Lysinuric protein intolerance

Lysinuric protein intolerance
Lysine
Classification and external resources
Specialty	endocrinology
ICD-10	E72.3
OMIM	222700
DiseasesDB	29819
GeneReviews	Lysinuric Protein Intolerance

Lysinuric protein intolerance (LPI), also called hyperdibasic aminoaciduria type 2,cationic aminoaciduria or familial protein intolerance, is an autosomal recessive^[1] metabolic disorder affecting amino acid transport.

About 140 patients have been reported, almost half of them of Finnish origin. Individuals from Japan, Italy, Morocco and North Africa have also been reported.

Causes

It has been associated with SLC7A7.^[2]

Presentation

Lysinuric protein intolerance has an autosomal recessive pattern of inheritance.

In LPI, urinary excretion of cationic amino acids (ornithine, arginine and lysine) is increased and these amino acids are poorly absorbed from the intestine. Therefore, their plasma concentrations are low and their body pools become depleted. Deficiency of arginine and ornithine restricts the function of the urea cycle and leads to hyperammonemia after protein-rich meals. Deficiency of lysine may play a major role in the skeletal and immunological abnormalities observed in LPI patients.

Diagnosis

The diagnosis is based on the biochemical findings (increased concentrations of lysine, arginine and ornithine in urine and low concentrations of these amino acids in plasma, elevation of urinary orotic acid excretion after protein-rich meals, and inappropriately high concentrations of serum ferritin and lactate dehydrogenase isoenzymes) and the screening of known mutations of the causative gene from a DNA sample.

Symptoms

Infants with LPI are usually symptom-free when breastfed because of the low protein concentration in human milk, but develop vomiting and diarrhea after weaning. The patients show failure to thrive, poor appetite, growth retardation, enlarged liver and spleen, prominent osteoporosis and osteopenia,^[3] delayed bone age and spontaneous protein aversion. Forced feeding of protein may lead to convulsions and coma. Mental development is normal if prolonged episode of hyperammonemia can be avoided. Some patients develop severe pulmonary and renal complications. High levels of plasma glutamine and glycine are observed.

Treatment and prognosis

Treatment of LPI consists of protein-restricted diet and supplementation with oral citrulline. Citrulline is a neutral amino acid that improves the function of the urea cycle and allows sufficient protein intake without hyperammonemia. Under proper dietary control and supplementation, the majority of the LPI patients are able to have a nearly normal life. However, severe complications including pulmonary alveolar proteinosis and renal insufficiency may develop even with proper treatment. ^[4]

Fertility appears to be normal in women, but mothers with LPI have an increased risk for complications during pregnancy and delivery. ^[5]

References

↑ Simell O, Perheentupa J, Rapola J, Visakorpi JK, Eskelin LE (August 1975). "Lysinuric protein intolerance" (Free full text). The American Journal of Medicine 59 (2): 229–240. doi:10.1016/0002-9343(75)90358-7. PMID 1155480.
↑ Borsani G, Bassi MT, Sperandeo MP, et al. (March 1999). "SLC7A7, encoding a putative permease-related protein, is mutated in patients with lysinuric protein intolerance". Nat. Genet. 21 (3): 297–301. doi:10.1038/6815. PMID 10080183.
↑ Online 'Mendelian Inheritance in Man' (OMIM) 222700
↑ Tanner LM, Näntö-Salonen K, Niinikoski H, et al. (June 2007). "Nephropathy advancing to end-stage renal disease: a novel complication of lysinuric protein intolerance". J Pediatr. 150 (6): 161–164. doi:10.1016/j.jpeds.2007.01.043. PMID 17517249.
↑ Tanner LM, Näntö-Salonen K, Niinikoski H, et al. (February 2006). "Hazards associated with pregnancies and deliveries in lysinuric protein intolerance". Metabolism 55 (2): 224–231. doi:10.1016/j.metabol.2005.08.016. PMID 16423630.

