Hartnup Disease: The Inherited Disorder of Tryptophan Absorption

Table of Contents

1. What Hartnup Disease Is
2. The Transporter Behind It
3. The Hartnup Family and the Gene Hunt
4. How It Is Inherited and How Common It Is
5. Signs Reported in People With Symptoms
6. Most Children Found by Screening Stay Well
7. How Hartnup Disease Is Diagnosed
8. What Case Reports Describe After Treatment
9. The Tryptophan and Niacin Connection
10. Adult Onset and Unusual Presentations
11. What Is Not Known
12. Key Research Papers
13. Connections
14. Featured Videos

What Hartnup Disease Is

Every meal that contains protein is broken down in the gut into single amino acids, which special "doorway" proteins in the lining of the small intestine pull into the body. The kidneys do a similar job in reverse: they filter amino acids out of the blood and then reclaim almost all of them before urine leaves the body. Hartnup disease is a fault in one of these doorways.

Researchers describe it as an autosomal recessive abnormality of neutral amino acid transport in the kidney and the gut, noted for how differently it shows up from one person to the next (Seow 2004). "Neutral" refers to amino acids that carry no overall electric charge. The group includes tryptophan as well as several other essential amino acids. Because the doorway is faulty, these amino acids are poorly absorbed from food and are lost in large amounts in the urine.

The medical literature uses both names, "Hartnup disorder" and "Hartnup disease." A 1987 study of children found by newborn screening summed up the distinction in its title: a "Mendelian transport disorder" (one caused by a single gene) and a "multifactorial disease" (one that depends on several factors at once) (Scriver 1987).

The Transporter Behind It

The doorway protein is called broad neutral amino acid transporter 1 (B0AT1). Its gene is SLC6A19. Laboratory work found that the transporter depends on sodium but not on chloride, carries an electric current as it works, and actively moves most neutral amino acids into cells (Bröer 2005). Tissue studies showed strong expression in the finger-like villi of the small intestine and in the first stretch of the kidney's filtering tubes, the proximal tubule. Its expression was restricted to kidney, intestine and skin (Bröer 2005).

The transporter does not work alone. It needs a partner protein to reach the cell surface: collectrin in the kidney and angiotensin-converting enzyme 2 (ACE2) in the intestine (Bröer 2009). The same review notes that this ties SLC6A19 to more complex functions such as blood pressure control and the structure of the kidney's filters (Bröer 2009). Angiotensin-converting enzyme 2 has also received major attention as the receptor the COVID-19 virus uses to enter cells (Kravetz 2023). A 2021 hypothesis paper proposed that the virus, by binding intestinal angiotensin-converting enzyme 2, reduces the absorption of neutral amino acids, drawing on research into Hartnup disorder; the authors labelled it a hypothesis with no level of evidence (Nisoli 2021).

Collectrin matters for another reason. In 2019, researchers described an 11-year-old boy and a 22-year-old man with deletions affecting the collectrin gene (CLTRN) who had neutral amino acids in their urine and neuropsychiatric problems, including autistic features, anxiety, depression, compulsions and motor tics. Both had been given a clinical diagnosis of Hartnup disease and treated with niacin, although their blood amino acid levels were normal. The authors proposed that collectrin deficiency can produce a picture similar to Hartnup disease (Pillai 2019).

The Hartnup Family and the Gene Hunt

The condition is named after an English family described in 1956 (Kleta 2004). That year, a team published a report in The Lancet whose title listed what they had found: a hereditary pellagra-like skin rash, a temporary cerebellar ataxia (loss of balance and coordination), a constant amino acid leak into the urine, and "other bizarre biochemical features" (Baron 1956). The family's surname became the name of the condition.

For decades the cause stayed unknown. Gene-mapping work in a Japanese family and in six Australian families eventually placed the gene on the short arm of chromosome 5, in a region called 5p15 (Bröer 2005). In 2004, two research groups published back to back in Nature Genetics:

• A team led from the National Human Genome Research Institute returned to the original family in whom Hartnup disorder was discovered. They confirmed the gene region on chromosome 5p15, isolated the human gene SLC6A19, and found mutations in members of that original family and in three Japanese families (Kleta 2004).
• A team led from the University of Sydney mapped the gene to chromosome 5p15.33, cloned SLC6A19, and found six mutations that travelled with the disease in the expected recessive pattern. Most affected people carried two different mutations, one from each parent. The mutations they tested reduced amino acid transport in laboratory cells (Seow 2004).

