Epidemiology of rare diseases detected by newborn screening in the Czech Republic.

OBJECTIVES: Presymptomatic detection of patients with rare diseases (RD), defined by a population frequency less than 1 : 2,000, is the task of newborn screening (NBS). In the Czech Republic (CZ), currently eighteen RD are screened: phenylketonuria/hyperphenylalaninemia (PKU/HPA), congenital hypothyroidism (CH), congenital adrenal hyperplasia (CAH), cystic fibrosis (CF), medium chain acyl-CoA dehydrogenase deficiency (MCADD), long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), very long chain acyl-CoA dehydrogenase deficiency (VLCADD), carnitine palmitoyl transferase I and II deficiency (CPTID, CPTIID), carnitine-acylcarnitine translocase deficiency (CACTD), maple syrup urine disease (MSUD), glutaric aciduria type I (GA I), isovaleryl-CoA dehydrogenase deficiency (IVA), argininemia (ARG), citrullinemia (CIT), biotinidase deficiency (BTD), cystathionine beta-synthase-deficient homocystinuria (CBSD HCU), and methylenetetrahydrofolate reductase deficiency homocystinuria (MTHFRD HCU). The aim was to analyze the prevalence of RD screened by NBS in CZ. METHODS: We examined the NBS programme in CZ from 1 January 2010 to 31 December 2017, which covered 888,891 neonates. Dried blood spots were primarily analyzed using fluorescence immuno-assay, tandem mass spectrometry and fluorimetry. RESULTS: The overall prevalence of RD among the neonate cohort was 1 : 1,043. Individually, 1 : 2,877 for CH, 1 : 5,521 for PKU/HPA, 1 : 6,536 for CF (1 : 5,887 including false negative patients), 1 : 12,520 for CAH, 1 : 22,222 for MCADD, 1 : 80,808 for LCHADD, 1 : 177,778 for GA I, 1 : 177,778 for IVA, 1 : 222,223 for VLCADD, 1 : 296,297 for MSUD, 1 : 8,638 for BTD, and 1 : 181,396 for CBSD HCU. CONCLUSIONS: The observed prevalence of RD, based on NBS, corresponds to that expected, more precisely it was higher for BTD and lower for MSUD, IVA, CBSD HCU, MCADD and VLCADD. Early detection of rare diseases by means of NBS is an effective secondary prevention tool.

Neonatal screening in the Czech Republic: increased prevalence of selected diseases in low birthweight neonates.

Neonates with low birthweight (LBW) represent a vulnerable population. This retrospective study analyzed the birth frequency of diseases detected by neonatal screening (NBS) in normal and LBW neonates in the Czech Republic. Between years 2002 and 2016, the number of screened disorders in the Czech Republic gradually increased from two to 13. Prevalence of screened diseases was calculated for cohorts ranging from 777,100 to 1,277,283 neonates stratified by birthweight. Odds ratio of the association of LBW with each disease was calculated and statistical significance was evaluated using the chi-square test or Fisher's exact test, as appropriate. Three diseases were associated with higher risk of prevalence in LBW neonates, namely congenital hypothyroidism (OR 2.50, CI 1.92; 3.25), cystic fibrosis (OR 2.44, CI 1.51; 3.94), and long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) (OR 7.74, CI 2.18; 27.42).Conclusion: Although the underlying mechanisms are not well understood, results can be hypothesized that LBW (respectively prematurity) may lead to the secondary and often transitory hypothyroidism while cystic fibrosis and LCHADD may manifest already prenatally and result into preterm birth and LBW. What is Known: • The percentage of low birthweight (LBW) neonates in the Czech Republic has been increasing. • Previously published studies reported positive association between LBW and congenital hypothyroidism and cystic fibrosis. What is New: • The association between LCHADD and LBW has not yet been described. • LBW can be the first manifestation of cystic fibrosis and LCHADD.

Effect of Hydrolyzed Infant Formula vs Conventional Formula on Risk of Type 1 Diabetes: The TRIGR Randomized Clinical Trial.

