Haplotype distribution and molecular defects of PKU in Italy.
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Biomedical subjects
Publications and source records attributed to R Cerone.
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The aim of this collaborative study was to investigate whether guanidino compound analyses in the biologic fluids can be used as a complementary diagnostic parameter for hyperargininemia. Guanidino compounds were determined in the biologic fluids of all known living hyperargininemic patients using a cation exchange chromatographic system with a fluorescence detection method. The serum arginine, homoarginine, alpha-keto-delta-guanidino-valeric acid, argininic acid, and N-alpha-acetylarginine levels of all the hyperargininemic patients are higher than the normal range. Similar increases were seen for the urinary excretion of alpha-keto-delta-guanidinovaleric acid and argininic acid. Untreated hyperargininemic patients have the highest guanidino compound levels in cerebrospinal fluid. However, even under therapy, the arginine, homoarginine, alpha-keto-delta-guanidinovaleric acid, and argininic acid levels in cerebrospinal fluid are still increased. Protein restriction alone is not sufficient to normalize the hyperargininemia, but protein restriction together with supplementation of essential amino acids with or without sodium benzoate decreases further the arginine levels. However, whereas the argininemia can be normalized, the catabolites of arginine are still increased. We conclude that the urinary amino acid levels may remain normal in hyperargininemia, whereas consistent increases of the guanidino compounds are observed. Thus, guanidino compound analyses can be used as a complementary biochemical diagnostic parameter for hyperargininemia. Although the argininemia can be normalized by therapy, the levels of the catabolites of arginine are still elevated.
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An international questionnaire survey has been conducted to define better the natural history of homocystinuria due to cystathionine beta-synthase deficiency and permit evaluation of treatment. Data were compiled for 629 patients. Among patients not discovered by newborn screening, B6-responsive individuals on the average have significantly better mental capabilities (mean IQ, 79) than do B6-nonresponsive individuals (mean IQ, 57). Time-to-event curves are presented for the other major clinical abnormalities produced by this disease. Each occurred at significantly lower rates in untreated B6-responsive than in untreated B6-nonresponsive patients, as shown by the following examples: (1) dislocation of optic lenses (at age 10, chances of dislocation: 55% and 82%, respectively); (2) initial clinically detected thromboembolic events (at age 15, chances of having had such an event: 12% and 27%, respectively); (3) radiologic detection of spinal osteoporosis (at age 15, chances of such osteoporosis having been detected: 36% and 64%, respectively); and (4) mortality (at age 30, chances of not surviving: 4% and 23%, respectively). Methionine restriction initiated neonatally prevented mental retardation, retarded the rate of lens dislocation, and may have reduced the incidence of seizures. Pyridoxine treatment of late-detected B6-responsive patients retarded the rate of occurrence of initial thromboembolic events. Following 586 surgical procedures, 25 postoperative thromboembolic complications occurred, six of which were fatal. Reproductive histories were reported predominantly for B6-responsive patients. Living offspring of either men or women patients had few abnormalities. The evidence is inconclusive whether untreated maternal cystathionine beta-synthase deficiency leads to excessive fetal loss. Only 13% of patients detected in screening programs of newborns and classified as to B6-responsiveness were B6-responsive, compared to 47% among late-detected patients. Current screening programs that identify neonatal hypermethioninemia may be preferentially failing to detect B6-responsive patients.
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As already described for cystic fibrosis and Friedreich ataxia, the incidence of PKU in Italy has been estimated by determining the increase of consanguineous marriages among 178 couples of PKU parents over the frequencies carefully established for the same marriages in the general Italian population for each of the 95 provinces during a 55-year period. The incidence estimated (between 1/15595 and 1/17815 according to two different formulas) is not very different from the incidence derived from screening programs (almost 1/12000). This indicates that the former method can be applied in Italy to the study of the incidence of other autosomal recessive disorders.
Five females with duplication of the short arm of one chromosome 9 are reported, one tetrasomic and four trisomic for 9p. The tetrasomy is due to an isochromosome 9p while the trisomies are due in one case to an intrachromosomal duplication present in lymphocytes but not in fibroblasts, two are secondary to translocations with chromosomes 22 and 13 respectively, and one is a mosaic with a cell line with an additional deleted chromosome 9 present in lymphocytes and fibroblasts. This analysis indicates that duplications 9p may result in impairment of ovarian function. The phenotypic differences between trisomy and tetrasomy 9p are discussed.
Maple Syrup Urine Disease (MSUD) is an inherited metabolic disorder characterized by a severe, usually lethal, neonatal course in the early stages with pseudotumor cerebri and pathologically documented increased cerebral water content. CT and MRI studies in MSUD are few and the data are overlapping. This study reports CT features before and after dietary treatment in three patients; two with classical MSUD and one with an intermediate variant of MSUD. At diagnosis, CT consistently showed evidence of abnormally high lucidity involving not only white matter, but also areas of grey matter, particularly the pallidum. Furthermore, these CT changes are present both in the acute phase of classical MSUD and in an intermediate variant of the disease. The observed abnormalities evolve favorably under dietary treatment, simultaneously with clinical and neurological improvement. It is concluded that the observed CT changes indicate a diagnosis of MSUD and are relevant findings in the neuroradiologic differential diagnosis in acutely ill newborns, in which a metabolic disease may be not immediately suspected.
BACKGROUND: To assess the acceptability and nutritional adequacy of a new phenylalanine-free amino acid mixture (Phenylade-Dietetic Metabolic Food). METHODS: Twenty PKU patients (aged 2.6-10 years) diagnosed and followed by our Department. The children were given this product for a minimum of 4 and a maximum of 12 months. The clinical control has been carried out before treatment and then every 3 months. The biochemical parameters included: quantitative plasma amino acids, hematologic measurements of nutritional adequacy folic acid and vitamin B12. RESULTS: All patients (except one) found this new product to be an acceptable alternatives as to taste and convenience to the previous low phenylalanine protein substitutes. CONCLUSIONS: Normal growth was maintained.
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Plasma protein and amino acid concentrations have been reported to be abnormal in patients with chronic renal failure, whether on conservative or regular dialysis treatment. These abnormalities may be related to impaired protein and amino acid metabolism associated with uremia, to dietary deficiencies of calories and proteins or to amino acid and protein losses due to peritoneal dialysis or hemodialysis. Plasma free amino acid concentrations were evaluated in 17 children undergoing hemodialysis (HD) and 13 children treated by continuous ambulatory peritoneal dialysis (CAPD). Plasma levels of free amino acids showed a reduction of EAA and of the ratio EAA/NEAA. There were some abnormalities in plasma amino acid concentrations; these included decreased levels of valine, threonine, lysine, serine, tyrosine, arginine, alpha-ABA. Aspartate, glycine, citrulline, and, only in HD, cystine and methionine were increased. Plasma protein and amino acid concentrations in CAPD patients are similar to those found in HD patients; thus they result poorly affected by different dialysis techniques and the uremic state itself seems to play a more decisive role.