A 2005 review by the Australian group reported that ten mutations had been identified by then, and that one of them occurs in members of the original 1956 family, "thereby defining SLC6A19 as the 'Hartnup'-gene" (Bröer 2005). By 2009 the count had reached 21 mutations in more than twenty families (Bröer 2009).

The two 2004 papers did not find both faulty copies in every affected person, which raised the idea that a second gene might be involved. A 2008 study of six new Australian and Canadian (Quebec) families, plus one American family in whom no mutation had been found, identified seven more SLC6A19 mutations. These explained Hartnup disorder in all reported families so far and showed that two faulty copies of SLC6A19 are needed for the typical urine pattern (Azmanov 2008).

How It Is Inherited and How Common It Is

Hartnup disease is autosomal recessive. A person has the condition only when both copies of SLC6A19, one from each parent, carry a disease-causing change. Parents who each carry one changed copy are usually healthy carriers. A 2018 report from China describes exactly this: a female patient with two new SLC6A19 mutations, one inherited from her father and one from her mother, both of whom were healthy carriers (Zhu 2018).

Some figures on how common the gene changes are come from the studies read for this page:

• New South Wales, Australia. Routine urine screening of 6-week-old infants put the incidence of Hartnup disease at approximately 1 in 33 000 (Wilcken 1977).
• Allele frequencies. The 2004 Sydney study gave population frequencies of 0.007 for the most common mutated allele (517G>A) and 0.001 for the next (718C>T) (Seow 2004).
• An ancient shared mutation. One mutation, called D173N, was found on 42% of Hartnup chromosomes from apparently unrelated families in Australia and North America. Everyone carrying it shared the same surrounding stretch of DNA, pointing to a single common ancestor, and the analysis suggested the allele is more than 1000 years old. The authors proposed that it survived because it does not completely shut down the transporter (Azmanov 2007).

Pregnancy has also been studied. A 1986 report followed childbearing in two women with Hartnup disorder. Two children born after untreated and uneventful pregnancies had normal growth and development. A third child had a neural tube defect and died at 3 months; that mother had a family history of major birth defects. The authors concluded that, unlike phenylketonuria, Hartnup disorder in the mother did not appear to harm the fetus in their experience (Mahon 1986).

Signs Reported in People With Symptoms

The 2004 gene paper summarised the classic picture as passing episodes of pellagra-like rashes, cerebellar ataxia and psychosis (Kleta 2004). A medical reference text adds amino acids and a substance called indican in the urine, anxiety, depression and mild intellectual disability, and notes that symptoms come and go, influenced by environmental factors, season, stress and poor nutrition (Hashmi 2023).

The signs described across reviews and case reports fall into a few groups:

• Skin. A photosensitive rash, meaning one brought on or worsened by light, is the best-known sign (Bröer 2009). Some children have had eruptions that looked like other skin diseases. A girl reported from Turkey first presented with a rash resembling acrodermatitis enteropathica, a zinc-related condition, before Hartnup disease was diagnosed (Seyhan 2006). An 11-month-old girl with Hartnup disease presented with kwashiorkor, a form of severe protein malnutrition, with similar skin lesions and a normal zinc level (Orbak 2010).
• Balance and movement. Cerebellar ataxia, an unsteady, wide-based walk with poor coordination, is part of the original description (Baron 1956; Kleta 2004). A 6-month-old girl in Boston had episodes of abnormal twisting postures of the legs (dystonia) and eczema-like skin changes without ataxia (Darras 1989).
• Mind and mood. Psychosis, anxiety and depression appear in reviews (Kleta 2004; Hashmi 2023). A 10-year-old girl in India had skin eruptions, ataxia, mental changes and diarrhoea, the full picture of niacin deficiency, together with the neutral amino acid pattern in her urine (Patel 2008).
• Seizures and nerve damage. A Korean boy aged 8 years had seizures, attention problems and intellectual disability without any rash or ataxia (Cheon 2010). In a female patient reported from China, Hartnup disorder showed itself only through seizures (Zhu 2018). Two unrelated young men reported from Beijing had spastic weakness of the legs and severe damage to the nerves of the lower limbs, alongside intermittent brain dysfunction and light-sensitive rashes (Wang 2022).

