Newborn screening for severe primary immunodeficiencies (PID), characterized by T and/or B cell lymphopenia, was carried out in a pilot program in the Stockholm County, Sweden, over a 2-year period, ...encompassing 58,834 children. T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) were measured simultaneously using a quantitative PCR-based method on DNA extracted from dried blood spots (DBS), with beta-actin serving as a quality control for DNA quantity. Diagnostic cutoff levels enabling identification of newborns with milder and reversible T and/or B cell lymphopenia were also evaluated. Sixty-four children were recalled for follow-up due to low TREC and/or KREC levels, and three patients with immunodeficiency (Artemis-SCID, ATM, and an as yet unclassified T cell lymphopenia/hypogammaglobulinemia) were identified. Of the positive samples, 24 were associated with prematurity. Thirteen children born to mothers treated with immunosuppressive agents during pregnancy (azathioprine (
n
= 9), mercaptopurine (
n
= 1), azathioprine and tacrolimus (
n
= 3)) showed low KREC levels at birth, which spontaneously normalized. Twenty-nine newborns had no apparent cause identified for their abnormal results, but normalized with time. Children with trisomy 21 (
n
= 43) showed a lower median number of both TREC (104 vs. 174 copies/μL blood) and KREC (45 vs. 100 copies/3.2 mm blood spot), but only one, born prematurely, fell below the cutoff level. Two children diagnosed with DiGeorge syndrome were found to have low TREC levels, but these were still above the cutoff level. This is the first large-scale screening study with a simultaneous detection of both TREC and KREC, allowing identification of newborns with both T and B cell defects.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary
The brain aspartate‐glutamate carrier (AGC1) is specifically expressed in neurons, where it transports aspartate from the mitochondria to the cytosol, and plays a role in transfer of ...nicotinamide adenine dinucleotide (NADH)‐reducing equivalents into the mitochondria as a part of the malate‐aspartate shuttle. Deficient function of AGC1 underlies an inborn error of metabolism that presents with severe hypotonia, arrested psychomotor development, and seizures from a few months of age. In AGC1 deficiency, there is secondary hypomyelination due to lack of N‐acetylaspartate (NAA), which is normally generated by acetylation of aspartate in the neuron and required for fatty acid synthesis by the adjacent oligodendrocyte. Based on experiences from AGC2 deficiency, we predicted that reduced glycolysis should compensate for the metabolic defect and allow resumed myelination in AGC1 deficiency. Carbohydrate restriction was therefore initiated in a patient with AGC1 deficiency at 6 years of age by introducing a ketogenic diet. The response was dramatic, clinically as well as radiologically. Psychomotor development showed clear improvement, and magnetic resonance imaging (MRI) indicated resumed myelination. This is the first successful treatment of secondary hypomyelination reported. Because AGC1 is driven by the proton gradient generated by the neuronal mitochondrial respiratory chain, the results have potential relevance for secondary hypomyelination in general.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We report the findings from 4437 individuals (3219 patients and 1218 relatives) who have been analyzed by whole genome sequencing (WGS) at the Genomic Medicine Center Karolinska-Rare Diseases ...(GMCK-RD) since mid-2015. GMCK-RD represents a long-term collaborative initiative between Karolinska University Hospital and Science for Life Laboratory to establish advanced, genomics-based diagnostics in the Stockholm healthcare setting.
Our analysis covers detection and interpretation of SNVs, INDELs, uniparental disomy, CNVs, balanced structural variants, and short tandem repeat expansions. Visualization of results for clinical interpretation is carried out in Scout-a custom-developed decision support system. Results from both singleton (84%) and trio/family (16%) analyses are reported. Variant interpretation is done by 15 expert teams at the hospital involving staff from three clinics. For patients with complex phenotypes, data is shared between the teams.
