Racial and ethnic diversity of classic and clinical variant galactosemia in the United States.

Classic and clinical variant galactosemia (CG/CVG) are allelic, autosomal recessive disorders that result from deficiency of galactose-1-P uridylyltransferase (GALT). CG/CVG has been reported globally among patients of diverse ancestries, but most large studies of outcomes have included, almost exclusively, patients categorized as White or Caucasian. As a first step to explore whether the cohorts studied are representative of the CG/CVG population at large, we sought to define the racial and ethnic makeup of CG/CVG newborns in a diverse population with essentially universal newborn screening (NBS) for galactosemia: the United States (US). First, we estimated the predicted racial and ethnic distribution of CG/CVG by combining the reported demographics of US newborns from 2016 to 2018 with predicted homozygosity or compound heterozygosity of pathogenic, or likely pathogenic, GALT alleles from the relevant ancestral groups. Incorporating some simplifying assumptions, we predicted that of US newborns diagnosed with CG/CVG, 65% should be White (non-Hispanic), 23% should be Black (non-Hispanic), 10% should be Hispanic, and 2% should be Asian (non-Hispanic). Next, we calculated the observed racial and ethnic distribution of US newborns diagnosed with CG/CVG using available de-identified data from state NBS programs from 2016 to 2018. Of the 235 newborns in this cohort, 41 were categorized as other or unknown. Of the remaining 194, 66% were White (non-Hispanic or ethnicity unknown), 16% were Black (non-Hispanic or ethnicity unknown),15% were Hispanic, and 2% were Asian (non-Hispanic or ethnicity unknown). This observed distribution was statistically indistinguishable from the predicted distribution. To the limits of our study, these data confirm the racial and ethnic diversity of newborns with CG/CVG in the US, demonstrate an approach for estimating CG/CVG racial and ethnic diversity in other populations, and raise the troubling possibility that current understanding of long-term outcomes in CG/CVG may be skewed by ascertainment bias of the cohorts studied.

Neonatal classic galactosemia-diagnosis, clinical profile and molecular characteristics in unscreened Turkish population.

BACKGROUND: Classic galactosemia (CG) is a rare hereditary disease that can cause serious morbidity and death if it is not diagnosed and treated in early periods of life. Clinical findings usually occur in the neonatal period after the neonate is fed with milk that contains galactose. Most patients are presented with jaundice, hepatomegaly, hypoglycemia and cataracts. OBJECTIVE: We aimed to document the clinical, molecular characteristics, regional estimated incidence and time of diagnosis in newborn with CG. MATERIALS AND METHOD: The data of 63 newborn with CG who were diagnosed and followed up between January 2011 and January 2018 were analyzed retrospectively. RESULTS: During the study period, 63 (33 boys and 30 girls) newborns were diagnosed with CG. The median gestational age was 39 weeks (33-42). Major presenting symptoms were jaundice 90.5% and cataract 41.2%. The mean age at first symptom was 12 ± 7.4 days while the mean age at diagnosis was 18.9 ± 10.6 days. Nearly half of the patients (55.5%) were diagnosed later than the postnatal 15th day. Genetic analysis was performed on 56 patients and homozygous Q188R mutation was found in 92.8%. There were signs of sepsis in 33.3% of the cases. Six patients died due to sepsis. There was consanguinity in 84.1% of the parents and regional estimated incidence was calculated as 1 in 6103 live births. CONCLUSION: Q188R mutation was found in 92.8% of our cases. The regional estimated incidence was found as 1 in 6103 live births. Our study strongly supports that galactosemia should be included in the national newborn screening program.

Galactokinase deficiency: lessons from the GalNet registry.

PURPOSE: Galactokinase (GALK1) deficiency is a rare hereditary galactose metabolism disorder. Beyond cataract, the phenotypic spectrum is questionable. Data from affected patients included in the Galactosemias Network registry were collected to better characterize the phenotype. METHODS: Observational study collecting medical data of 53 not previously reported GALK1 deficient patients from 17 centers in 11 countries from December 2014 to April 2020. RESULTS: Neonatal or childhood cataract was reported in 15 and 4 patients respectively. The occurrence of neonatal hypoglycemia and infection were comparable with the general population, whereas bleeding diathesis (8.1% versus 2.17-5.9%) and encephalopathy (3.9% versus 0.3%) were reported more often. Elevated transaminases were seen in 25.5%. Cognitive delay was reported in 5 patients. Urinary galactitol was elevated in all patients at diagnosis; five showed unexpected Gal-1-P increase. Most patients showed enzyme activities ≤1%. Eleven different genotypes were described, including six unpublished variants. The majority was homozygous for NM_000154.1:c.82C>A (p.Pro28Thr). Thirty-five patients were diagnosed following newborn screening, which was clearly beneficial. CONCLUSION: The phenotype of GALK1 deficiency may include neonatal elevation of transaminases, bleeding diathesis, and encephalopathy in addition to cataract. Potential complications beyond the neonatal period are not systematically surveyed and a better delineation is needed.