Severe outcomes have also been reported. A 1976 study described a family in which three siblings had an intermittently progressive neurological disease; two of them had the Hartnup urine pattern. Examination of one sibling's brain after death showed severe diffuse shrinkage, loss of nerve cells in the cortex and loss of Purkinje cells in the cerebellum (Tahmoush 1976).

Most Children Found by Screening Stay Well

Several regions once screened the urine of newborns for amino acid disorders, and these programmes produced the clearest picture of what Hartnup disorder does when it is found before any symptoms appear.

• New South Wales, 1977. Hartnup disease was diagnosed in 12 children and 3 of their 15 brothers and sisters through routine urine screening of 6-week-old infants. They were followed for up to 8 years. In that time there were only two clinical episodes that might be ascribed to Hartnup disease, and mental development was normal in all the children. The authors concluded that in Australian children with Hartnup disease, symptoms are very uncommon (Wilcken 1977).
• North America, 1987. A study compared 21 people with the Hartnup transport fault, all found through newborn screening, with 19 of their brothers and sisters. It found no significant difference in average growth or IQ scores. All the low academic performance scores were in the Hartnup group, and five Hartnup subjects had various skin lesions. Only two had clear clinical problems: impaired growth and IQ in one, impaired growth and a pellagra-like episode in the other. Those two had the lowest combined blood levels of the affected amino acids in the Hartnup group, and their brothers and sisters were the low outliers among the controls (Scriver 1987).
• One million babies, 1980. A long-term follow-up of one million infants screened at 6 weeks of age listed Hartnup disease among the most frequent abnormalities found. The authors judged that early diagnosis brought "probable benefit" to some patients with Hartnup disease, and unequivocal benefit only for phenylketonuria (Wilcken 1980).

The Quebec urinary screening programme, running since 1971, has screened more than 2,500,000 newborns for 25 inherited disorders, including Hartnup syndrome among the amino acid transport disorders (Auray-Blais 2007).

The 1987 study drew a general lesson from these results: the transport fault is set by one gene, but the blood level of the affected amino acids is shaped by many genes and sets each person's liability to disease (Scriver 1987). A 2005 review described the lost amino acids as thought to be made up for by a protein-rich diet, with more severe symptoms developing when a poor diet and other factors are added (Bröer 2005).

How Hartnup Disease Is Diagnosed

The urine amino acid pattern. Raised levels of several neutral amino acids in the urine are the first indicator of the disorder (Cheon 2010). Laboratories measure the amino acids in a urine sample and look for the typical "Hartnup" pattern.

A ratio that separates Hartnup from look-alikes. The pattern is not always clean. A 2020 study from Utrecht compared 27 urine samples from 11 people with genetically confirmed Hartnup disorder with 68 samples from 16 people with other kinds of amino acid loss in the urine. People with Hartnup disorder also lost many amino acids not classically linked to it, which can lead to a misdiagnosis of generalized aminoaciduria and to vitamin B3 treatment being withheld. The researchers calculated a ratio of the "Hartnup amino acids" to the other amino acids. It was 6.1 (range 2.4 to 9.6) in the Hartnup group and 0.2 (range 0.0 to 1.6) in the comparison group, with no overlap between the two (Haijes 2020).

Blood amino acids. Low levels of neutral amino acids in the blood have been reported in symptomatic cases. In the 2024 German adult case, tryptophan could not be detected at all (Bachmann 2024). In the collectrin cases, by contrast, blood amino acids were normal (Pillai 2019).

