Prevalence of classical phenylketonuria in mentally retarded individuals in Iran

Phenylketonuria in Portugal: Genotype-phenotype correlations using molecular, biochemical, and haplotypic analyses

Background

The impairment of the hepatic enzyme phenylalanine hydroxylase (PAH) causes elevation of phenylalanine levels in blood and other body fluids resulting in the most common inborn error of amino acid metabolism (phenylketonuria). Persistently high levels of phenylalanine lead to irreversible damage to the nervous system. Therefore, early diagnosis of the affected individuals is important, as it can prevent clinical manifestations of the disease.

Methods

In this report, the biochemical and genetic findings performed in 223 patients diagnosed through the Portuguese Neonatal Screening Program (PNSP) are presented.

Results

Overall, the results show that a high overlap exists between different types of variants and phenylalanine levels. Molecular analyses reveal a wide mutational spectrum in our population with a total of 56 previously reported variants, most of them found in compound heterozygosity (74% of the patients). Intragenic polymorphic markers were used to assess the haplotypic structure of mutated chromosomes for the most frequent variants found in homozygosity in our population (p.Ile65Thr, p.Arg158Gln, p.Leu249Phe, p.Arg261Gln, p.Val388Met, and c.1066‐11G>A).

Conclusion

Our data reveal high heterogeneity at the biochemical and molecular levels and are expected to provide a better understanding of the molecular basis of this disease and to provide clues to elucidate genotype–phenotype correlations.

Genetic variants of the phenylalanine hydroxylase gene in patients with phenylketonuria in the northeast of Iran

Background Phenylketonuria (PKU) is a common metabolic disorder with great burden if left untreated or undiagnosed. Genetic variations in the phenylalanine hydroxylase (PAH) gene may be widely varied across different regions of a country. By knowing the most common mutations, diagnostic work-ups will be offered sooner and with lower costs for patients. The present study defines the most common genetic variations in the PAH gene in Khorasan province of Iran. Methods The present cross-sectional study took place in Khorasan province of Iran within a 6-year period starting from 2012 to 2018. Every patient who had been referred as suspicious PKU cases or referred for prenatal diagnosis was included in the present study. Results A total number of 122 individuals with a mean age of 26.22 years were enrolled in the present study. The most frequent genetic variations in the PAH gene were c.1066-11G > A and c.143 T > C. Exon 7 carried the most genetic variations compared to any single exon. Also, three patients had compound heterozygous status for c.727 C > T/c.1066-11 G > A in exon 7 and 11 of the PAH gene. Conclusions Mutations in the PAH gene are widely varied among different populations, and our results confirmed this fact. Determination of the most prevalent mutations and polymorphisms in each region will reduce the time and cost of diagnosing such preventable diseases and will therefore reduce the disease burden.

A comprehensive study of phenylalanine hydroxylase gene mutations in the Iranian phenylketonuria patients

Phenylketonuria (PKU) is a metabolic disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene. After thalassemia, PKU is considered as the most common autosomal recessive diseases in the Iranian population. Therefore, an efficient diagnostic strategy is required to identify disease-causing mutations in this population. Following our first report in 2003, here we presented a comprehensive study on the mutation spectrum of the PAH gene in the Iranian population. This study was performed on 280 unrelated chromosomes from 140 Iranian patients with classic PKU. All 13 exons as well as exon-intron boundaries of the PAH gene were analyzed by direct DNA sequencing. Thirty four different mutations were identified by a mutation detection rate of 100%. IVS10-11G > A, p.P281L, R261Q, p.F39del and IVS11+1G > C were the most prevalent mutations with frequencies of 26.07%, 19.3%, 12.86%, 6.07 and 3.93%, respectively. All other mutations represented a relative frequency less than 3.5%. The data from this study provided a comprehensive spectrum of the PAH gene mutations which can facilitate carrier detection and prenatal diagnosis of PKU disease in the Iranian population.

A novel compound-primed multiplex ARMS-PCR (CPMAP) for simultaneous detection of common PAH gene mutations

In this study, we introduce a novel compound-primed multiplex ARMS PCR (CPMAP) for simultaneous detection of common PAH gene mutations. This approach was used successfully for simultaneous identification of six most common PAH gene mutations in 137 phenylketonuria patients in the Iranian population. A total of six normal and six mutant allele-specific primers and 4 common primers containing a tag sequence of 12 base pair at the 5'-end were designed and used in two separate optimized multiplex ARMS reactions followed by hot-start PCR. The products were separated and visualized on 3% agarose gel. The CPMAP genotyping data were completely in accordance with the direct sequencing results. The CPMAP suggests a reliable, economical and rapid method for simultaneous detection of PAH point mutations using conventional PCR, which could be applied for diagnosis of other gene mutations.

The Prevalence of Phenylketonuria in Arab Countries, Turkey, and Iran: A Systematic Review

Background/Objectives

This paper seeks to identify the prevalence of Phenylketonuria (PKU) in Arab countries, Turkey, and Iran. The study reviewed the existence of comprehensive national newborn screening programs and reported consanguinity rates.

Methods

A computer based literature search was conducted using relevant keywords to retrieve studies conducted on PKU. A total of 34 articles were included. Prevalence was categorized based on the type of screening method used for PKU diagnoses.

Results

The prevalence of classical PKU diagnosed through a comprehensive national newborn screening program ranged from 0.005% to 0.0167%. The highest prevalence was reported in Turkey at 0.0167%, whereas the lowest prevalence was reported in the UAE, 0.005%.

Conclusion

The findings of this review emphasize the need for the establishment of more efficient reporting systems in these countries that would help measure Disability-Adjusted Life Year (DALY) in order to estimate the overall societal burden of PKU.

Phenylketonuria screening and management in southeastern Europe - survey results from 11 countries

BACKGROUND

We aimed to assess the current state of PKU screening and management in the region of southeastern Europe.

METHODS

A survey was performed involving all identified professionals responsible for the PKU management in the 11 countries from South-Eastern region of Europe (Albania, Bulgaria, Bosnia and Herzegovina, Croatia, Kosovo, Macedonia, Moldova, Montenegro, Romania, Serbia, Slovenia). The questionnaire was designed to assess the characteristics regarding PKU management in three main areas: nation-wide characteristics, PKU screening, and characteristics of the PKU management in the responding centre. It consisted of 56 questions. The distribution and collection of the questionnaires (via e-mail) was taking place from December 2013 to March 2014.

RESULTS

Responses from participants from 11 countries were included; the countries cumulative population is approx. 52.5 mio. PKU screening was not yet introduced in 4 of 11 countries. Reported PKU incidences ranged from 1/7325 to 1/39338 (and were not known for 5 countries). National PKU guidelines existed in 5 of 11 countries and 7 of 11 countries had PKU registry (registries included 40 to 194 patients). The number of PKU centers in each country varied from 1 to 6. Routine genetic diagnostics was reported in 4 of 11 countries. Most commonly used laboratory method to assess phenylalanine levels was fluorometric. Tetrahydrobiopterine was used in only 2 of 11 countries. Most frequently, pediatricians were caring for the patients. Dietitian was a member of PKU team in only 4 of 11 countries, while regular psychological assessments were performed in 6 of 11 countries. Patient's PKU society existed in 7 of 11 countries.

CONCLUSIONS

The region of southeastern Europe was facing certain important challenges of PKU screening and management. Neonatal PKU screening should be introduced throughout the region. Furthermore, PKU management was falling behind internationally established standards-of-care in many aspects.