NGS-based expanded carrier screening for genetic disorders in North Indian population reveals unexpected results - a pilot study.

BACKGROUND: To determine the carrier frequency and pathogenic variants of common genetic disorders in the north Indian population by using next generation sequencing (NGS). METHODS: After pre-test counselling, 200 unrelated individuals (including 88 couples) were screened for pathogenic variants in 88 genes by NGS technology. The variants were classified as per American College of Medical Genetics criteria. Pathogenic and likely pathogenic variants were subjected to thorough literature-based curation in addition to the regular filters. Variants of unknown significance were not reported. Individuals were counselled explaining the implications of the results, and cascade screening was advised when necessary. RESULTS: Of the 200 participants, 52 (26%) were found to be carrier of one or more disorders. Twelve individuals were identified to be carriers for congenital deafness, giving a carrier frequency of one in 17 for one of the four genes tested (SLC26A4, GJB2, TMPRSS3 and TMC1 in decreasing order). Nine individuals were observed to be carriers for cystic fibrosis, with a frequency of one in 22. Three individuals were detected to be carriers for Pompe disease (frequency one in 67). None of the 88 couples screened were found to be carriers for the same disorder. The pathogenic variants observed in many disorders (such as deafness, cystic fibrosis, Pompe disease, Canavan disease, primary hyperoxaluria, junctional epidermolysis bullosa, galactosemia, medium chain acyl CoA deficiency etc.) were different from those commonly observed in the West. CONCLUSION: A higher carrier frequency for genetic deafness, cystic fibrosis and Pompe disease was unexpected, and contrary to the generally held view about their prevalence in Asian Indians. In spite of the small sample size, this study would suggest that population-based carrier screening panels for India would differ from those in the West, and need to be selected with due care. Testing should comprise the study of all the coding exons with its boundaries in the genes through NGS, as all the variants are not well characterized. Only study of entire coding regions in the genes will detect carriers with adequate efficiency, in order to reduce the burden of genetic disorders in India and other resource poor countries.

How a baby with classic galactosemia was nearly missed: When the test succeeds but system fails.

Newborn screening (NBS) is a well-established state-run public health program which has targeted the early identification of treatable diseases like classic galactosemia (CG) for over a decade. We describe the case of a symptomatic newborn with CG and an abnormal screen report, including positive DNA-based test, who still managed to fall through the cracks in a sub-optimally functioning NBS program, despite decades of screening experience. While much attention is paid to testing technology, this case illustrates basic minimum requirements a newborn screening program must fulfill to reliably identify and treat all affected individuals including minimum reporting requirements, case surveillance and a dedicated short-term follow-up program. In newborn screening, success is systematic.

Newborn Screening for Five Conditions in a Tertiary Care Government Hospital in Bengaluru, South India-Three Years Experience.

PURPOSE: Newborn screening is the need of the hour in a developing country like India as there is paucity of data from studies conducted in government hospitals with large sample size. The purpose of the study is to estimate incidence rate and recall rates for five conditions screened in the neonatal period namely congenital hypothyroidism, congenital adrenal hyperplasia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, galactosemia and phenyl ketonuria (PKU). METHODS: The study was conducted at VaniVilas Hospital attached to Bangalore Medical College and Research Institute. A retrospective analysis of the results of newborn screening programme during a 3-year period between January 2016 and December 2018 was done. There were 47 623 livebirths during this period out of which 41 027 babies were screened (coverage-86% of total livebirths). Heelprick samples after 48 h of life and prior to discharge were analysed by quantitative assessment. Neonates having positive screening results were recalled by telephonic call for repeat screening and confirmatory tests. RESULTS: G6PD deficiency was the most common disorder with an incidence of 1:414, followed by congenital hypothyroidism and Congenital Adrenal Hyperplasia with an incidence of 1:2735 and 1:4102, respectively. Galactosemia and PKU were found to be rare in our population. The overall average recall rate was 0.6% which meant that 24 normal newborns were recalled for testing for one confirmed case. The recall rate was relatively higher for galactosemia and G6PD deficiency which was at 0.25% each compared to the other conditions where it was below 0.05%. CONCLUSION: The results of the study emphasize the need for universal newborn screening especially in all government hospitals with large birth cohorts.