Importance: Early exposure to complex dietary proteins may increase the risk of type 1 diabetes in children with genetic disease susceptibility. There are no intact proteins in extensively hydrolyzed formulas. Objective: To test the hypothesis that weaning to an extensively hydrolyzed formula decreases the cumulative incidence of type 1 diabetes in young children. Design, Setting, and Participants: An international double-blind randomized clinical trial of 2159 infants with human leukocyte antigen-conferred disease susceptibility and a first-degree relative with type 1 diabetes recruited from May 2002 to January 2007 in 78 study centers in 15 countries; 1081 were randomized to be weaned to the extensively hydrolyzed casein formula and 1078 to a conventional formula. The follow-up of the participants ended on February 28, 2017. Interventions: The participants received either a casein hydrolysate or a conventional adapted cow's milk formula supplemented with 20% of the casein hydrolysate. The minimum duration of study formula exposure was 60 days by 6 to 8 months of age. Main Outcomes and Measures: Primary outcome was type 1 diabetes diagnosed according to World Health Organization criteria. Secondary outcomes included age at diabetes diagnosis and safety (adverse events). Results: Among 2159 newborn infants (1021 female [47.3%]) who were randomized, 1744 (80.8%) completed the trial. The participants were observed for a median of 11.5 years (quartile [Q] 1-Q3, 10.2-12.8). The absolute risk of type 1 diabetes was 8.4% among those randomized to the casein hydrolysate (n = 91) vs 7.6% among those randomized to the conventional formula (n = 82) (difference, 0.8% [95% CI, -1.6% to 3.2%]). The hazard ratio for type 1 diabetes adjusted for human leukocyte antigen risk group, duration of breastfeeding, duration of study formula consumption, sex, and region while treating study center as a random effect was 1.1 (95% CI, 0.8 to 1.5; P = .46). The median age at diagnosis of type 1 diabetes was similar in the 2 groups (6.0 years [Q1-Q3, 3.1-8.9] vs 5.8 years [Q1-Q3, 2.6-9.1]; difference, 0.2 years [95% CI, -0.9 to 1.2]). Upper respiratory infections were the most common adverse event reported (frequency, 0.48 events/year in the hydrolysate group and 0.50 events/year in the control group). Conclusions and Relevance: Among infants at risk for type 1 diabetes, weaning to a hydrolyzed formula compared with a conventional formula did not reduce the cumulative incidence of type 1 diabetes after median follow-up for 11.5 years. These findings do not support a need to revise the dietary recommendations for infants at risk for type 1 diabetes. Trial Registration: clinicaltrials.gov Identifier: NCT00179777.

Pendred syndrome among patients with congenital hypothyroidism detected by neonatal screening: identification of two novel PDS/SLC26A4 mutations.

Pendred syndrome is an autosomal recessive disorder characterised by sensorineural hearing loss and thyroid dyshormonogenesis. It is caused by mutations in the PDS/SLC26A4 gene (OMIM 605646) encoding for pendrin. Hypothyroidism in Pendred syndrome can be--although rarely--present from birth and therefore diagnosed by neonatal screening. The aim of our study was to identify patients with Pendred syndrome among a historical cohort of patients with congenital hypothyroidism (CH) identified by neonatal screening, and to find their mutations in the PDS/SLC26A4 gene. We investigated 197 Czech Caucasian children with CH detected by the neonatal screening between the years 1985 and 2005. The clinical diagnosis of Pendred syndrome was based on the laboratory and sonographic signs of thyroid dyshormonogenesis in association with sensorineural hearing loss. In subjects clinically diagnosed with Pendred syndrome, we sequenced all exons and exon-intron boundaries of the PDS/SLC26A4 gene. Hearing loss was present in 10/197 children with screening-detected CH. Of these, three fulfilled the diagnostic criteria of Pendred syndrome. Two patients were compound heterozygotes for PDS/SLC26A4 mutations: patient 1 carried c.2089+1G>A / c.3G>C and patient 2 carried p.Tyr530His / p.Val422Asp. Two of the four identified mutations were novel (c.3G>C in patient 1 and p.Val422Asp in patient 2). The third patient was free of mutations in the PDS/SLC26A4 gene, representing a phenocopy. In conclusion, our results indicate the rarity of Pendred syndrome as a cause of CH. The identification of two novel mutations expands the spectrum of mutations in the PDS/SLC26A4 gene and emphasizes their marked allelic heterogeneity.