Overall, 40% of the patients received a molecular diagnosis ranging from 19 to 54% for specific disease groups. There was heterogeneity regarding causative genes (n = 754) with some of the most common ones being COL2A1 (n = 12; skeletal dysplasia), SCN1A (n = 8; epilepsy), and TNFRSF13B (n = 4; inborn errors of immunity). Some causative variants were recurrent, including previously known founder mutations, some novel mutations, and recurrent de novo mutations. Overall, GMCK-RD has resulted in a large number of patients receiving specific molecular diagnoses. Furthermore, negative cases have been included in research studies that have resulted in the discovery of 17 published, novel disease-causing genes. To facilitate the discovery of new disease genes, GMCK-RD has joined international data sharing initiatives, including ClinVar, UDNI, Beacon, and MatchMaker Exchange.
Clinical WGS at GMCK-RD has provided molecular diagnoses to over 1200 individuals with a broad range of rare diseases. Consolidation and spread of this clinical-academic partnership will enable large-scale national collaboration.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Severe combined immunodeficiency (SCID) and X-linked agammaglobulinemia (XLA) are inborn errors of immune function that require prompt diagnosis and treatment to prevent life-threatening infections. ...The lack of functional T or B lymphocytes in these diseases serves as a diagnostic criterion and can be applied to neonatal screening. A robust triplex PCR method for quantitation of T-cell receptor excision circles (TRECs) and κ-deleting recombination excision circles (KRECs), using a single Guthrie card punch, was developed and validated in a cohort of 2560 anonymized newborn screening cards and in 49 original stored Guthrie cards from patients diagnosed with SCID, XLA, ataxia-telangiectasia, Nijmegen-breakage-syndrome, common variable immunodeficiency, immunoglobulin A deficiency, or X-linked hyper-IgMsyndrome. Simultaneous measurement of TREC and KREC copy numbers in Guthrie card samples readily identified patients with SCID, XLA, ataxia-telangiectasia and Nijmegen-breakage-syndrome and thus facilitates effective newborn screening for severe immunodeficiency syndromes characterized by the absence of T or B cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Four inborn errors of metabolism (IEMs) are known to cause hypermethioninemia by directly interfering with the methionine cycle. Hypermethioninemia is occasionally discovered incidentally, but it is ...often disregarded as an unspecific finding, particularly if liver disease is involved. In many individuals the hypermethioninemia resolves without further deterioration, but it can also represent an early sign of a severe, progressive neurodevelopmental disorder. Further investigation of unclear hypermethioninemia is therefore important. We studied two siblings affected by severe developmental delay and liver dysfunction. Biochemical analysis revealed increased plasma levels of methionine, S-adenosylmethionine (AdoMet), and S-adenosylhomocysteine (AdoHcy) but normal or mildly elevated homocysteine (Hcy) levels, indicating a block in the methionine cycle. We excluded S-adenosylhomocysteine hydrolase (SAHH) deficiency, which causes a similar biochemical phenotype, by using genetic and biochemical techniques and hypothesized that there was a functional block in the SAHH enzyme as a result of a recessive mutation in a different gene. Using exome sequencing, we identified a homozygous c.902C>A (p.Ala301Glu) missense mutation in the adenosine kinase gene (
ADK), the function of which fits perfectly with this hypothesis. Increased urinary adenosine excretion confirmed ADK deficiency in the siblings. Four additional individuals from two unrelated families with a similar presentation were identified and shown to have a homozygous c.653A>C (p.Asp218Ala) and c.38G>A (p.Gly13Glu) mutation, respectively, in the same gene. All three missense mutations were deleterious, as shown by activity measurements on recombinant enzymes. ADK deficiency is a previously undescribed, severe IEM shedding light on a functional link between the methionine cycle and adenosine metabolism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aim
There are more than 50 inherited lysosomal storage diseases (LSDs), and this study examined the incidence of clinically diagnosed LSDs in Sweden.
Methods
The number of patients diagnosed during ...1980–2009 was compiled from the registries of the two Swedish diagnostic laboratories that cover the whole country.
Results
We identified 433 patients during the 30‐year period, with a total incidence of one in every 6100 births and identified fairly constant annual diagnoses during the last 20 years. Krabbe disease was the most common (one in 39 000) followed by Gaucher disease (one in 47 000), metachromatic leukodystrophy and Salla disease. Gaucher disease was more frequent in Sweden than other European countries, due to a founder effect of the mutation (p.L444P) in northern Sweden. Metachromatic leukodystrophy was one of the most common LSDs, in common with other countries. Salla disease, which is very rare elsewhere, was the fourth most common, stemming from a founder mutation in the Salla region of northern Finland brought to Sweden by immigration.
