What is Hartnup disease in biochemistry?

Hartnup disease is a condition caused by the body’s inability to absorb certain protein building blocks (amino acids) from the diet. As a result, affected individuals are not able to use these amino acids to produce other substances, such as vitamins and proteins.

What is the cause of Hartnup disease?

Hartnup disease is caused by alterations (mutations) in the SLC6A19 gene. Genes provide instructions for creating proteins that play a critical role in many functions of the body. When a mutation of a gene occurs, the protein product may be faulty, inefficient, or absent.

How is Hartnup disease treated?

Treatment of Hartnup Disease

  1. Protein and niacin in the diet.
  2. Supplements of nicotinamide (niacinamide) or niacin (nicotinic acid)
  3. For attacks, nicotinamide.
  4. Avoiding sun exposure and sulfonamides.

What are symptoms of Hartnup disease?

What are the symptoms of Hartnup disease?

  • skin rash.
  • anxiety.
  • rapid mood swings.
  • delusions.
  • hallucinations.
  • intention tremor.
  • speech difficulties.
  • unsteady wide-based gait, in which you walk with your legs farther apart than normal.

What is Refsum disease?

Definition. Adult Refsum disease (ARD) is a rare genetic disease that causes weakness or numbness of the hands and feet (peripheral neuropathy). Due to a genetic abnormality, people with ARD disease lack the enzyme in peroxisomes that break down phytanic acid, a type of fat found in certain foods.

Is Refsum disease genetic?

Refsum disease is an autosomal recessive genetic disorder.

Is Refsum disease treatable?

Although there is no cure, phytanate levels in Refsum disease patients can be reduced by plasmapheresis and a strict diet. Pharmacological up-regulation of the omega-oxidation of phytanic acid may form the basis of the new treatment strategy for adult Refsum disease in the near future.

How is Tyrosinemia Type 1 diagnosed?

Molecular genetic testing for FAH gene mutations is available to confirm the diagnosis. Tyrosinemia type I may also be diagnosed through newborn screening programs. Succinylacetone can be measured on the newborn blood spot by tandem mass spectroscopy. Most states in the U.S. screen every newborn for tyrosinemia type 1.

How tyrosinemia is different from PKU?

Transient tyrosinemia of the newborn Most infants are asymptomatic, but some have lethargy and poor feeding. Tyrosinemia is distinguished from PKU by elevated plasma tyrosine levels. Most cases resolve spontaneously.

Which enzyme is responsible for Refsum disease?

A very rare early onset disorder called polyneuropathy (numbness, tingling), hearing loss, ataxia, retinitis pigmentosa, and cataract (PHARC) shares many clinical features with Refsum disease but is caused by a defect in a different enzyme called abhydrolase domain containing 12-Lysophospholipase (ABHD12) which is …

How is Refsum disease treated?

Treatment for Refsum disease is based on limiting the intake of foods high in phytanic acid. Our bodies cannot make phytanic acid; rather, it is found in foods such as dairy, beef, lamb, and some seafoods.

What kind of metabolic disorder is Hartnup disease?

Hartnup disease (also known as ” pellagra -like dermatosis ” and “Hartnup disorder”) is an autosomal recessive metabolic disorder affecting the absorption of nonpolar amino acids (particularly tryptophan that can be, in turn, converted into serotonin, melatonin, and niacin ). Niacin is a precursor to nicotinamide, a necessary component of NAD+.

How does Hartnup disease affect the absorption of amino acids?

The defective gene controls the absorption of certain amino acids from the intestine and the reabsorption of those amino acids in the kidneys. Consequently, a person with Hartnup disease cannot absorb amino acids properly from the intestine and cannot reabsorb them properly from tubules in the kidneys.

What kind of tests are done for Hartnup disease?

With urine chromatography, increased levels of neutral amino acids (e.g., glutamine, valine, phenylalanine, leucine, asparagine, citrulline, isoleucine, threonine, alanine, serine, histidine, tyrosine, tryptophan) and indican are found in the urine. Increased urinary Indican can be tested by Obermayer test.

How is Hartnup disease related to low nicotinamide?

Pellagra, a similar condition, is also caused by low nicotinamide; this disorder results in dermatitis, diarrhea, and dementia. 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.