DNA haplotype analyses of patients with hyperphenylalaninemia.

Linkage analysis of phenylketonurics has shown a strong association between the DNA haplotype at the phenylalanine hydroxylase (PAH) locus and phenylketonuria (PKU). Similarly, a genetic linkage between less severe forms of hyperphenylalaninemia (HPA) and the PAH locus has been suggested. In the present study we analyzed this linkage in more detail. Haplotypes at the PAH locus were determined for 19 individuals with moderately elevated plasma phenylalanine and normal urinary neopterin/biopterin ratios. Fourteen of these individuals had plasma phenylalanine levels of 4-10 mg/dl (mild HPA), and the other five had plasma phenylalanine levels of 10-19 mg/dl (atypical PKU). Thirteen of the 15 HPA families consisted of an affected child and at least one other sibling. Elevated plasma phenylalanine was seen to genetically segregate with specific PAH alleles in each family. Summation of the LOD scores for both categories of moderate plasma phenylalanine elevation gave a maximum value of 3.556 at theta = 0. At theta = 0 this gives a probability of linkage between the PAH locus and the locus for moderate phenylalanine elevations that is approximately 3,600:1. None of the alleles segregating with either mild HPA or atypical PKU were of haplotype 2 or 3, and 13/20 were of types 1 or 4. This is in agreement with the most deleterious mutations being on haplotypes 2 and 3 and with the less severe mutations being on haplotypes 1 and 4. chi 2 Analyses indicated no statistically significant correlation between HPA and a particular haplotype or restriction-enzyme site.     

Novel PKU mutation on haplotype 2 in French-Canadians.

We analyzed DNA from nine French-Canadian probands from eastern Quebec province; all had hyperphenylalaninemia (phenylketonuria [PKU] or non-PKU forms) caused by mutations at the phenylalanine hydroxylase locus. Analysis of RFLP haplotypes and mutations revealed a novel mutation, an A-to-G transition (met----val) in codon 1 (the translation-initiation codon). It occurred on 5 of the 18 mutant chromosomes and was associated each time with haplotype 2. A proband homozygous for this mutation had the PKU phenotype. In other probands, the codon 1 mutation was inherited once with the splice junction mutation in exon 12 (on haplotype 3), conferring PKU, and was inherited twice with a mutation on haplotype 1, conferring PKU in one proband and non-PKU hyperphenylalaninemia in the other. The other five probands carried mutations, conferring PKU, on the following haplotype combinations: 1/3 (twice), 1/9, 3/4, and 1/1. The mutations on haplotypes 1, 4, and 9 are not yet characterized. This preliminary study reveals a novel PKU mutation and considerable genetic heterogeneity at the phenylalanine hydroxylase locus in French-Canadians.     

Phenylketonuria in Iranian population: a study in institutions for mentally retarded in Isfahan

Phenylalanine hydroxylase (PAH) deficiency is caused by mutations in the PAH gene (12q22-q24) resulting in a primary deficiency of the PAH enzyme activity, intolerance to the dietary intake of phenylalanine (Phe) and production of the phenylketonuria (PKU) disease. To date there have been no reports on the molecular analysis of PKU in Iranian population. In this study, the states of the PKU disease in terms of prevalence and mutation spectrum among patients reside in the institutions for mentally retarded in Isfahan was investigated. In the first step, 611 out of 1541 patients with PKU phenotype or severe mental retardation were screened for the PKU disease using the Guthrie bacterial inhibition assay (GBIA) followed by HPLC. Among the patients screened 34 (5.56%) were found positive with abnormal serum Phe of above 7mg/dl. In the next step, the presence of 18 common mutations of the PAH gene in 26 of the patients with classical PKU (serum Phe above 20mg/dl) was investigated, using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Of the 52 independent mutant alleles that were analyzed, 34 (65.38%) were genotyped showing 8 mutations as follows: R252W (15.38%), Q232Q (13.46%), R261Q (7.69%), delL364 (7.69%), IVS10-11g>a (5.77%), L333F (5.77%), V245V (5.77%) and S67P (3.85%). The results from this study may serve as a reference to analyze the PKU mutations in other part of Iran, and to establish diagnostic tests for carrier detection and prenatal diagnosis of the PKU disease in Iranian population.     

