• Journal of The Korean Society of Inherited Metabolic disease
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• v.13 no.1
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• pp.30-36
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• 2013

6-pyruvoyltetrahydropterin synthase (PTPS) deficiency is autosomal recessive disorder and the most common type of tetrahydrobiopterin (BH4) deficiency. It is caused by deficiency of PTPS, a cofactor involved in the biosynthesis of BH4 from guanosine triphosphate (GTP). Unlike classical phenylketonuria, which needs restriction of dietary phenylalanine for whole life, BH4 deficiency is treated by tetrahydrobiopterin, levodopa, and 5-hydroxytryptophan replacement. So it is important to make accurate diagnosis and initiate treatment as soon as possible for a better prognosis. There is no retrospective study of Korean patients undergoing long-term treatment for PTPS deficiency. We report 9 Korean patients with PTPS deficiency and their laboratory findings including BH4 loading tests, urine pterin tests, genotypes, dihydropteridine reductase (DHPR) activities and clinical manifestations including medication and developmental delay existence.

• Journal of Preventive Medicine and Public Health
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• v.32 no.3
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• pp.317-324
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• 1999

Objectives: Since 1991, nationwide massive neonatal screening program for phenylketonuria (PKU) and congenital hypothyroidism have been performed in Korea. As in many other countries, efficiency of this program has not been definitely concluded. For the purpose of evaluation of this program, from the perspective of efficiency, a cost-benefit analysis was carried out. Methods: Costs of the detection and the treatment program were compared with the projected benefit(avoided costs) that results from the prevention of the mental retardation associated with the disorders due to PKU and hypothyroidism. Costs and benefits were discounted at an annual rate of 5%, and duration of life-long labor was assumed to be 30 years. Cost and benefit were estimated based on the detection rates of one case of PKU per 5,572 and one case of congenital hypothyroidism per 32,554 babies screened during 1991-1997. Results: The benefit-cost ratio was 0.418. The sensitivity analysis for the discount rates and labor durations showed that most cost-benefit ratios were lower than one(1.0) except when discount rate was changed to 3% and detection rate to two- or threefold and/or labor duration to 40 years. Conclusion: The result of this study suggested that present program of mass screening for PKU and congenital hypothyroidism could not be justified in terms of efficiency. It doesn't coincide with the results of previous studies in major developed countries, presumably because of difference in detection rates and welfare cost for the disabled.

• Clinical and Experimental Pediatrics
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• v.49 no.11
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• pp.1125-1139
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• 2006

In 1991, the Ministry of Health & Social affairs adopted a nationwide service program for neonatal screening of phenylketonuria, galactosemia, maple syrup urine disease, homocystinuria, histidinemia & congenital hypothyroidism for newborns delivered from low class pregnant women registered in health centers. Government decreased the test items from six to two, PKU & congenital hypothyroidism to increase test numbers with same budget from 1995. Government decided to test PKU & hypothyroidism for all newborns from 1997. 78 laboratories wanted to participate for neonatal screening test in 1999. Government didn't decide laboratory center for a certain district and placed responsibility on free competition. Government are planning to test 573,000 newborns from 1998, Government decided to screen 6 items PKU, congenital hypothyroidism, maple syrup urine disese, homocystinuria, galactosemia and congenital adrenal hyperplasia from 2006. 17 laboratores are participating now. The cost of screening test is supported by both the federal government and local government on a 40-60 basis. In case a patient with an inherited metabolic disease is diagnosed by screening of government program, special milk is provided at government's expense. Interlaboratory quality control was started 6 times a year from 1994. According to the government project, 3,707,773 newborns were screened. 86 PKU, 718 congenital hypothyroidism were detected. So incidence of PKU is 1/43,114 and congenital hypothyroidism is 1/4,612. Maeil dairy company produced new special formula for PKU, MMA and PA, MSUD, urea cycle disorder, homocystinuria, isovaleric acidemia from Oct. 1999. The cost benefit of performing screening procedures coupled with treatment has been estimated to be as high as 1.77 times in PKU, 11.11 times in congenital hypothyroidism than cost without screening. We are trying to increase the budget to test all newborns for Tandem mass sereening & Wilson disease from 2008. Now it is a very important problem to decrease laboratory numbers of neonatal screening in Korea. So we are considering 4-5 central laboratories which cover all newborns and are equipped with tandem mass spectrometer & enzyme immunoassay for TSH, 17OHP & enzyme colorimetric assay for galactose.

