdependent probe amplification (MLPA) is a rapid and cost effective method for detection of targeted chromosome copy number variations (CNVs). The process from DNA extraction to capillary electrophoresis can be completed within 24 h at a cost of 100 to 200 RMB
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