ENPP1 homozygous stop-loss variant causing generalized arterial calcifications of infancy: About a severe neonatal clinical case.

Generalized Arterial Calcifications of Infancy (GACI) is an extremely rare autosomal recessive genetic condition, mostly due to pathogenic variations in the ENPP1 gene (GACI1, MIM #208000, ENPP1, MIM #173335). To date 46 likely pathogenic or pathogenic distinct variations in ENPP1 have been described, including nonsense, frameshift, missense, splicing variations, and large deletions. Here we report a case of GACI in a male newborn with a homozygous stop-loss variant in ENPP1 treated in Nancy Regional University Maternity Hospital. Based on proband main clinical signs, clinical exome sequencing was performed and showed a deletion of one nucleotide leading to frameshift and stop-loss (NM_006208.3 (ENPP1):c.2746del,p.(Thr916Hisfs*23)). Clinical presentation is characterized by primary neonatal arterial hypertension resulting in hypertrophic cardiomyopathy decompensated by three cardiogenic shocks and a neonatal deep right sylvian stroke. The child died at 24 days of life. This is the first report of a pathogenic stop-loss variant in ENPP1. It is an opportunity to remind clinicians of GACI disease, a rare and severe etiology in neonates with severe hypertension, and possibility of bisphosphonates therapy.