Genetic testing. Sequencing the SLC6A19 gene confirms the diagnosis by finding two disease-causing changes (Azmanov 2008). In recent reports, whole-exome sequencing, which reads all the protein-coding parts of a person's genes at once, found the variants in adults whose illness had puzzled several specialist teams (Bachmann 2024; Wang 2022). The authors of the 2024 case wrote that metabolic testing and whole-exome sequencing are recommended in rapidly progressive neuropsychiatric disease, especially with additional neurological signs and when standard treatment fails (Bachmann 2024).

Conditions in the differential. Nutritional pellagra, zinc deficiency and protein malnutrition can all produce similar skin findings (Seyhan 2006; Orbak 2010). Two children with both coeliac disease and Hartnup disease have been described, and in one of them the gluten-free diet alone did not bring improvement (Ciecierega 2014; Sander 2009).

What Case Reports Describe After Treatment

The studies found for this page include no randomised trial of any treatment for Hartnup disease. What is known comes from case reports and small series, and the findings below are reported as such.

• Vitamin B3. Several reports describe improvement after niacin. A 3-year-old girl with long-lasting diarrhoea, low blood protein and a peeling red rash, first diagnosed with coeliac disease that did not respond to a gluten-free diet, showed "dramatic improvement" after niacin was started (Ciecierega 2014). The Utrecht team refers to vitamin B3 as the treatment that a missed diagnosis would withhold (Haijes 2020). The two collectrin patients were also treated with niacin supplementation (Pillai 2019). Vitamin B3 comes in two main forms, nicotinic acid and nicotinamide; the abstracts read for this page name "niacin" or "nicotinic acid" and do not give doses.
• Protein intake. In the 2024 German adult case, a high-protein diet together with niacin led to "rapid considerable improvement" (Bachmann 2024). A 3-year-old Iraqi girl with both coeliac and Hartnup disease showed rapid improvement in her skin lesions on a high-protein gluten-free diet with vitamin and trace-mineral supplements (Sander 2009). A 2009 review ties the transporter to protein nutrition in its title (Bröer 2009), and a 2005 review describes the losses as thought to be made up for by a protein-rich diet (Bröer 2005).
• Amino acids by vein. In the two Beijing patients, leg strength and walking improved after oral nicotinic acid together with intravenous amino acids. One man's muscle strength rose from 3/5 to 4/5 on the Medical Research Council scale, and the other's walking distance lengthened from 50 to 100 m (Wang 2022).
• Getting around the absorption fault. A 1990 note in Nutrition Reviews discussed ethyl esters of tryptophan, a chemically modified form, as a way to bypass the absorption defect (Nutr Rev 1990).

Not every symptom responded. In the Boston infant with dystonia, tryptophan given alone or with nicotinic acid failed to improve the abnormal postures; a separate medicine, trihexyphenidyl, did (Darras 1989). In the 2024 adult case, the nerve damage in the limbs (polyneuropathy) was unchanged at 4 months, even though other problems had improved (Bachmann 2024).

Sunlight. Because the rash is described as photosensitive (Bröer 2009) and symptoms vary with the season (Hashmi 2023), light exposure is part of the picture. The abstracts read for this page do not report a study of sun protection as a treatment.

Decisions about vitamins, diet and medicines for a person with an inherited metabolic condition belong with a clinician who knows the case.

The Tryptophan and Niacin Connection

The body can make some of its own niacin from tryptophan, through a long chain of reactions called the kynurenine pathway. That chemistry, and the history of the pellagra epidemics in corn-eating regions, are covered in depth on the Tryptophan and Niacin Synthesis page.

Hartnup disease fits into this story from the supply side. Reduced absorption in the intestine and kidney leads to shortages of neutral amino acids and of products made from them further down the line, including niacin, and these shortages are linked to the skin and nervous system symptoms (Kravetz 2023). A 2005 commentary argued that the shortage of amino acids in the blood is the likely cause of the symptoms, because SLC6A19 is not made in the organs that are affected (Kraut 2005).

This explains why the rash resembles nutritional pellagra so closely, and why the older literature called it a "hereditary pellagra-like" condition (Baron 1956). It also explains why diet matters so much. A person whose transporter works poorly but who eats plenty of protein may absorb enough tryptophan through other routes, while poor nutrition can tip the balance toward symptoms (Bröer 2005).

