Jacobsen syndrome (JS) is a rare contiguous gene disorder characterized by a deletion within the distal part of the long arm of chromosome 11 ranging in size from 7 to 20 Mb. The clinical findings include characteristic dysmorphic features, growth and psychomotor delays and developmental anomalies involving the brain, eyes, heart, kidneys, immune, hematologic, endocrine, and gastrointestinal systems. The majority of cases are due to a terminal deletion of 11q; however interstitial deletions have also been reported. We report on a child with clinical manifestations consistent with JS who had a 2.899 Mb interstitial deletion at 11q24.2-q24.3 which is the smallest interstitial deletion reported so far to our knowledge. This deletion includes the KIRREL3 gene, and given our patient's history of neurocognitive delay and autism spectrum disorder, it raises the possibility that this gene is a candidate for the social and expressive language delay observed in our patient.