Patients with defects in the ATP6AP1 gene have rarely been described. ATP6AP1-related disorders are a subtype of CDG, which result in enzyme deficiencies affecting multiple organ systems ranging from mild to life-threatening. Of the 13 patients described, all had hepatopathy, but this is the first case to be successfully transplanted. We describe two brothers who developed hyperbilirubinemia shortly after birth and progressed to liver failure, case 1 by 12 months of age, with successful transplant 2 years later, and case 2 by 4 months of age, who passed away while awaiting liver transplant. Both boys were found to have a new variant in the ATP6AP1 gene: c.932/p.Leu311Gln. Although the identified ATP6AP1 gene variant was classified as unknown significance at the time, both children's phenotypes fit with what has been described for ATP6AP1-related disorders. Therefore, this result appears to have been diagnostic for both boys. This rare type of CDG, X-linked immunodeficiency type 47 (OMIM #300972), particularly in patients who progress to liver failure requiring transplant, should be included on the differential of liver failure in infants and toddlers, and its gene should be added to the diagnostic workup for such cases.
Keywords: ATP6AP1; c.932/p.Leu311Gln; glycosylation; liver failure; x-linked immunodeficiency.
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