Classic galactosaemia in the Greek Cypriot population: An epidemiological and molecular study.

Classic galactosaemia is an inherited metabolic disorder of galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT) resulting from mutations in the GALT gene. The objectives of the present study were the determination of the carrier frequency of classic galactosaemia in the Greek Cypriot population and the molecular characterization of the disease alleles. We performed an epidemiological study involving 528 Greek Cypriots originating from all parts of Cyprus. Carriers were identified by measuring GALT activity in red blood cells and were subsequently subjected to mutation analysis. A total of five mutations were identified in patients and carriers of classic galactosaemia: a large deletion of 8.5 kb previously reported by us (55% of alleles), the known mutations p.Lys285Asn (30%), p.Pro185Ser (5%), and c.820+13A>G (5%), and a novel mutation c.378-12G>A (5%). Interestingly, the most common mutation in European populations, p.Gln188Arg, was not identified in this Cypriot cohort. The carrier frequency for classic galactosaemia among Greek Cypriots was estimated to be 1:88, predicting a homozygote incidence of 1:31,000 births. The Duarte 1 and Duarte 2 variants were found to be present at a frequency of 5.5% and 2.5%, respectively.

The prevalence of GALM mutations that cause galactosemia: A database of functionally evaluated variants.

Galactosemia is a metabolic disorder that affects the appropriate metabolism of ß-D-galactose. Deficiencies in three of the enzymes of the Leloir pathway, namely, GALT, GALK1, or GALE, are characterized as type I, II, and III galactosemia, respectively. Recently, we reported a novel type of galactosemia (type IV galactosemia) due to biallelic GALM mutations. Genetic diagnosis is indispensable for diagnosing GALM deficiency because no biochemical diagnosis method has been established. Given that apparently pathogenic variants in GALM are found in public variant databases, we presumed the presence of pathogenic variants that have not been reported. In this study, we explore 67 GALM variants that are prevalent in the ExAC database, including 57 missense variants, 7 stop-gain variants, 2 frameshift variants, and 1 splice-site variant. We performed an in vitro expression assay and an enzyme activity assay. Among the 66 variants except for 1 splice-site variant, 29 produced no or faint protein expression and were judged as pathogenic variants. Furthermore, the remaining 37 variants were evaluated by enzyme activity assay. Two showed mildly reduced enzyme activity and were classified as benign. Based on our study, the estimated incidence of GALM deficiency is 1:228,411 in all populations, 1:10,388 in the African population, and 1:80,747 in the Japanese population. Our GALM mutation database is useful for the genetic diagnosis of GALM deficiency.

Estimates of the Prevalence of Speech and Motor Speech Disorders in Youth With 22q11.2 Deletion Syndrome.

Purpose Speech sound disorders and velopharyngeal dysfunction are frequent features of 22q11.2 deletion syndrome (22q). We report the first estimate of the prevalence of motor speech disorders (MSDs) in youth with 22q. Method Seventeen children and adolescents with 22q completed an assessment protocol that included a conversational speech sample. Data reduction included phonetic transcription, perceptual speech ratings, prosody-voice coding, and acoustic analyses. Data analyses included 3 motor speech measures and a cross-classification analytic. Prevalence estimates of speech and MSDs in youth with 22q were compared with estimates in speakers with other complex neurodevelopmental disorders: Down syndrome, fragile X syndrome, and galactosemia. Results Results indicated that 58.8% of the participants with 22q met criteria for speech delay, and 82.4% of the participants met criteria for MSDs, including 29.4% with speech motor delay, 29.4% with childhood dysarthria, 11.8% with childhood apraxia of speech, and 11.8% with concurrent childhood dysarthria and childhood apraxia of speech. MSDs were not significantly associated with velopharyngeal dysfunction. Conclusions In summary, 82.4% of the participants with 22q met criteria for 1 of 4 MSDs, predominantly speech motor delay and childhood dysarthria. Cross-validation of the present findings would support viewing MSDs as a core phenotypic feature of 22q.

