Biallelic PAN2 variants in individuals with a syndromic neurodevelopmental disorder and multiple congenital anomalies.

PAN2 encodes a subunit of a deadenylation complex with important functions in mRNA stability and post-transcriptional regulation of gene expression. A homozygous frameshift deletion in PAN2 was reported in a single affected individual with developmental delay and multiple congenital anomalies. Here, we describe five additional individuals from three unrelated families with homozygous predicted loss-of-function variants in PAN2. The affected individuals presented with significant overlap in their clinical features, including mild-moderate intellectual disability, hypotonia, sensorineural hearing loss, EEG abnormalities, congenital heart defects (tetralogy of Fallot, septal defects, dilated aortic root), urinary tract malformations, ophthalmological anomalies, short stature with other skeletal anomalies, and craniofacial features including flat occiput, ptosis, long philtrum, and short neck. Our data confirm that biallelic predicted loss-of-function variants in PAN2 cause a syndrome with multiple congenital anomalies, and suggest an important role of mRNA polyA tail length for proper organ formation.