• Journal of Genetic Medicine
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• v.6 no.2
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• pp.170-174
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• 2009

Tetrahydrobiopterin ($BH_4$) deficiency is caused by mutations in genes encoding enzymes involved in the synthesis and regeneration of $BH_4$. The condition is usually accompanied by hyperphenylalaninemia (HPA) and deficiency of neurotransmitter precursors L-dopa and 5-hydroxytryptophan. $BH_4$ deficiency is much rarer than classical phenylketonuria. Dihydropteridine reductase (DHPR) deficiency, an autosomal recessive genetic disorder, is a cause of malignant hyperphenylalaninemia due to $BH_4$ deficiency. When left untreated, DHPR deficiency leads to neurologic deterioration at the age of 4 or 5 months, including psychomotor retardation, tonicity disorders, drowsiness, irritability, abnormal movements, hyperthermia, hypersalivation, and difficulty swallowing. Treatment of DHPR deficiency should be initiated as early as possible with $BH_4$ supplementation and replacement of the neurotransmitter precursors L-dopa and 5-hydroxytryptophan. We report the first case of DHPR deficiency in Korea, a child diagnosed at 9 years of age by genetic testing.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.15 no.2
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• pp.55-58
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• 2015

Tetrahydrobiopterin ($BH_4$) can normalize blood phenylalanine (Phe) levels in $BH_4$ deficiency, but typically not in phenylketonuria (PKU). In 1999, Kure et al. reported that some PKU patients showed decreased blood Phe levels after $BH_4$ loading, and thereafter, those PKU patients were identified by neonatal PKU screening. A natural cofactor for phenylalanine hydroxylase (PAH) is a 6R-isomer of $BH_4$, which is first synthesized in Japan as Sapropterin dihydrochloride (Biopten$^{(R)}$) in 1982. In Japan, Biopten$^{(R)}$ is first approved for the treatment of $BH_4$ deficiency in 1992, and then for $BH_4$-responsive PAH deficiency (BPKU) in 2008. The discovery of BPKU has vast clinical implications. After Biopten$^{(R)}$ (Kuvan$^{(R)}$) is available for the treatment of BPKU, the QOL of both patients and their families were improved very much, since the serum phenylalanine levels were controlled within 4 mg/dL by $BH_4$ mono-therapy with a normal diet or $BH_4$ combined use of mild phenylalanine-restricted diet. Biopten$^{(R)}$ therapy in patients with BPKU is highly efficacious (70%) at maintaining serum Phe levels within recommended control range and provides excellent safety at least average use period of 10 years (range, 1-17 years) with no unwarranted side effects in Japan. In addition it has been confirmed that sapropterin therapy initiated before 4 years of age was very effective to maintain plasma Phe levels within the favorable range and was safe in Japanese patients with BPKU.

• The Journal of Pediatrics of Korean Medicine
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• v.13 no.2
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• pp.41-77
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• 1999

The purpose of this research is that infant artificial feeding products is used in clonic with the study on characteristic, ingredients and indication of geneal and special modified milks. The result is as follows. 1. The main ingredients of four company products-Maeil , Namyang, Pasteur, Aebout is similar but the functional is different 2. General infant formula is divided into 100days, 5-6months, 12months, 24months and 36months out of consideration for growth and development of infant. 3. The indication and sorts of the special infant formula used at a hospital is as follows. PKU-1, PKU-2 formula is available for phenylketonuria. MPA formula is available for propionic acidemia and methylmalonic acidomia. UCD is available for urea cycle disorder Leucine-free formula is available for isovaleric acidemia. Maeil LP is available for hypocalcemia. MCT formula is available for indigestion and malabsorption of fat. BCAA-free formula is available for Maple syrup urine disease. Protein-free formula is available for limit of protein uptake or mixture of peculiar amino acid or higher uptake of mineral, vitamin, calory. Methionine-free formula is available for homocystinuria and hypermethioninemia. Premature infant is available for premature and low birth weight. 4. The special infant formula published in nation is as follows. Maeil soy A, Maeil MF1, Namyang hope doctor and Maeil HA is available for diarrhea. Maeil HA, Maeil HA-21 and Namyang hope allergy is available for hypoallergy. Maeil soy A is available for diarrhea of milk allergy. Maeil MF1 or Namyang hope doctor is available for acute bacterial or viral temporal diarrhea. Maeil HA is available for allergic chronic diarrhea. Maeil HA and Namyang hope allergy as eHP-formula is available for chronic diarrhea for lactose intolerance and milk allergy. Maeil-21 as pHP-formula for neonates with allergy family, allergic symptoms such as atopic dermatitis, asthma except digestive system.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.14 no.1
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• pp.1-9
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• 2014

Many inborn errors of metabolism can be completely cured with early detection and early treatment. This is why neonatal screening on inborn errors of metabolism is implemented worldwide. In 1991, the Ministry of Health & Social affairs adopted a nationwide service program for neonatal screening of phenylketonuria, galactosemia, maple syrup urine disease, homocystinuria, histidinemia and congenital hypothyroidism for newborns delivered from low class pregnant women registered in health centers. Government decreased the test items from six to two, PKU and congenital hypothyroidism to increase test numbers with same budget from 1995. 78 laboratories wanted to participate for neonatal screening test in 1999. Government decided to screen six items of PKU, congenital hypothyroidism, maple syrup urine disease, homocystinuria, galactosemia and congenital adrenal hyperplasia from 2006. In 2014, thirteen laboratories are participating. Inter laboratory quality control was started 6 times a year from 1994. In case a patient with an inherited metabolic disease is diagnosed by screening of government program, special milk is provided at government's expense. According to the government project, from 1997 to 2013, 7,080,569 newborns were screened. 144 PKU, 2.451 congenital hypothyroidism were detected. So incidence of PKU is 1/49,170 and congenital hypothyroidism is 1/2,888. The cost benefit of performing screening procedures coupled with treatment has been estimated to be as high as 1.77 times in PKU, 11.11 times in congenital hypothyroidism than cost without screening. By January 2007, many European countries had expanded of their newborn screening programs by inclusion of Tandem mass spectrometry. We are trying to increase the budget to test all newborns for Tandem mass spectrometry from 2016. We are considering four to five central laboratories which cover all newborns and are equipped with tandem mass spectrometer & enzyme immunoassay for TSH, 17OHP & enzyme colorimetric assay for galactose. And I hope to expand test including Wilson disease screening test and lysosomal storage diseases.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1375-1382
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• 2019