Recommendations for newborn screening for galactokinase deficiency: A systematic review and evaluation of Dutch newborn screening data.

INTRODUCTION: Galactokinase (GALK) deficiency causes cataract leading to severe developmental consequences unless treated early. Because of the easy prevention and rapid reversibility of cataract with treatment, the Dutch Health Council advised to include GALK deficiency in the Dutch newborn screening program. The aim of this study is to establish the optimal screening method and cut-off value (COV) for GALK deficiency screening by performing a systematic review of the literature of screening strategies and total galactose (TGAL) values and by evaluating TGAL values in the first week of life in a cohort of screened newborns in the Netherlands. METHODS: Systematic literature search strategies in OVID MEDLINE and OVID EMBASE were developed and study selection, data collection and analyses were performed by two independent investigators. A range of TGAL values measured by the Quantase Neonatal Total Galactose screening assay in a cohort of Dutch newborns in 2007 was evaluated. RESULTS: Eight publications were included in the systematic review. All four studies describing screening strategies used TGAL as the primary screening marker combined with galactose-1-phosphate uridyltransferase (GALT) measurement that is used for classical galactosemia screening. TGAL COVs of 2200 µmol/L, 1665 µmol/L and 1110 µmol/L blood resulted in positive predictive values (PPV) of 100%, 82% and 10% respectively. TGAL values measured in the newborn period were reported for 39 GALK deficiency patients with individual values ranging from 3963 to 8159 µmol/L blood and 2 group values with mean 8892 µmol/L blood (SD ±â€¯5243) and 4856 µmol/L blood (SD ±â€¯461). Dutch newborn screening data of 72,786 newborns from 2007 provided a median TGAL value of 110 µmol/L blood with a range of 30-2431 µmol/L blood. CONCLUSION: Based on TGAL values measured in GALK deficiency patients reported in the literature and TGAL measurements in the Dutch cohort by newborn screening we suggest to perform the GALK screening with TGAL as a primary marker with a COV of 2500 µmol/L blood, combined with GALT enzyme activity measurement as used in the classical galactosemia screening, to ensure detection of GALK deficiency patients and minimize false positive referrals.

Molecular basis and clinical presentation of classic galactosemia in a Croatian population.

BACKGROUND: Classic galactosemia is an autosomal recessive disorder of galactose metabolism caused by severely decreased activity of galactose-1-phosphate uridylyltransferase (GALT) due to pathogenic mutations in the GALT gene. To date more than 330 mutations have been described, with p.Q188R and p.K285N being the most common in Caucasian populations. Although acute manifestations can be fully avoided by a galactose-restricted diet, chronic complications, such as neurological ones, cannot be prevented in a significant number of patients despite compliance with the dietary treatment. METHODS: A cohort of 16 galactosemic Croatian patients, including one pair of siblings, was studied. Molecular characterization was performed by direct sequence analysis of the GALT gene. RESULTS: Sixteen patients were analyzed and only four different mutations were detected. As expected, p.Q188R and p.K285N were common, accounting for 40% and 37% of unrelated alleles, respectively. The third mutation accounting for 20% of mutant alleles was p.R123X causing a premature stop codon, is thus considered to be severe, which is in accordance with the phenotype presented by the homozygous patient described here. The fourth mutation p.E271D was found in a single allele. More than half of our patients manifested some chronic neurological complications. CONCLUSIONS: This is the first report on mutational and phenotypic spectra of classic galactosemia in Croatia that expands the knowledge on the mutational map of the GALT gene across Europe and reveals the genetic homogeneity of the Croatian population.

Association of presenile cataract with galactose-1-phosphate uridyl transferase gene mutations.