Tryptophan is also the raw material for serotonin. In the Boston infant, the level of a serotonin breakdown product (5-hydroxyindoleacetic acid) in the spinal fluid was at or below two standard deviations of normal, and an oral tryptophan load produced a two-fold rise (Darras 1989). One of the collectrin patients had low levels of the same serotonin breakdown product (Pillai 2019).

Adult Onset and Unusual Presentations

Hartnup disease is usually thought of as a childhood condition, but recent reports describe adults whose illness took a long time to recognise.

Germany, 2024. A patient in their twenties was admitted for what appeared to be a sudden worsening of an anxiety disorder. Medicines did not help, and presumed catatonic psychosis was treated with electroconvulsive therapy. The patient was then referred to neurology with reduced consciousness, mutism, obvious anxiety, stiffness of all four limbs, eczema and weight loss. Brain scans showed progressive shrinkage and white-matter damage. Autoimmune encephalitis was assumed and treated with plasma exchange, high-dose steroids and intravenous immunoglobulin, while repeated spinal fluid tests stayed normal. A metabolic work-up finally showed amino acids spilling into the urine, low neutral amino acids and undetectable tryptophan. Whole-exome sequencing found two SLC6A19 variants, one of them new. After the diagnosis, a high-protein diet and niacin led to rapid, considerable improvement. At 4 months, blood amino acids were normal, communication and behaviour were age-adequate, and the stiffness had almost resolved, while the limb nerve damage was unchanged. The authors noted that inborn metabolic diseases are often missed in adults because of a low level of suspicion (Bachmann 2024).

Beijing, 2022. Two unrelated young men carried new pairs of SLC6A19 mutations. Besides intermittent brain dysfunction and light-sensitive rashes, both had signs of hereditary spastic paraplegia and severe nerve damage. Imaging showed mild shrinkage of the cerebellum and thinning of the spinal cord in the chest region, and a nerve biopsy showed a moderate loss of nerve fibres. The authors noted that the links between particular gene changes and particular symptoms are not fully understood (Wang 2022).

A question about psychosis. A 2025 letter in a psychiatry journal took up the subject of psychosis linked to Hartnup disease, asking in its title whether it is a dwindling phenomenon or simply underreported (Colijn 2025).

Together with the seizure-only cases from Korea and China (Cheon 2010; Zhu 2018), these reports show that Hartnup disease does not always arrive with the classic rash and unsteady gait.

What Is Not Known

• Why most people stay well. Screening studies show that most people with two faulty SLC6A19 copies never become ill (Wilcken 1977; Scriver 1987). Diet and other genes are thought to play a part, but the exact factors that tip a person into symptoms are not mapped.
• Gene change and symptom. The link between particular mutations and particular symptoms, such as nerve damage or seizures, is not fully understood (Wang 2022).
• The brain. The nervous system effects have been attributed to body-wide shortages of tryptophan, because the transporter was not found in the brain. A 2023 analysis of gene-activity data found Slc6a19 activity in the ependymal cells that line the fluid spaces of the brain in mice and proposed a new role there; this has not been confirmed in people (Kravetz 2023).
• Doses and duration. No randomised trial has tested vitamin B3, protein intake or any other treatment. The abstracts read for this page do not give a dose of niacin or nicotinamide, so this page does not quote one.
• Whether some symptoms are reversible. Nerve damage persisted in the 2024 adult case despite other improvements (Bachmann 2024), and dystonia in one infant did not respond to tryptophan or nicotinic acid (Darras 1989).
• How often it is missed. Adult cases diagnosed only after years of psychiatric and neurological treatment raise the question of how many cases go unrecognised (Bachmann 2024; Colijn 2025).