Phenylalanine metabolites as indicators of dietary compliance in children with phenylketonuria

The data from this study showed that the excretion of three major metabolites of phenylalanine in patients with PKU approach normal values at blood phenylalanine levels less than 5.0 mg/dl. The MANOVA showed statistically significant differences in phenyllactate excretion when blood phenylalanine was greater than 10.0 mg/dl. The PL and total metabolite excretion were significantly correlated to blood phenylalanine in multiple samples taken from two individual subjects. Using data obtained from single patient observations may serve as a means for individualizing the PKU diet to insure low levels of phenylalanine metabolites and thus insure optimal development for patients with PKU.     

Rapid mutation screening of phenylketonuria by polymerase chain reaction-linked restriction enzyme assay and direct sequence of the phenylalanine hydroxylase gene: clinical application in northern Japan and northern China

We describe a simple and technically feasible method for mutation screening of the phenylalanine hydroxylase (PAH) gene and its application to Japanese and Chinese patients with hyperphenylalaninemia. The strategy is based on the identification of a nucleotide substitution by restriction enzyme analysis, coupled with PCR and direct sequencing of exon 7 of the PAH gene. Because the detection of various mutations can proceed simultaneously using the same technique, it is quite rapid and reproducible, making it possible to perform effective molecular diagnosis and carrier screening in most laboratories. Using this procedure, we found that the most common molecular defects were R413P in Hokkaido, Japan (35 %) and R243Q in Heilongjiang, China (50%). R111X, IVS4nt-1, and five mutations in exon 7 (R241C, R243Q, R252W, A259T, and S273P) accounted for 55% of phenylketonuria (PKU) alleles in Hokkaido. In Heilongjiang, the R111X, Y356X, and R408W mutations accounted for 35% of PKU alleles. Clinically, homozygotes or compound heterozygotes of null alleles, which express nonfunctional enzyme activity, were all associated with classic PKU. On the other hand, patients heterozygous for the R241C allele had a benign phenotype of mild hyperphenylalaninemia. The DNA diagnosis in early infancy can predict various PKU phenotypes, and can prove useful in decision-making concerning dietary therapy.     

Serum cholesterol and triglyceride measurements in Canadian physicians.

In a study of serum cholesterol and triglyceride concentrations in male physicians, blood was drawn after fasting from 2071 registrants at 17 Canadian medical meetings from 1968 to 1973. Eight regional medical laboratories participated in the study. About two thirds of the samples were analysed in one of two laboratories to diminish method variations. When chylomicronemia, hyperglycemia or extremely high triglyceride values were detected, suggesting nonfasting, the data were discarded. The mean serum cholesterol value for the total study population was 233.9 plus or minus 1.22 mg/dl and the mean serum triglyceride value, 150.5 plus or minus 2.48 mg/dl. The mean values and the prevalence of elevated values (cholesterol larger than or equal to 250 mg/dl; triglyceride larger than or equal to 150 mg/dl) were related to age. Of the total study population 34.7% had elevated cholesterol values and 36.2% had elevated triglyceride values; only the cholesterol value was elevated in 17.5%, only the triglyceride value in 19.6% and both values were elevated in 16.8%. Although this was not a random sampling of Canadian physicians or of Canadian men, our findings of elevated serum lipid values were similar to those in French Canadian civic workers, American executives and Scandinavians, and somewhat higher than those in the Albany, New York and Framingham populations, but distinctly higher than those reported by a recent Nutrition Canada survey.     

Association of low plasma high density lipoprotein (HDL)-cholesterol concentration with documented coronary artery disease in males with non-insulin dependent diabetes mellitus

