Protein, intolerance

OTC deficiency must be suspected in any patient, male or female, with unexplained neurological symptoms. The absence of hyperammonemia should not rule out the diagnosis, especially with a history of protein intolerance, a suggestive family history or an untoward reaction... 

Lysinuric protein intolerance. Infants manifest growth failure, hepatosplenomegaly, vomiting, hypotonia, recurrent lethargy, coma, abdominal pain and, in rare instances,... 

Table 2.1.9 Changes of blood amino acids in various primary inherited defects and as a result of secondary changes. ASA Argininosuccinic acid, CPS carbamoyl phosphate synthase, LPI Lysinuric protein intolerance, MAD multiple acyl-CoA dehydrogenation, MSUD maple syrup urine disease, NAGS N-acetylglutamate synthase, NKH nonketotic hyperglycinemia, NTBC 2-(2-nitro-4-3 trifluoro-methylbenzoyl)-1,3-cyclohexanedione, OCT Ornithine carbamoyltransferase,...

Jakobsson, I. and Lindberg, T. 1979. A prospective study of cow s milk protein intolerance in Swedish infants. Acta Paediatr. Scand. 68, 853-859. 

The disorder is inherited as an autosomal recessive characteristic and it is rare, with fewer than 30 cases so far described. Severely affected infants show symptoms within a few days of birth. A mild or benign form has been reported in adults (G10). Infants with the disorder fail to thrive or grow, they may be mentally retarded, and they have intermittent hypoglycemia or hyperglycemia. Protein intolerance is also a feature, with vomiting and ketosis. 

A number of amino acid transport disorders may be associated with one or several of the systems described in Table 20.4. These are characterized by the excretion of amino acids in the urine but no increase in amino acid levels in the bloodstream. They are usually of hereditary origin. The most common disorder is cystinuria, characterized by the excretion of cystine. Because cystine is only slightly water soluble, cystinuria is often accompanied by the deposition of cystine-containing stones in the genitourinary tract. Cystinuria is apparently caused by a defect in the cationic amino acid transport system. Another disease that affects this system is lysinuric protein intolerance, which is associated with a failure to transport lysine, ornithine, arginine, and citrulline across membranes. Citrulline and ornithine are urea cycle intermediates (see later), and a disruption of their interorgan traffic results in hyperammonemia. 

Propionyl CoA inhibits A(-acetylglutamate synthetase competitively with respect to acetyl CoA, forming A(-propionylglutamate and reducing the synthesis of A(-acetylglutamate. This is an obligatory activator of carbamyl phosphate synthetase, the first enzyme of urea synthesis. Vitamin B12 deficiency may result in some degree of protein intolerance and hyperammonemia. 

C-11) Propionyl CoA carboxylase deficiency. The serum shows elevated propionate. The patient may have mental retardation, ketoacidosis, protein intolerance and other defects. 

Suppression of bowel flora is thought by some to be useful in hepatic encephalopathy. Here, absorption of products of bacterial breakdown of protein (ammonium, amines) in the intestine lead to cerebral symptoms and even to coma. In acute coma, neomycin 6 g/d should be given by gastric tube as prophylaxis, 1-4 g/d may be given to patients with protein intolerance who fail to respond to dietary protein restriction (see also lactulose, p. 640). 

Protein intolerance, organomegaly, osteoporosis, interstitial lung disease, variable mental retardation Ataxia, seizures, photodermatitis (pellagra-like)... 

A syndrome of familial protein intolerance with intermittent mild or moderate hyperammonemia has been described by Perheentupa and his... 

This condition of familial protein intolerance can be differentiated... 

K4. Kekomaki, M. P., Raihk, N. C. R., and Bickel, H., Ornithine ketoacid aminotransferase in human liver with reference to patient with hyperornithinaemia and familial protein intolerance. Clin. Chim. Acta 23, 203-208 (1969). 

K5. Kekomaki, M., Raiha, N. C. R., and Perheentupa, J., Enzymes of urea synthesis in familial protein intolerance with deficient transport of basic amino acids. Acta Paediat. Scand. 66, 631-636 (1967). 

Although clinical data suggest that critically ill neonates will benefit from aggressive PN within the first 24 hours of life, some clinicians withhold PN therapy for 2 to 3 days after birth because of concerns for development of adverse effects associated with protein intolerance, such as hyperammonemia, azotemia, and metabolic acidosis. 

SLC7 Cationic amino acid transporter 14 Melphalan Lysinuric protein intolerance... 

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