ABSTRACT
Background: PRPS1 deficiency spectrum is an X-linked condition caused by pathogenic variants in PRPS1, which encodes for the PRPP enzyme involved in the purine synthesis pathway, among other metabolic pathways. Severely affected individuals, also known as Arts syndrome, have congenital sensorineural hearing loss, optic atrophy, developmental delays, ataxia, hypotonia, and recurrent infections. Infections often precipitate worsening of symptoms and many individuals pass away in childhood. Mildly to moderately affected individuals can have isolated hearing loss, also known as DFNX1, or hearing loss with later onset ataxia and optic neuropathy concerns, also known as CMTX5. Given the importance of PRPP in the role of purine synthesis as well as other cellular processes, including formation of NAD(P), supplementation of these pathways is a logical approach for these patients. 2 Arts syndrome patients were previously supplemented with S-adenosylmethionine, starting in mid-childhood, with improvement in infection severity and frequency, as well as stabilization of other symptoms. Recently another Arts syndrome patient was supplemented with S-adenosylmethionine and nicotinamide riboside, starting in early childhood, with improvement in infection frequency and developmental gains. Here we present a now 23 month old male patient with severe PRPS1 deficiency spectrum symptoms, who was started on S-adenosylmethionine and nicotinamide riboside supplementation. Result(s): This is a 23 month old male with developmental delay, retinal dystrophy, congenital bilateral sensorineural hearing loss, and hypotonia with a PRPS1 c.383A > T / p.Asp128Val likely pathogenic variant. He does not have a history of recurrent infections, however family reports relative isolation due to the Covid-19 pandemic. He sat unsupported at 10 months, crawled at 14 months, pulled to stand at 18 months, and is nonverbal. His uric acid testing was in the low range of normal. He had normal purine testing with low normal xanthine and hypoxanthine levels. At 19 months the patient started 20 mg/kg/d S-adenosylmethionine supplementation. At 20 months this was increased to 40 mg/kg/d S-adenosylmethionine and he started on 30 mg/kg/d nicotinamide riboside supplementation. Parents reported subjective improvement in strength and endurance with supplementation. He made significant developmental gains including walking with a walker. He had done well with occasional upper respiratory infections without regression in skills, worsening hypotonia, or increased respiratory needs. Unfortunately, very recently he had a cardiac arrest secondary to respiratory failure from rhinovirus/enterovirus and H. influzenzae pneumonia, for which he remains hospitalized at this time. Conclusion(s): This is the 4th reported patient with severe PRPS1 deficiency treated with S-adenosylmethionine supplementation and the 2nd reported patient treated with nicotinamide riboside supplementation. Both supplements have a limited side effect profile and have a biochemical basis for consideration in PRPS1 deficiency. He initially did well on supplementation with improvements in strength and endurance, as well as developmental gains, however his current trajectory remains to be seen. Unfortunately, NAD/NADP, ADP/ATP, and similar markers were unavailable to us and we plan to continue clinical monitoring on supplementation. Further studies are needed to evaluate the effectiveness of S-adenosylmethionine and nicotinamide riboside supplementation in these patients.Copyright © 2023
ABSTRACT
The effort to use nutrients as interventions to treat human disease has been important to medicine. A current example in this vein pertains to NAD+ boosters, such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), which are in many clinical trials in a variety of disease conditions. Independent laboratories have shown that ingested NR (or NMN) has mitigating effects on metabolic syndrome in mice. V. V. Lozada-Fernández, O. deLeon, S. L. Kellogg, F. L. Saravia, et al. (mSystems 7:e00230-21, 2022, https://doi.org/10.1128/mSystems.00230-21) show that NR shifts gut microbiome contents and that the transplantation of an NR-conditioned microbiome by fecal transfer reproduces some effects of NR in mice on a high-fat diet. The involvement of the gut microbiome as a factor in NR effects is linked to changes to the gut microbiome and its activity to transform NR and downstream catabolites. This commentary draws attention to these findings and focuses on some puzzling aspects of NAD+ boosters, exploring the still murky interactions between NAD+ metabolism, energy homeostasis, and the gut microbiome.
ABSTRACT
Nicotinamide riboside (NR) has recently become one of the most studied nicotinamide adenine dinucleotide (NAD+) precursors, due to its numerous potential health benefits mediated via elevated NAD+ content in the body. NAD+ is an essential coenzyme that plays important roles in various metabolic pathways and increasing its overall content has been confirmed as a valuable strategy for treating a wide variety of pathophysiological conditions. Accumulating evidence on NRs' health benefits has validated its efficiency across numerous animal and human studies for the treatment of a number of cardiovascular, neurodegenerative, and metabolic disorders. As the prevalence and morbidity of these conditions increases in modern society, the great necessity has arisen for a rapid translation of NR to therapeutic use and further establishment of its availability as a nutritional supplement. Here, we summarize currently available data on NR effects on metabolism, and several neurodegenerative and cardiovascular disorders, through to its application as a treatment for specific pathophysiological conditions. In addition, we have reviewed newly published research on the application of NR as a potential therapy against infections with several pathogens, including SARS-CoV-2. Additionally, to support rapid NR translation to therapeutics, the challenges related to its bioavailability and safety are addressed, together with the advantages of NR to other NAD+ precursors.