Key Research Papers

1. Baron DN, Dent CE, Harris H, Hart EW, Jepson JB. Hereditary pellagra-like skin rash with temporary cerebellar ataxia, constant renal amino-aciduria, and other bizarre biochemical features. Lancet. 1956;271(6940):421-8. PubMed PMID: 13358233
2. Kleta R, Romeo E, Ristic Z, Ohura T, Stuart C, Arcos-Burgos M, et al. Mutations in SLC6A19, encoding B0AT1, cause Hartnup disorder. Nat Genet. 2004;36(9):999-1002. PubMed PMID: 15286787
3. Seow HF, Bröer S, Bröer A, Bailey CG, Potter SJ, Cavanaugh JA, Rasko JE. Hartnup disorder is caused by mutations in the gene encoding the neutral amino acid transporter SLC6A19. Nat Genet. 2004;36(9):1003-7. PubMed PMID: 15286788
4. Bröer S, Cavanaugh JA, Rasko JE. Neutral amino acid transport in epithelial cells and its malfunction in Hartnup disorder. Biochem Soc Trans. 2005;33(Pt 1):233-6. PubMed PMID: 15667315
5. Bröer S. The role of the neutral amino acid transporter B0AT1 (SLC6A19) in Hartnup disorder and protein nutrition. IUBMB Life. 2009;61(6):591-9. PubMed PMID: 19472175
6. Azmanov DN, Kowalczuk S, Rodgers H, Auray-Blais C, Giguère R, Rasko JE, Bröer S, Cavanaugh JA. Further evidence for allelic heterogeneity in Hartnup disorder. Hum Mutat. 2008;29(10):1217-21. PubMed PMID: 18484095
7. Azmanov DN, Rodgers H, Auray-Blais C, Giguère R, Bailey C, Bröer S, Rasko JE, Cavanaugh JA. Persistence of the common Hartnup disease D173N allele in populations of European origin. Ann Hum Genet. 2007;71(Pt 6):755-61. PubMed PMID: 17555458
8. Wilcken B, Yu JS, Brown DA. Natural history of Hartnup disease. Arch Dis Child. 1977;52(1):38-40. PubMed PMID: 836052
9. Scriver CR, Mahon B, Levy HL, Clow CL, Reade TM, Kronick J, Lemieux B, Laberge C. The Hartnup phenotype: Mendelian transport disorder, multifactorial disease. Am J Hum Genet. 1987;40(5):401-12. PubMed PMID: 3578280
10. Wilcken B, Smith A, Brown DA. Urine screening for aminoacidopathies: is it beneficial? Results of a long-term follow-up of cases detected bny screening one millon babies. J Pediatr. 1980;97(3):492-7. PubMed PMID: 7411317
11. Auray-Blais C, Cyr D, Drouin R. Quebec neonatal mass urinary screening programme: from micromolecules to macromolecules. J Inherit Metab Dis. 2007;30(4):515-21. PubMed PMID: 17570073
12. Mahon BE, Levy HL. Maternal Hartnup disorder. Am J Med Genet. 1986;24(3):513-8. PubMed PMID: 3728570
13. Haijes HA, Prinsen HCMT, de Sain-van der Velden MGM, Verhoeven-Duif NM, van Hasselt PM, Jans JJM. Accurate discrimination of Hartnup disorder from other aminoacidurias using a diagnostic ratio. Mol Genet Metab Rep. 2020;22:100551. PubMed PMID: 31908951
14. Bachmann T, Faust H, Abou Jamra R, Pott C, Kluge M, Rumpf JJ, Then Bergh F, Beblo S. Adult Neuropsychiatric Manifestation of Hartnup Disease With a Novel SLCA6A19 Variant: A Case Report. Neurol Genet. 2024;10(6):e200195. PubMed PMID: 39611136
15. Wang X, Li XY, Piao Y, Yuan G, Lin Y, Chen H, Wang Z, Li C, Wang C. Hartnup disease presenting as hereditary spastic paraplegia and severe peripheral neuropathy. Am J Med Genet A. 2022;188(1):237-242. PubMed PMID: 34459558
16. Cheon CK, Lee BH, Ko JM, Kim HJ, Yoo HW. Novel mutation in SLC6A19 causing late-onset seizures in Hartnup disorder. Pediatr Neurol. 2010;42(5):369-71. PubMed PMID: 20399395