Plasma lipid and lipoprotein concentrations were determined in 30 males without diabetes or symptomatic coronary artery disease (CAD), and compared to the values in age-matched and weight-matched males (n = 55) with non-insulin-dependent diabetes mellitus (NIDDM). Patients with NIDDM were further subdivided into those with (n = 30) and without (n =25) CAD. Mean (+/- SEM) plasma triglyceride concentrations were significantly increased (P less than 0.001) over control values (96 +/- 5 mg/dl) in patients with NIDDM, whether with (172 +/- 14 mg/dl) or without documented CAD (164 +/- 25 mg/dl). Plasma cholesterol concentrations were also higher (P less than 0.001) than normal (168 +/- 5 mg/dl) in both groups of patients with NIDDM (201 +/- 11 and 199 +/- 7 mg/dl, respectively, in patients with and without evidence of CAD). Plasma LDL-cholesterol concentrations were also greater (P less than 0.001) than normal (104 +/- 4 mg/dl) in patients with NIDDM, but were again similar in the group of diabetics (120 +/- 9 vs 128 +/- 6 mg/dl). However, plasma HDL-cholesterol concentrations were only reduced below control values in diabetes patients with CAD (30 +/- 1 mg/dl), whereas patients with NIDDM and no subjective evidence of CAD had HDL-cholesterol concentrations (37 +/- 3 mg/dl) which were similar to normal values (38 +/- 2 mg/dl). As a result, the ratio of LDL-cholesterol to HDL-cholesterol was highest in patients with NIDDM and CAD (4.2 +/- 0.3), lowest in the control population (2.8 +/- 0.2), and intermediate in those patients with NIDDM without subjective or objective evidence of CAD (3.6 +/- 0.3).(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors predicting the course of diabetes mellitus in hyperthyroid patients

The relationship between changes in glucose tolerance with treatment of hyperthyroidism and various factors that might be relevant to carbohydrate metabolism were investigated in 64 hyperthyroid patients with abnormal glucose tolerance, including 35 cases with fasting plasma glucose (FPG) levels of 140 mg/dl or more. All patients had diffuse toxic goiter. After correction of the hyperthyroidism, glucose intolerance improved in almost all cases, even in cases with fasting hyperglycemia, but diabetes mellitus in patients with FPG above 140 mg/dl and/or delta IRI/delta PG X 30' during a 50-g oral glucose tolerance test below 0.10, persisted. Patients who showed diabetic glucose tolerance even after remission from thyroid dysfunction had significantly lower delta IRI/delta PG X 30' values and a higher incidence of family histories of diabetes mellitus than those not showing diabetic glucose tolerance. There were no significant differences in serum T3 and T4 levels between these two groups of patients. The findings suggest that predisposition to diabetes may be an important factor in persistent glucose intolerance in the hyperthyroidism of Graves' disease. The FPG and delta IRI/delta PG X 30' values may be useful in predicting which patients with hyperthyroidism will have permanent diabetes.     

The phenylketonuria locus: current knowledge about alleles and mutations of the phenylalanine hydroxylase gene in various populations

Summary The hyperphenylalaninemic disorders of classic phenylketonuria (PKU), mild phenylketonuria, and hyperphenylalaninemia (HPA), result from a deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH) or its cofactor (tetrahydrobiopterin). Use of the complementary DNA of this enzyme has allowed the establishment of a restriction fragment length polymorphism (RFLP) haplotype-analysis system. This haplotype analysis system provides the means for determination of mutant PAH alleles in most affected families and is the basis for mutational analysis of the PKU locus. This review is focused on two major areas of current PKU research: (1) the use of DNA haplotype analysis in the study of the population genetics of PAH deficiency, and (2) the study of genotypes, and their various combinations, as a means of explaining and predicting the phenotypic variability observed for the disorders of PAH deficiency.     

Phenylalanine hydroxylase gene mutations in the United States: report from the Maternal PKU Collaborative Study.