External links

GeneReview/NIH/UW entry on Lysinuric Protein Intolerance

Inborn error of amino acid metabolism (E70–E72, 270)

K→acetyl-CoA

Lysine/straight chain	Glutaric acidemia type 1 type 2 Hyperlysinemia Pipecolic acidemia Saccharopinuria

Leucine	3-hydroxy-3-methylglutaryl-CoA lyase deficiency 3-Methylcrotonyl-CoA carboxylase deficiency 3-Methylglutaconic aciduria 1 Isovaleric acidemia Maple syrup urine disease

Tryptophan	Hypertryptophanemia

G→pyruvate→citrate

Glycine	D-Glyceric acidemia Glutathione synthetase deficiency Sarcosinemia Glycine→Creatine: GAMT deficiency Glycine encephalopathy

G→glutamate→
α-ketoglutarate

Histidine	Carnosinemia Histidinemia Urocanic aciduria

Proline	Hyperprolinemia Prolidase deficiency

Glutamate/glutamine	SSADHD

G→propionyl-CoA→
succinyl-CoA

Valine	Hypervalinemia Isobutyryl-CoA dehydrogenase deficiency Maple syrup urine disease

Isoleucine	2-Methylbutyryl-CoA dehydrogenase deficiency Beta-ketothiolase deficiency Maple syrup urine disease

Methionine	Cystathioninuria Homocystinuria Hypermethioninemia

General BC/OA	Methylmalonic acidemia Methylmalonyl-CoA mutase deficiency Propionic acidemia

G→fumarate

Phenylalanine/tyrosine

Phenylketonuria	6-Pyruvoyltetrahydropterin synthase deficiency Tetrahydrobiopterin deficiency

Tyrosinemia	Alkaptonuria/Ochronosis Type I tyrosinemia Type II tyrosinemia Type III tyrosinemia/Hawkinsinuria

Tyrosine→Melanin	Albinism: Ocular albinism (1) Oculocutaneous albinism (Hermansky–Pudlak syndrome) Waardenburg syndrome

Tyrosine→Norepinephrine	Dopamine beta hydroxylase deficiency reverse: Brunner syndrome

G→oxaloacetate

Urea cycle/Hyperammonemia (arginine aspartate)	Argininemia Argininosuccinic aciduria Carbamoyl phosphate synthetase I deficiency Citrullinemia N-Acetylglutamate synthase deficiency Ornithine transcarbamylase deficiency/translocase deficiency

Transport/
IE of RTT

Other

Genetic disorder, membrane: Solute carrier disorders

1-10	SLC1A3 Episodic ataxia 6 SLC2A1 De Vivo disease SLC2A5 Fructose malabsorption SLC2A10 Arterial tortuosity syndrome SLC3A1 Cystinuria SLC4A1 Hereditary spherocytosis 4/Hereditary elliptocytosis 4 SLC4A11 Congenital endothelial dystrophy type 2 Fuchs' dystrophy 4 SLC5A1 Glucose-galactose malabsorption SLC5A2 Renal glycosuria SLC5A5 Thyroid dyshormonogenesis type 1 SLC6A19 Hartnup disease SLC7A7 Lysinuric protein intolerance SLC7A9 Cystinuria

11-20	SLC11A1 Crohn's disease SLC12A3 Gitelman syndrome SLC16A1 HHF7 SLC16A2 Allan–Herndon–Dudley syndrome SLC17A5 Salla disease SLC17A8 DFNA25

21-40	SLC26A2 Multiple epiphyseal dysplasia 4 Achondrogenesis type 1B Recessive multiple epiphyseal dysplasia Atelosteogenesis, type II Diastrophic dysplasia SLC26A4 Pendred syndrome SLC35C1 CDOG 2C SLC39A4 Acrodermatitis enteropathica SLC40A1 African iron overload

see also solute carrier family

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