Phenylalanine hydroxylase from Chromobacterium violaceum (CvPAH) is a monomeric enzyme that converts phenylalanine to tyrosine. It shares high amino acid identity and similar structure with a subunit of human phenylalanine hydroxylase that is a tetramer, resulting in the latent application in medications. In this study, semirational design was applied to CvPAH to improve the catalytic ability based on molecular dynamics simulation analyses. Four N-terminal truncated variants and one single point variant were constructed and characterized. The D267P variant showed a 2.1-fold increased thermal stability compared to the wild type, but lower specific activity was noted compared with the wild type. The specific activity of all truncated variants was a greater than 25% increase compared to the wild type, and these variants showed similar or slightly decreased thermostability with the exception of the $N-{\Delta}9$ variant. Notably, the $N-{\Delta}9$ variant exhibited a 1.2-fold increased specific activity, a 1.3-fold increased thermostability and considerably increased catalytic activity under the neutral environment compared with the wild type. These properties of the $N-{\Delta}9$ variant could advance medical and pharmaceutical applications of CvPAH. Our findings indicate that the N-terminus might modulate substrate binding, and are directives for further modification and functional research of PAH and other enzymes.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.17 no.1
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• pp.11-17
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• 2017

Purpose: Phenylketonuria (PKU) results from a deficiency of phenylalanine hydroxylase (PAH). The mutation of the PAH gene results in decreased phenylalanine hydroxylase enzyme activity in hyperphenylalaninemia (HPA) patients. This study reports ten cases of patients with the benign HPA genotype c.158G>A (p.Arg53His, R53H) variant in the PAH gene and aims to evaluate the clinical significance of the R53H variant. Methods: Ten Korean patients with the HPA genotype the R53H variant were included in this study. A retrospective medical record review was conducted. We characterized the phenotypes of the patients with HPA with the R53H variant using the following system: classic PKU, moderate PKU, mild PKU, Mild HPA, and benign HPA. Results: Five patients had the R53H variant with the "Pathogenic" variants (R413P, R241C, $Y356^*$, c.442-1G>A, $Y325^*$), Two patients had the "Likely pathogenic" variants ($W187^*$, A259T), Two patients had the "Uncertain significance" variants (R53H, G344D), and One patient had the "Not provided" variant (c.1066-14C>G). Nine patients genotyped with the R53H variant were the patient with benign HPA and One patient genotyped with the R53H homozygote was within normal range of plasma phenylalanine. None of the ten patients required dietary restriction of phenylalanine or pharmacotherapy to maintain their plasma phenylalanine levels and showed no clinical symptoms of HPA. Conclusion: Ten patients with HPA genotype the R53H variant were the patient with benign HPA and showed no clinical symptoms of HPA. Thus, the R53H variant, which was previously classified as an "Uncertain significance" mutation in HPA patients, should be re-classified as "Benign."

• Journal of The Korean Society of Inherited Metabolic disease
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• v.16 no.2
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• pp.79-85
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• 2016

Purpose: This study aimed to analyze genetic mutations, clinical manifestations, and treatment of patients with benign HPA in Korea. Methods: This case series study involved ten HPA patients who were referred to our hospital because of high phenylalanine concentration. We investigated their demographic features, clinical manifestations, and mutations of the PAH gene through direct DNA sequencing. Results: Among ten patients with benign HPA, two pairs of patients were related (father-daughter, mother-daughter relationship) cases, and all of them showed no specific clinical manifestations or notable past history. Their plasma phenylalanine levels ranged between 1.2 and 4.2 mg/dL. In the tetrahydrobiopterin (BH4) loading test, all patients were nonresponsive to BH4. In the confirmation test of PAH mutation analysis, we identified eleven different alleles out of twelve. The most common allele was R53H (c.158G> A). In addition, two novel PAH gene mutations, V423A (c.1268T>C) and V51A (c.152T>C), were identified. Although the patients did not receive any pharmacologic treatment or continuous phenylalanine restriction dietary therapy, their neurocognitive development was normal. Moreover, on serial outpatient follow-up tests, all patients maintained phenylalanine levels below 6 mg/dL. Conclusion: This study is the first in Korea to analyze benign HPA patients. All patients with benign HPA could maintain phenylalanine levels below 6 mg/dL with normal neurocognitive development, without continuous therapy. Therefore, performing mutation analysis and distinguishing benign HPA from phenylketonuria (PKU) are important to help improve life quality in patients with benign HPA by avoiding unnecessary lifelong therapy.