The major cause of hyperphenylalaninemia is mutations in the gene encoding phenylalanine hydroxylase (PAH). The known mutations have been identified primarily in European patients. The purpose of this study was to determine the spectrum of mutations responsible for PAH deficiency in the United States. One hundred forty-nine patients enrolled in the Maternal PKU Collaborative Study were subjects for clinical and molecular investigations. PAH gene mutations associated with phenylketonuria (PKU) or mild hyperphenylalaninemia (MHP) were identified on 279 of 294 independent mutant chromosomes, a diagnostic efficiency of 95%. The spectrum is composed of 71 different mutations, including 47 missense mutations, 11 splice mutations, 5 nonsense mutations, and 8 microdeletions. Sixteen previously unreported mutations were identified. Among the novel mutations, five were found in patients with MHP, and the remainder were found in patients with PKU. The most common mutations were R408W, IVS12nt1g-->a, and Y414C, accounting for 18.7%, 7.8%, and 5.4% of the mutant chromosomes, respectively. Thirteen mutations had relative frequencies of 1%-5%, and 55 mutations each had frequencies < or = 1%. The mutational spectrum corresponded to that observed for the European ancestry of the U.S. population. To evaluate the extent of allelic variation at the PAH locus within the United States in comparison with other populations, we used allele frequencies to calculate the homozygosity for 11 populations where >90% ascertainment of mutations has been obtained. The United States was shown to contain one of the most heterogeneous populations, with homozygosity values similar to Sicily and ethnically mixed sample populations in Europe. The extent of allelic heterogeneity must be a major determining factor in the choice of mutation-detection methodology for molecular diagnosis in PAH deficiency.     

Association between minihaplotypes and mutations at the PAH locus in Polish hyperphenylalaninemic patients

Hereditary hyperphenylalaninemia (HPA) is a disorder of amino acid metabolism and results from an insufficiency of hepatic phenylalanine hydroxylase (PAH). HPA phenotypes form a spectrum ranging from classical phenylketonuria (PKU) to mild hyperphenylalaninemia (MHP). The phenotypic diversity reflects heterogeneity at the molecular level, and more than 320 different mutations in the PAH gene are known to date. The association of 3 mutations (R408W, IVS10 and A403V) common in different European populations with a variable number tandem repeat (VNTR) and short tandem repeat sites (minihaplotype) in the PAH gene was examined in a group of Polish PKU and MHP patients. Additionally, minihaplotypes were established for another 16 mutations. The presented data support the hypothesis that the R408W/VNTR3/STR238 allele originated among pre-Indo-Europeans on the territory in present-day Lithuania and Belarus. Mutation IVS10nt-11g-->a (IVS10) is strongly associated with VNTR7/STR250 minihaplotype and is possibly of Mediterranean origin.     

Polymorphic DNA haplotypes at the phenylalanine hydroxylase locus and their relation to phenotype in Swedish phenylketonuria families

Summary The genetic heterogeneity at the phenylalanine hydroxylase (PAH) locus was studied in 88 families including 93 of the 105 children with phenylketonuria (PKU) or hyperphenylalaninemia (HPA) detected through the Swedish neonatal screening program from 1966 to the end of 1986. Haplotypes based on eight restriction fragment length polymorphisms (RFLPs) at the PAH locus could be constructed for 132 normal and 136 mutant alleles. The normal alleles were of 27 different RFLP haplotypes, 9 of which have not been described previously, but there was a dominance of a few haplotypes common to many European populations. The distribution of mutant alleles was significantly different from that in neighboring countries, even though over 90% of all mutant alleles were confined to six RFLP haplotypes, also prevalent in other European populations. Allele-specific oligonucleotide hybridization analysis for the Arg⁴⁰⁸ to Trp⁴⁰⁸ mutation and for the G to A splicing mutation in intron 12 showed exceptions to the previously reported linkage of these mutations to mutant haplotypes 2 and 3, respectively. Correlation of mutant alleles with clinical phenotypes pointed to the presence of at least two different mutations associated with each of six haplotypes. We argue that PKU/HPA in the Swedish population may be caused by at least 13 different mutations in addition to the 4 already identified. The theoretical informativity of RFLP analysis in heterozygote detection and prenatal diagnosis in PKU/HPA families was estimated at approximately 85%. Carrier detection could, in effect, be accomplished for 88% of the 56 healthy siblings in the families studied.     

A new experimental model of hyperphenylalaninemia in rat. Effect of p-chlorophenylalanine and cotrimoxazole.

A new experimental model of hyperphenylalaninemia was proposed. Combination of p.chlorophenylalanine, strongly inhibitor of phenylalanine hydroxylase, and cotrimoxazole, presumably inhibitor of dihydropteridine reductase, produced a good inhibition of phenylalanine hydroxylation in vivo. Thus phenylalaninemia reached values similar to those found in PKU patients, without administration of excess phenylalanine. Tyrosine concentrations remained near the control values and a phenylketonuria occurred.     