BACKGROUND: Presenile cataract is commonly idiopathic in origin. However, patients with presenile cataract could have an underlying genetic abnormality of galactose metabolism. We studied the association, if any, between idiopathic presenile cataract and galactose-1 -phosphate uridyl transferase (GALT) gene mutation. METHODS: We selected 50 patients with idiopathic presenile cataract, <45 years of age, and 50 age- and sex-matched controls for the study. Mutations in the GALT gene were determined by polymerase chain reaction restriction fragment length polymorphism. The classical galactosaemia was characterized by Q188R and K285N mutations, whereas Duarte galactosaemia by N314D mutations (Duarte-2: N314D with IVS5-24G >A and Duarte-1: N314D without IVS5- 24G>A). RESULTS: The most common mutation observed was the N314D (Duarte) mutation. The frequencies of classical and N31 4D alleles in patients with presenile cataract (16%) and controls (26%) were not statistically different (p=0.32, OR 0.54, 95% CI 0.20-1.45). Similarly, there was no statistically significant difference in the frequency distribution of Duarte-1 (p=0.77, OR 0.77, 95% CI 0.23-0.24) and Duarte-2 (p=0.44, OR 0.38, 95% CI 0.07-2.03) galactosaemia mutations in patients and controls. CONCLUSION: Duarte galactosaemia, a milder form of the disease, is more common than classical galactosaemia in the Indian population. Duarte galactosaemia is unlikely to be a causative factor in presenile cataract.

Fertility in adult women with classic galactosemia and primary ovarian insufficiency.

OBJECTIVE: To study pregnancy chance in adult women with classic galactosemia and primary ovarian insufficiency. Despite dietary treatment, >90% of women with classic galactosemia develop primary ovarian insufficiency, resulting in impaired fertility. For many years, chance of spontaneous conception has not been considered, leading to counseling for infertility. But an increasing number of reports on pregnancies in this group questions whether current counseling approaches are correct. DESIGN: Multicenter retrospective observational study. SETTING: Metabolic centers. PATIENT(S): Adult women (aged >18 y) with confirmed classic galactosemia and primary ovarian insufficiency were included. INTERVENTION(S): Participants and medical records were consulted to obtain study data in a standardized manner with the use of a questionnaire. MAIN OUTCOME MEASURE(S): Conception opportunities, time to pregnancy, pregnancy outcome, hormone replacement therapy use, fertility counseling, and the participants' vision of fertility were evaluated. Potential predictive factors for increased pregnancy chance were explored. RESULT(S): Eighty-five women with classic galactosemia and primary ovarian insufficiency participated. Twenty-one women actively attempted to conceive or did not take adequate contraceptive precautions. Of these 21 women, nine became pregnant spontaneously (42.9%). This was higher than reported in primary ovarian insufficiency due to other causes (5%-10%). After a period of 12 months, a cumulative proportion of 27.8% of couples had conceived, which increased to 48.4% after 24 months and 61.3% after 27 months. Predictive factors could not be identified. A considerable miscarriage rate of 30% was observed (6 of 20 pregnancies). Although a substantial proportion of women expressed a child-wish (n = 28/53; 52.8%), the vast majority of participants (n = 43/57; 75.4%) considered conceiving to be highly unlikely, owing to negative counseling in the past. CONCLUSION(S): The pregnancy rate in women with classic galactosemia and primary ovarian insufficiency was higher than for women with primary ovarian insufficiency of any cause. This shifting paradigm carries significant implications for fertility counseling and potential application of fertility preservation techniques.

Classical Galactosemia Among Indian Children: Presentation and Outcome from a Pediatric Gastroenterology Center.

OBJECTIVE: To analyze the presentation and predictors of outcome of children with galactosemia. METHODS: Analysis of clinical, laboratory, microbiological profile and outcome of patients fulfilling the diagnostic criteria: i) clinical setting; ii) reduced erythrocyte Gal-1-PUT enzyme activity; and iii) unequivocal response to lactose-free diet. RESULTS: 24 patients; median age of symptom onset and diagnosis: 10 (3-75) d and 55 (15-455) days, respectively. 71% had uncorrectable coagulopathy; 71% systemic infections; and 54% had ascites. CONCLUSION: Despite delayed referral, high Pediatric end-stage liver disease scores and systemic infections, long-term outcome in galactosemia is rewarding. A subset of children have developmental delay.

Newborn screening for galactosemia: a 30-year single center experience.

