(1/8) #ACE2, which also likely coats the virus and hijacks the B(0)AT1 / #SLC6A19 amino acid transporter pathway, is the viral entry mechanism for #SARSCoV2. ACE2 is a co-receptor with SLC6A19. Hartnup disease (en.wikipedia.org/wiki/Hartnup_d…) is characterized by mutations in #SLC6A19. 
(2/8) If #SARSCoV2 #COVID #coronavirus is interfering with the ACE2-B(0)AT1 complex (see structural data below and at biorxiv.org/content/10.110…), and/or collectrin (which shares significant homology with ACE2 and is an unexplored potential mechanism of entry for SARS as well)...
(3/8) ...it is mechanistically likely that we will see many symptoms of #COVID19 / #COVID / #CORONAVIRUS / #SARSCoV2 that overlap with Hartnup disease.
"Excessive amounts of amino acids, such as tryptophan, are excreted in the urine."
"Excessive amounts of amino acids, such as tryptophan, are excreted in the urine."
(4/8) "Hartnup disease is a disorder of amino acid transport in the intestine and kidneys; otherwise, the intestine and kidneys function normally, and the effects of the disease occur mainly in the brain and skin."
(5/8) "Lung damage is a major hurdle to recovery in those severe patients...various studies have shown that...vitamin B3 (...nicotinamide) is highly effective in preventing lung tissue damage. It might be a wise approach to supply this food supplement to the #COVID-19 patients."
(6/8) "With too little tryptophan in the blood, the body is unable to make a sufficient amount of the B-complex vitamin #niacinamide, particularly under stress when more vitamins are needed."
(7/8) "In patients with niacin deficiency and symptomatic disease, daily supplementation with nicotinic acid or nicotinamide reduces both the number and severity of attacks. Neurologic and psychiatric treatment is needed in patients with severe central nervous system involvement"
(8/8) Further reading:
COVID-19 infection: the perspectives on immune responses nature.com/articles/s4141…
en.wikipedia.org/wiki/Hartnup_d…
Collectrin, a homologue of ACE2, its transcriptional control and functional perspectives sciencedirect.com/science/articl…
COVID-19 infection: the perspectives on immune responses nature.com/articles/s4141…
en.wikipedia.org/wiki/Hartnup_d…
Collectrin, a homologue of ACE2, its transcriptional control and functional perspectives sciencedirect.com/science/articl…
It may also be worth exploring whether "urinary excretion of proline, hydroxyproline, and arginine remains unchanged" while "glutamine, valine, phenylalanine, leucine, asparagine, citrulline, isoleucine, threonine, alanine, serine, histidine, tyrosine, tryptophan" increases.
