L-Dopa-responsive Parkinson's syndrome in association with phenylketonuria: In vivo dopamine transporter and D2 receptor findings.

Reports of parkinsonism in phenylketonuria are exceedingly rare. We report on a patient who had received a delayed diagnosis of phenylketonuria as an infant and subsequently developed levodopa-responsive parkinsonism at the age of 33. Single-photon emission computed tomography (SPECT) using (123)I-FP-CIT ([(123))I]-2 beta-carbomethoxy-3beta-(-4-iodophenyl)-N-(3-fluoropropyl)-nortropane) used to measure dopamine transporter levels on two occasions, 7 and 9 years after the onset of neurological symptoms, were normal. Iodine-123-iodo-lisuride SPECT (IBZM) imaging, however, showed reduced caudate over putamen binding. This combination of imaging findings indicates a possible upregulation of postsynaptic D2 receptors in the context of intact presynaptic dopamine nerve terminal density.     

Decreased trabecular bone mineral density in patients with phenylketonuria measured by peripheral quantitative computed tomography

The bone mineral density (BMD) of 14 children, adolescents, and adults with phenylketonuria (PKU) on dietary treatment (age 5-28 y; 6F, 8M) was investigated using peripheral quantitative computed tomography (pQCT) of the distal radius. BMD of total (TBMD) and spongy bone (SBMD) were compared to those of healthy gender-, age-, weight- and height-matched controls. We found a significant decrease of SBMD in patients with PKU while TBMD was only slightly decreased, reaching no statistical significance. These results indicate minor changes of BMD in patients with PKU under treatment, which are more accentuated in the trabecular bone compartment. One additional patient who was untreated until the pQCT investigation at the age of 10 y also showed markedly decreased SBMD and TBMD.     

Molecular basis of phenylketonuria and related hyperphenylalaninemias: mutations and polymorphisms in the human phenylalanine hydroxylase gene.

Mutations in the human phenylalanine hydroxylase gene producing phenylketonuria or hyperphenylalaninemia have now been identified in many patients from various ethnic groups. These mutations all exhibit a high degree of association with specific restriction fragment-length polymorphism haplotypes at the PAH locus. About 50 of these mutations are single-base substitutions, including six nonsense mutations and eight splicing mutations, with the remainder being missense mutations. One splicing mutation results in a 3 amino acid in-frame insertion. Two or 3 large deletions, 2 single codon deletions, and 2 single base deletions have been found. Twelve of the missense mutations apparently result from the methylation and subsequent deamination of highly mutagenic CpG dinucleotides. Recurrent mutation has been observed at several of these sites, producing associations with different haplotypes in different populations. About half of all missense mutations have been examined by in vitro expression analysis, and a significant correlation has been observed between residual PAH activity and disease phenotype. Since continuing advances in molecular methodologies have dramatically accelerated the rate in which new mutations are being identified and characterized, this register of mutations will be updated periodically.     

A Three-Year Longitudinal Study Comparing Bone Mass,Density, and Geometry Measured by DXA,pQCT, and Bone Turnover Markers in Children with PKU Taking L-Amino Acid or Glycomacropeptide Protein Substitutes

In patients with phenylketonuria (PKU), treated by diet therapy only, evidence suggests that areal bone mineral density (BMDa) is within the normal clinical reference range but is below the population norm. Aims: To study longitudinal bone density, mass, and geometry over 36 months in children with PKU taking either amino acid (L-AA) or casein glycomacropeptide substitutes (CGMP-AA) as their main protein source. Methodology: A total of 48 subjects completed the study, 19 subjects in the L-AA group (median age 11.1, range 5–16 years) and 29 subjects in the CGMP-AA group (median age 8.3, range 5–16 years). The CGMP-AA was further divided into two groups, CGMP100 (median age 9.2, range 5–16 years) (n = 13), children taking CGMP-AA only and CGMP50 (median age 7.3, range 5–15 years) (n = 16), children taking a combination of CGMP-AA and L-AA. Dual X-ray absorptiometry (DXA) was measured at enrolment and 36 months, peripheral quantitative computer tomography (pQCT) at 36 months only, and serum blood and urine bone turnover markers (BTM) and blood bone biochemistry at enrolment, 6, 12, and 36 months. Results: No statistically significant differences were found between the three groups for DXA outcome parameters, i.e., BMDa (L2–L4 BMDa g/cm²), bone mineral apparent density (L2–L4 BMAD g/cm³) and total body less head BMDa (TBLH g/cm²). All blood biochemistry markers were within the reference ranges, and BTM showed active bone turnover with a trend for BTM to decrease with increasing age. Conclusions: Bone density was clinically normal, although the median z scores were below the population mean. BTM showed active bone turnover and blood biochemistry was within the reference ranges. There appeared to be no advantage to bone density, mass, or geometry from taking a macropeptide-based protein substitute as compared with L-AAs.     