BACKGROUND: Galactosemia due to complete or near-complete galactose-1-phosphate uridyltransferase (GALT) deficiency was the first disorder added to the pioneering newborn screening panel besides phenylketonuria. In the last 50 years, many criticisms have been focused on the opportunity of its inclusion. Consequently, long-term single center experiences with this issue are generally lacking. METHODS: We reviewed the outcome of newborn screening for hypergalactosemia performed at our department since 1982 and the correspondent long-term clinical outcome. RESULTS: Among 1 123 909 newborns screened for hypergalactosemia, 33 showed abnormal results confirmed at second tier test. Thirteen patients were affected with classic galactosemia, 8 partial GALT deficiency, 3 severe galactokinase deficiency, 7 transient galactosemia, one congenital porto-systemic shunt, and one glucose transporter 2 deficiency. Acute neonatal liver failure in the late first week of life (5.8±1.1 days) unavoidably complicated the clinical course of classic galactosemia, unless in three second-born siblings treated on the basis of presumptive diagnosis immediately after newborn screening sample collection on day 3. Despite early treatment and long-term steadily normal peripheral blood galactose, 77% of patients with severe GALT deficiency present mild to severe intellectual disabilities. All patients with partial GALT deficiency showed normal intellectual development on a regular diet, as well as patients with galactokinase deficiency under treatment. CONCLUSIONS: Availability of screening results within the fifth day after birth would allow the prevention of acute decompensation in classic galactosemia. A systematic diagnostic work-up in all positive newborns is essential to unravel the etiology of hypergalactosemia.

Newborn screening for congenital hypothyroidism, galactosemia and biotinidase deficiency in Uttar Pradesh, India.

OBJECTIVE: To assess feasibility and recall rates for newborn screening for congenital hypothyroidism, galactosemia and biotinidase deficiency in a predominantly rural and inner city population in and around the City of Lucknow in Uttar Pradesh, India. DESIGN: Prospective observational study. SETTING: Two tertiary-care and 5 district hospitals in and around Lucknow. PARTICIPANTS: All babies born in above hospitals during the study period. METHODS: Heel prick samples were collected after 24 hours of life. Dried blood spot TSH, total galactose and biotinidase were assayed by immunofluorometry. Age related cut-offs were applied for recall for TSH. For galactosemia and biotinidase deficiency, manufacturer-suggested recall cut-offs used initially were modified after analysis of initial data. MAIN OUTCOME MEASURE: Recall rate for hypothyroidism, galactosemia and biotinidase deficiency. RESULTS: Screening was carried out for 13426 newborns, 73% of all deliveries. Eighty-five percent of those recalled for confirmatory sampling responded. Using fixed TSH cut off of 20 mIU/L yielded high recall rate of 1.39%, which decreased to 0.84% with use of age-related cut-offs. Mean TSH was higher in males, and in low birth weight and vaginally delivered babies. Eleven babies had congenital hypothyroidism. Recall rates with modified cut-offs for galactosemia and biotinidase deficiency were 0.32% and 0.16%, respectively. CONCLUSIONS: An outreach program for newborn screening can be successfully carried out in similar socio-cultural settings in India. For hypothyroidism, the high recall rate due to early discharge was addressed by age-related cut-offs.

[What disorders suspect following an increase of phenylalanine on newborn screening?]. / Quelles pathologies suspecter suite à une augmentation de la phénylalanine lors du dépistage néonatal ?

Screening for PKU, in France, is made on the 3rd day of life by measuring the concentration of phenylalanine in dried blood spot samples. In this study, the goal was to examine the final diagnosis of patients who showed a hyperphenylalaninemia during newborn screening laboratory. Over a period of 11 years from 1 February 2002 to 31 January 2013, all newborns with a phenylalanine concentration increase (>180 µmol/L) have been identified and the cause of this increase was noted. Of the 165,113 newborns screened, hyperphenylalaninemia was identified in 90 patients during the newborn screening laboratory. During this period 35% of cases were due to classical phenylketonuria or hyperphenylalaninemia. In 4.4% of cases, increase concentrations were due to other diseases (biopterine deficiency, galactosemia, MSUD). However, 48.9% of high concentrations have not been confirmed by a second sample and 11% were children who died rapidely during their first days of life. The positive predictive value (PPV) of the test with a threshold of positivity >180 µmol/L was 40%. Our study showed that the positivity threshold of 180 µmol/L proposed by the Association française pour le dépistage et la prévention des handicaps de l'enfant (AFDPHE) provides a comprehensive detection of all phenylketonuria cases as well as mild hyperphenylalaninemia permanent and transient cases. Eventhough the use of a higher threshold would have the advantage of increasing the PPV of the test, none the less we would have missed out on some cases to follow.