Expanding the genotypic spectrum of PCSK1 deficiency: A novel mutation in severe neonatal diarrhea.

Among congenital diarrhea and enteropathies (CODEs), proprotein convertase subtilisin/kexin type 1 (PCSK1) deficiency is a rare monogenic disorder, associated with severe neonatal diarrhea and polyendocrinopathies. We report an 18-day-old male neonate, born to consanguineous parents, presenting with persistent watery diarrhea, metabolic acidosis, and failure to thrive. Genetic analysis identified a novel homozygous c.709+1 G > A splicing mutation in PCSK1, predicted to disrupt protein function. Rapid genetic diagnosis enabled timely endocrine assessment and guided nutritional management, minimizing invasive procedures. Expanding the PCSK1 mutational spectrum, this case highlights the pivotal role of next-generation sequencing in neonates with refractory diarrhea and suggestive clinical history, facilitating early intervention and improved outcomes.