Phenylketonuria and its variants: observations on intellectual functioning.

The age at diagnosis, dietary treatment and intelligence quotient (IQ) of 119 patients with phenylketonuria (PKU) and its variants who were under long-term observation were studied. In 27 of the 79 patients with classic PKU the diagnosis had been made and treatment begun late (after 2 months of age). The mean IQ of these 27 patients was 57.6 when they were in their early 20s (although 2 had normal IQs). In contrast, among the 52 patients with classic PKU who were not treated late the mean IQ was 93.6 for the 27 who were still receiving dietary therapy. The mean IQs were 99.3 and 92.7 at ages 5 (when the diet was discontinued) and 15 years respectively for the 12 who had been treated "adequately". It was 76.0 for the 13 who were "over-treated" (malnourished) in the first 6 months of life. Among the patients with atypical PKU, who were treated early, the mean IQs were 110.0 for the 7 who were still receiving dietary therapy and 102.7 for the 12 who were not. The 21 patients with persistent benign hyperphenylalaninemia, who were not treated, had a mean IQ of 104.2. The most important factor in the ultimate IQ of patients with classic PKU is very early diagnosis (by 2 weeks of age) along with immediate initiation of dietary therapy.     

Mutational landscape of phenylketonuria in Iran

To date more than 1000 different variants in the PAH gene have been identified in patients with phenylketonuria (PKU). In Iran, several studies have been performed to investigate the genetics bases of the PKU in different parts of the country. In this study, we have analysed and present an update of the mutational landscape of the PAH gene as well as the population genetics and frequencies of detected variants for each cohort. Published articles on PKU mutations in Iran were identified through a comprehensive PubMed, Google Scholar, Web of Science (ISI), SCOPUS, Elsevier, Wiley Online Library and SID literature search using the terms: “phenylketonuria”, “hyperphenylalaninemia”, and “PKU” in combination with “Iran”, “Iranian population”, “mutation analysis”, and “Molecular genetics”. Among the literature-related to genetics of PKU, 18 studies were on the PKU mutations. According to these studies, in different populations of Iran 1497 patients were included for mutation detection that resulted in detection of 129 different mutations. Results of genetic analysis of the different cohorts of Iranian PKU patients show that the most prevalent mutation in Iran is the pathogenic splice variant c.1066-11G > A, occurring in 19.54% of alleles in the cohort. Four other common mutations were p.Arg261Gln, p.Pro281Leu, c.168 + 5G > C and p.Arg243Ter (8.18%, 6.45%, 5.88% and 3.7%, respectively). One notable feature of the studied populations is its high rate of consanguineous marriages. Considering this feature, determining the prevalent PKU mutations could be advantageous for designing screening and diagnostic panels in Iran.     

LDL-C calculated by Friedewald,Martin-Hopkins,or NIH equation 2 versus beta-quantification: pooled alirocumab trials

Accurate assessment of LDL-C levels is important, as they are often used for treatment recommendations. For many years, plasma LDL-C levels were calculated using the Friedewald equation, but there are limitations to this method compared with direct measurement via beta-quantification (BQ). Here, we assessed differences between the Friedewald, Martin-Hopkins, and NIH equation 2 methods of calculating LDL-C and the “gold standard” BQ method using pooled phase 3 data with alirocumab. All randomized patients were included irrespective of the treatment arm (n = 6,122). We compared pairs of LDL-C values (n = 17,077) determined by each equation and BQ. We found that BQ-derived LDL-C values ranged from 1 to 397 mg/dl (mean 90.68 mg/dl). There were strong correlations between Friedewald-calculated, Martin-Hopkins–calculated, and NIH equation 2–calculated LDL-C with BQ-determined LDL-C values (Pearson's correlation coefficient = 0.985, 0.981, and 0.985, respectively). Importantly, for BQ-derived LDL-C values ≥70 mg/dl, only 3.2%, 1.4%, and 1.8% of Friedewald-calculated, Martin-Hopkins–calculated, and NIH equation 2–calculated values were <70 mg/dl, respectively. When triglyceride (TG) levels were <150 mg/dl, differences between calculated and BQ-derived LDL-C values were minimal, regardless of the LDL-C level (<40, <55, or <70 mg/dl). However, when TG levels were >150 mg/dl, NIH equation 2 provided greater accuracy than Friedewald or Martin-Hopkins. When TGs were >250 mg/dl, inaccuracies were seen with all three methods, although NIH equation 2 remained the most accurate. In conclusion, LDL-C calculated by any of the three methods can guide treatment decisions for most patients, including those treated with proprotein convertase subtilisin/kexin type 9 inhibitors.     