235361例新生儿疾病筛查情况分析

目的调查黄冈市2016年1月1日—2019年6月30日新生儿遗传代谢性疾病的筛查结果。方法采用实时数据分析调查的方法,对黄冈市2016年1月1日—2019年6月30日出生并在黄冈市妇幼保健院进行遗传代谢病5项[先天性甲状腺功能减低症(CH)、苯丙酮尿症(PKU)、葡萄糖-6-磷酸脱氢酶(G6PD)缺乏症、先天性肾上腺皮质增生症(CAH)和地中海贫血]检测的235361例活产新生儿的结果及确诊数据进行分析和统计。结果2016年1月1日—2019年6月30日期间共筛查235361例新生儿,确诊CH患儿61例,发病率约为1:3858;确诊PKU患儿14例,发病率约为1:16812;确诊G6PD缺乏症(蚕豆病)患儿179例,发病率约为1:1315;确诊CAH患儿9例,发病率约为1:26151;确诊地中海贫血患儿446例,发病率约为1:528。结论黄冈市CH、PKU、G6PD缺乏症、CAH及地中海贫血发病率均低于全国平均发病率。加强健康教育和普及,通过分析质量控制指标加强质量管理,规范筛查流程,减少漏筛,提高召回确诊病例,不断提高服务质量。     

Intellectual and Developmental Status in Children With Hyperphenylalaninemia and PKU Who Were Screened in a National Program

Background:

Hyperphenylalaninemia (HPA) and Phenylkeonuria (PKU) are metabolic errors caused by deficiency of phenylalanine hydroxylase enzyme, which results in increased level of phenylalanine. This increase is toxic to the growing brain.

Objectives:

The purpose of this study was to compare the intellectual and developmental status in HPA and PKU children with normal population in national screening program.

Patients and Methods:

In a historical cohort study, 41 PKU patients who had the inclusion criteria and 41 healthy children were evaluated. Wechsler preschool and primary scale of intelligence-3rd edition (WPPI-3) was used in order to assess the intellectual status of children 4 years and older and Ages and stages questionnaire (ASQ) was used to assess the developmental status of children 5 years and younger.

Results:

In intellectual test comparison, the two groups showed significant difference in Wechsler’s performance intelligence score and some performance subscales (P-value < 0.01). In comparison of developmental status, no significant difference was observed between the two groups (P-value > 0.05).

Conclusions:

Even with early diagnosis and treatment of PKU patients, these children show some deficiencies intellectually compared to normal children. This study emphasizes on necessity for screening intellectual and developmental status of PKU patients so that effective medical or educational measures can taken in case of deficiencies.     

Mutational spectrum of the phenylalanine hydroxylase gene in patients with phenylketonuria in the central region of China

