Narrowing down the region responsible for 1q23.3q24.1 microdeletion by identifying the smallest deletion.

Interstitial deletions of 1q23.3q24.1 are rare. Here, chromosomal microarray testing identified a de novo microdeletion of arr[GRCh37]1q23.3q24.1(164816055_165696996) × 1 in a patient with moderate developmental delay, hearing loss, cryptorchidism, and other distinctive features. The clinical features were common to those previously reported in patients with overlapping deletions. The patient's deletion size was 881 kb-the smallest yet reported. This therefore narrowed down the deletion responsible for the common clinical features. The deleted region included seven genes; deletion of LMX1A, RXRG, and ALDH9A1 may have caused our patient's neurodevelopmental delay.