Cutaneous Manifestations of NAXD or NAXE Deficiency: A Literature Review for the Dermatologist

Nicotinamide adenine dinucleotide phosphate hydrate dehydratase (NAXD) and nicotinamide adenine dinucleotide phosphate hydrate epimerase (NAXE) deficiencies are rare autosomal recessive metabolic disorders characterized by severe neurological manifestations during infancy. In affected individuals, febrile illnesses can trigger progressive encephalopathy often accompanied by distinctive skin eruptions, resulting in high mortality rates. This study reviews the literature on NAXD/NAXE deficiencies, focusing on dermatological manifestations and their correlation with genotypic variations and treatment responses. A comprehensive literature search identified 45 patients with 31 pathogenic/likely pathogenic mutations, and a median age of onset at 1.16 years. Patients with NAXE deficiency exhibited a broader range of age of symptom onset compared to those affected with NAXD deficiency. Fever or infections were identified as the most common triggers for decompensation episodes. Skin manifestations were observed in 31% of patients with whole cell NAXD and NAXE deficiencies. The characteristic skin eruption comprises well-demarcated erythematous and erosive plaques progressing to blistering and necrosis, predominantly affecting flexural surfaces. The mortality rate was 78%, with survivors experiencing varying degrees of neurological sequelae. Niacin/nicotinamide supplementation resulted in improvements in skin lesions and survival rates. The review underscores the critical role of dermatologists in early diagnosis and intervention of NAXE and NAXD deficiencies. Recognizing characteristic skin manifestations is essential, particularly in patients with acute neurological decline following infections or vaccinations. Early intervention with specific supplements shows promise; however, further research is needed to establish standardized treatment protocols and enhance patient outcomes.