Phenylketonuria (PKU, OMIM 261600) caused by phenylalanine hydroxylase (PAH) deficiency is an autosomal recessive disease that is characterized by abnormalities of phenylalanine metabolism. In this study, a total of 77 patients, originating from the central region of China and who were diagnosed with PAH deficiency at the third affiliated hospital of Zhengzhou University, were enrolled in this study. The 13 exons and 12 flanking introns of the PAH gene were analyzed by Sanger sequencing and next generation sequencing. The sequencing data were aligned to the hg19, PAHvdb and HGMD databases to characterize the genotypes of PKU patients, and genotype–phenotype correlations and BH4 responsiveness predictions were performed using BIOPKUdb. In total, 149 alleles were characterized among the 154 PKU alleles. These mutations were located in exons 2–13, and intron 12 of the PAH gene, with a relative frequency of ≥5%, for EX6-96A>G, p.R241C, p.R243Q, p.V399V and p.R53H. Additionally, a novel variant, p.D84G, was identified. The genotype correlated with clinical symptoms in 33.3–100% of the cases, depending on the disease severity, and BH4 responsiveness predictions show that only five patients with MHP-PKU and one patient with Mild-PKU were predicted to be BH4 responsive. In conclusion, we have characterized the mutational spectrum of PAH in the central region of China and have identified a novel mutation. The hotspot mutation information might be useful for screening, diagnosis and treatment of PKU.     

近14年四川省新生儿 PKU 及 CH 筛查情况分析

目的：分析四川省近14年间新生儿苯丙酮尿症（ PKU）和先天性甲状腺功能减低症（ CH）的筛查情况,为卫生行政部门提供决策依据。方法医务人员开展新生儿疾病筛查健康教育,经家长知情同意后对出生72小时后的新生儿进行血样标本采集、保存和递送;新筛中心及时验收血样标本,对合格标本进行PKU和CH筛查,对可疑或阳性结果进行复查,复查阳性者通知确诊。结果14年来四川省新生儿苯丙酮尿症和先天性甲状腺功能减低症筛查率和覆盖面逐年明显提高,2013年筛查率达到91．74％,市（州）筛查覆盖率达到100％,县（区）筛查覆盖率达到94．48％,采血单位覆盖率达到74．30％,年度筛查率、市（州）、县（区）、采血单位筛查覆盖率均有极显著性差异（χ2值分别为4530453．36、157．76、970．97、12314．65,均P＜0．01）。2000至2013年四川省新生儿PKU和CH筛查数为4348607,成都市新筛中心、自贡市新筛中心、南充市新筛中心、四川省新筛中心的年度筛查率均有极显著性差异（χ2值分别为879606．29、601375．16、379461．09、3030668．08,均P＜0．01）;确诊PKU138例,PKU发生率为1：31511,CH1711例,CH发生率为1：2542,各年度CH发病率有显著性差异（χ2＝37．59,P＜0．01）,各年度PKU发病率无显著性差异（χ2＝11．01,P＞0．05）。四川省新生儿苯丙酮尿症和先天性甲状腺功能减低症筛查仍有提升空间,筛查工作还有待进一步深入。结论14年来四川省新生儿苯丙酮尿症和先天性甲状腺功能减低症筛查工作取得明显成效,显示出明显的社会效益,需进一步加大相关工作力度,提高新生儿遗传代谢病筛查率和筛查质量。     

比较两种方法在新生儿苯丙酮尿症筛查中的应用

目的比较串联质谱（tandemmassspectrometry,TMS）技术与茚三酮荧光法在苯丙酮尿症（phenylketonuria,PKU）筛查中的准确性。方法采用茚三酮荧光法对166247例PKU标本进行初筛,初查阳性标本均采用茚三酮荧光法和串联质谱技术复查,复查阳性者召回采血后统一再用上述两种方法进行检测,通过卡方检验统计比较两种方法的复查阳性率,探讨这两种方法在苯丙酮尿症筛查中的应用。根据血中Phe浓度进行鉴别诊断。结果（1）166247例新生儿初查阳性1152例,初查阳性率为6．93‰;（2）茚三酮荧光法和TMs技术的复查阳性率分别为14．58％、3．91％,两种方法比较具有统计学意义（P〈0．05）;（3）复查阳性者召回采血后统一再用上述两种方法进行检测,均确诊HPA3例,发病率为1：55415,其中经典型PKU2例,高苯丙氨酸血症1例。结论TMS技术能更快速、更准确地监测血苯丙氨酸水平,更适合用于PKU筛查,可有效地开展筛查的阳性召回工作及缓解家庭的精神压力。