Fifteen-year experience with screening for phenylketonuria with an automated fluorometric method.

An automated fluorometric method, rather than the Guthrie test, has been used in North Carolina for neonatal screening for phenylketonuria (PKU). Although there is no testing law, 97% of newborn infants are screened. Twelve children with PkU, not referred for dietary management, were born before the screening program was established, were born elsewhere, or were successfully identified at birth but not referred for treatment. None was missed because of laboratory error or because of the lack of a testing law. Positive skewing was noted among initial blood phenylalanine levels of 49 infants with PKU and severe hyperphenylalaninemia. Log transformations caused the values to be normally distributed and permitted the calculation of tolerance and confidence limits. These provided estimates of the percentage of phenylketonuric infants whose initial blood levels might fall below any given cutoff value.     

TRANSURETHRAL PROSTATECTOMIES—A Review of 560 Cases

Of 560 prostatectomies in an 11-year period on patients with benign or malignant disease of the prostate gland, almost 98 per cent were done transurethrally.Although many of the patients were considered to be in poor condition preoperatively, results achieved by the transurethral operation were excellent or good in 91 per cent of those who had benign disease of the prostate and in 84 per cent of those with malignant invasion. The rate of deaths attributable to the operation was 3.1 per cent in the group of patients with benign disease, 5.3 per cent in patients who had cancer.Complications, such as urinary incontinence, persistent pyuria, epididymitis, strictures of the urethra and of the meatus, and contracture of the neck of the bladder, arose in a surprising number of cases.     

Role of Catalase and Superoxide Dismutase Activities on Oxidative Stress in the Brain of a Phenylketonuria Animal Model and the Effect of Lipoic Acid

Phenylketonuria (PKU) is an inherited metabolic disorder caused by deficiency of phenylalanine hydroxylase which leads to accumulation of phenylalanine and its metabolites in tissues of patients with severe neurological involvement. Recently, many studies in animal models or patients have reported the role of oxidative stress in PKU. In the present work we studied the effect of lipoic acid against oxidative stress in rat brain provoked by an animal model of hyperphenylalaninemia (HPA), induced by repetitive injections of phenylalanine and α-methylphenylalanine (a phenylalanine hydroxylase inhibitor) for 7 days, on some oxidative stress parameters. Lipoic acid prevented alterations on catalase (CAT) and superoxide dismutase (SOD), and the oxidative damage of lipids, proteins, and DNA observed in HPA rats. In addition, lipoic acid diminished reactive species generation compared to HPA group which was positively correlated to SOD/CAT ratio. We also observed that in vitro Phe inhibited CAT activity while phenyllactic and phenylacetic acids stimulated superoxide dismutase activity. These results demonstrate the efficacy of lipoic acid to prevent oxidative stress induced by HPA model in rats. The possible benefits of lipoic acid administration to PKU patients should be considered.     

The spectrum of mutations in the <Emphasis Type="Italic">PAH</Emphasis> gene in patients with hyperphenylalaninemia from the Karachay-Cherkess Republic

According to the neonatal screening conducted during the last nine years in Karachay-Cherkessia, the frequency of hyperphenylalaninemia (including PKU) was 1: 850 newborns, which significantly exceeded the average frequency of 1: 7000 in Russia. Analysis of DNA obtained from 25 patients with a diagnosis of “hyperphenylalaninemia” (HPA) from the Karachay-Cherkess Republic was performed to search for mutations in the PAH gene. Mutations were identified on 90% of the studied chromosomes, while at least one mutation in the PAH gene was observed in all patients. The allele frequency of a major mutation R261X was 32.5%. A correlation between genotype and phenotype was confirmed in patients with HPA.