Chromosome 1p32-p31 deletion syndrome is a rare chromosomal anomaly resulting from a partial deletion of the short arm of chromosome 1. This condition is characterized by developmental delay, abnormal brain structure such as corpus callosum agenesis or hypoplasia, and distinctive craniofacial features including macrocephaly, low-set ears, anteverted nostrils, and micrognathia. Urinary tract defects, for example vesicoureteral reflux and urinary incontinence, are also frequently observed. Given its extreme rarity, it affects fewer than one individual in a million.

Individuals with chromosome 1p32-p31 deletion syndrome typically present with developmental delay and brain malformations, including abnormalities in the corpus callosum. Craniofacial dysmorphism is common, with features such as macrocephaly (which can be secondary to hydrocephalus or ventriculomegaly), low-set ears, anteverted nostrils, and a small jaw. In addition, many affected individuals experience urinary tract defects like vesicoureteral reflux and urinary incontinence. Other variable findings may include hypotonia, tethered spinal cord, Chiari type I malformation, and seizures. Not all individuals experience all features, and severity varies considerably.

Chromosome 1p32-p31 deletion syndrome results from a partial deletion on the short arm of chromosome 1. The precise genetic basis is still under investigation, and no specific gene has been identified in relation to this condition. As inheritance details are not currently available, the condition is understood to arise from a chromosomal deletion event rather than from alterations in a particular gene. Genetic counseling is advised to help families understand that, while the deletion is the underlying cause, its recurrence risk remains unclear.