Thyroidectomy in a patient with multinodular dyshormonogenetic goitre--a case of Pendred syndrome confirmed by mutations in the PDS/SLC26A4 gene.

We report a young woman with genetically confirmed Pendred syndrome and discuss the current therapeutic strategies of dyshormonogenetic goitre. A small diffuse thyroid enlargement developed during infancy and although substitution therapy with L-thyroxine was adequate, it progressed and underwent multinodular transformation. Cervical ultrasound at the age of 22 years demonstrated three solid nodules and fine-needle aspiration biopsy showed a finding typical of follicular adenoma. It is known that dyshormonogenetic goitres have a tendency to grow despite appropriate treatment with L-thyroxine. Management of a patient with Pendred syndrome requires careful follow-up and regular imaging of the thyroid. Although the therapeutic approach to dyshormonogenetic goitres is still controversial, in our patient we chose total thyroidectomy as the most advantageous method to prevent the development of malignancies that may arise more frequently from dyshormonogenetic goitres than from goitres of other aetiologies.

Screening for mutations in transcription factors in a Czech cohort of 170 patients with congenital and early-onset hypothyroidism: identification of a novel PAX8 mutation in dominantly inherited early-onset non-autoimmune hypothyroidism.

OBJECTIVE: Mutations in NKX2.1, NKX2.5, FOXE1 and PAX8 genes, encoding for transcription factors involved in the development of the thyroid gland, have been identified in a minority of patients with syndromic and non-syndromic congenital hypothyroidism (CH). DESIGN: In a phenotype-selected cohort of 170 Czech paediatric and adolescent patients with non-goitre CH, including thyroid dysgenesis, or non-goitre early-onset hypothyroidism, PAX8, NKX2.1, NKX2.5, FOXE1 and HHEX genes were analysed for mutations. METHODS: NKX2.1, NKX2.5, FOXE1 and HHEX genes were directly sequenced in patients with syndromic CH. PAX8 mutational screening was performed in all 170 patients by single-stranded conformation polymorphism, followed by direct sequencing of samples with abnormal findings. The R52P PAX8 mutation was functionally characterized by DNA binding studies. RESULTS: We identified a novel PAX8 mutation R52P, dominantly inherited in a three-generation pedigree and leading to non-congenital, early-onset, non-goitre, non-autoimmune hypothyroidism with gradual postnatal regression of the thyroid size and function. The R52P PAX8 mutation results in the substitution of a highly conserved residue of the DNA-binding domain with a loss-of-function effect. CONCLUSIONS: The very low frequency of genetic defects in a population-based cohort of children affected by non-goitre congenital and early-onset hypothyroidism, even in a phenotype-focussed screening study, suggests the pathogenetic role of either non-classic genetic mechanisms or the involvement of genes unknown so far. Identification of a novel PAX8 mutation in a particular variant of non-congenital early-onset hypothyroidism indicates a key function of PAX8 in the postnatal growth and functional maintenance of the thyroid gland.

Allelic heterogeneity in the COH1 gene explains clinical variability in Cohen syndrome.

Cohen syndrome is a rare autosomal recessive disorder with a variable clinical picture mainly characterized by developmental delay, mental retardation, microcephaly, typical facial dysmorphism, progressive pigmentary retinopathy, severe myopia, and intermittent neutropenia. A Cohen syndrome locus was mapped to chromosome 8q22 in Finnish patients, and, recently, mutations in the gene COH1 were reported in patients with Cohen syndrome from Finland and other parts of northern and western Europe. Here, we describe clinical and molecular findings in 20 patients with Cohen syndrome from 12 families, originating from Brazil, Germany, Lebanon, Oman, Poland, and Turkey. All patients were homozygous or compound heterozygous for mutations in COH1. We identified a total of 17 novel mutations, mostly resulting in premature termination codons. The clinical presentation was highly variable. Developmental delay of varying degree, early-onset myopia, joint laxity, and facial dysmorphism were the only features present in all patients; however, retinopathy at school age, microcephaly, and neutropenia are not requisite symptoms of Cohen syndrome. The identification of novel mutations in COH1 in an ethnically diverse group of patients demonstrates extensive allelic heterogeneity and explains the intriguing clinical variability in Cohen syndrome.