17. Zhu Y, Chen L, He J, Chen Y, Gou H, Ma L, Qu Y, Liu Y, Wang D, Zhu Y. Study of Seizure-Manifested Hartnup Disorder Case Induced By Novel Mutations in SLC6A19. Open Life Sci. 2018;13:22-27. PubMed PMID: 33817063
18. Darras BT, Ampola MG, Dietz WH, Gilmore HE. Intermittent dystonia in Hartnup disease. Pediatr Neurol. 1989;5(2):118-20. PubMed PMID: 2712944
19. Tahmoush AJ, Alpers DH, Feigin RD, Armbrustmacher V, Prensky AL. Hartnup disease. Clinical, pathological, and biochemical observations. Arch Neurol. 1976;33(12):797-807. PubMed PMID: 999542
20. Pillai NR, Yubero D, Shayota BJ, Oyarzábal A, Ghosh R, Sun Q, et al. Loss of CLTRN function produces a neuropsychiatric disorder and a biochemical phenotype that mimics Hartnup disease. Am J Med Genet A. 2019;179(12):2459-2468. PubMed PMID: 31520464
21. Ciecierega T, Dweikat I, Awar M, Shahrour M, Libdeh BA, Sultan M. Severe persistent unremitting dermatitis, chronic diarrhea and hypoalbuminemia in a child; Hartnup disease in setting of celiac disease. BMC Pediatr. 2014;14:311. PubMed PMID: 25526748
22. Sander CS, Hertecant J, Abdulrazzaq YM, Berger TG. Severe exfoliative erythema of malnutrition in a child with coexisting coeliac and Hartnup's disease. Clin Exp Dermatol. 2009;34(2):178-82. PubMed PMID: 19018792
23. Seyhan ME, Selimoğlu MA, Ertekin V, Fidanoğlu O, Altinkaynak S. Acrodermatitis enteropathica-like eruptions in a child with Hartnup disease. Pediatr Dermatol. 2006;23(3):262-5. PubMed PMID: 16780476
24. Orbak Z, Ertekin V, Selimoglu A, Yilmaz N, Tan H, Konak M. Hartnup disease masked by kwashiorkor. J Health Popul Nutr. 2010;28(4):413-5. PubMed PMID: 20824986
25. Patel AB, Prabhu AS. Hartnup disease. Indian J Dermatol. 2008;53(1):31-2. PubMed PMID: 19967017
26. Nisoli E, Cinti S, Valerio A. COVID-19 and Hartnup disease: an affair of intestinal amino acid malabsorption. Eat Weight Disord. 2021;26(5):1647-1651. PubMed PMID: 32691334
27. Kraut JA, Sachs G. Hartnup disorder: unraveling the mystery. Trends Pharmacol Sci. 2005;26(2):53-5. PubMed PMID: 15681018
28. Kravetz Z, Schmidt-Kastner R. New aspects for the brain in Hartnup disease based on mining of high-resolution cellular mRNA expression data for SLC6A19. IBRO Neurosci Rep. 2023;14:393-397. PubMed PMID: 37101820
29. Hashmi MS, Gupta V. Hartnup Disease. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. PubMed PMID: 32644502
30. Colijn MA. Hartnup Disease-Associated Psychosis: A Dwindling Phenomenon or Just Underreported? J Acad Consult Liaison Psychiatry. 2025;66(3):272-274. PubMed PMID: 39892832
31. [No authors listed]. Use of ethyl esters of tryptophan to bypass the absorption defect in Hartnup disease. Nutr Rev. 1990;48(1):22-4. PubMed PMID: 2336209

PubMed Topic Searches

1. PubMed: Hartnup disease and SLC6A19
2. PubMed: Hartnup disorder and newborn screening
3. PubMed: Hartnup disease and niacin
4. PubMed: Hartnup disease, ACE2 and COVID-19
5. PubMed: Hartnup disease and psychiatric symptoms

Connections

• Genetics
• Tryptophan and Niacin Synthesis
• Tryptophan
• Pellagra: The Disease of the Four D's
• Niacin Deficiency (Pellagra)
• Phenylketonuria
• Maple Syrup Urine Disease
• Cystinuria

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