Conclusion
The collective incidence of LSDs in Sweden was essentially equal to other European countries, but with a somewhat different disease pattern. Our findings have implications for diagnostic algorithms and treatment strategies.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The aim was to determine disease‐causing variants in the GALT gene which codes for the enzyme galactose‐1‐phosphate uridylyltransferase. Loss of activity of this enzyme causes classical ...galactosemia—a life threatening, treatable disorder, included in the Swedish newborn screening program since 1967. A total of 66 patients with the disease are known in Sweden and 56 index patients were investigated. An additional two patients with Duarte galactosemia were included. The disease‐causing variants were identified in all patients. As reported from other countries only a few variants frequently recur in severe disease. The two variants p.(Gln188Arg) (c.563A>G) and p.(Met142Lys) (c.425T>A) are present in several index patients whereas the remaining are found in one to three patients each. The most common variant, p.(Gln188Arg), has an allele frequency of 51% in the cohort. A total of 16 novel variants were found among the 33 different variants in the cohort. Two of these are synonymous variants affecting splicing, demonstrating the importance of the evaluation of synonymous variants at the cDNA level. Concise sentence: Galactosemia is a rare disease in Sweden and the disease‐causing variants are heterogenous including two synonymous variants.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Congenital adrenal hyperplasia due to 21-hydroxylase deficiency results in cortisol and aldosterone deficiency and is, in its most severe form, lethal. We aimed to assess the effect of historical ...medical improvements in the care of patients with this disorder over time and to assess the effects of neonatal screening in Sweden.
For this retrospective, population-based cohort study, we collected data for all known patients with congenital adrenal hyperplasia in Sweden between 1910 and 2011 corrected. Data sources included the registry at the Swedish national screening laboratory, patients identified via the Swedish neonatal screening programme, late-diagnosed patients reported to the laboratory, and patients who underwent genetic diagnostics or became known to us through clinical contacts. All known patients were included in a population-based cohort study of the distribution of clinical severity, genotype, sex, and the effect of nationwide neonatal screening.
We identified 606 patients with the disorder, born between 1915 and 2011. The CYP21A2 genotype (conferring deficiency of 21-hydroxylase) was known in 490 patients (81%). The female-to-male ratio was 1·25 in the whole cohort, but close to 1 in patients detected by the screening. We noted a sharp increase in the number of patients diagnosed in the 1960s and 1970s, and after the introduction of neonatal screening in 1986 the proportion of patients with the salt-wasting form of congenital adrenal hyperplasia increased in both sexes, from 114 (47%) of 242 individuals between 1950 and 1985 to 165 (57%) of 292 individuals between 1986 and 2011 (p=0·038). On average, five to ten children were missed every year before 1970. The non-classic form of the disorder was diagnosed more often in women than in men, which accounts for the female preponderance in our cohort.
Our findings suggest that, contrary to current belief, boys and girls with salt-wasting congenital adrenal hyperplasia were equally missed clinically. Neonatal screening improved detection of the salt-wasting form in girls as well as boys, saving lives in both sexes. The non-classic form was diagnosed more often in women than it was in men, leading to the female preponderance in this cohort.
The Swedish Research Council, the Centre of Gender Medicine at Karolinska Institutet, the Stockholm County Council, the Sällskapet Barnavård Foundation, the Stiftelsen Samariten Foundation, the Stiftelsen Frimurare Barnhuset Foundation, and the Novo Nordisk Foundation.
To the Editor: Severe combined immunodeficiency (SCID) is the most severe form of primary immunodeficiency with profound defects in both the cellular and humoral immune defence.1-3 The affected ...newborns are highly susceptible to life-threatening opportunistic bacterial, viral, and/or fungal infections.1-5 Early detection of SCID in the preinfectious period followed by hematopoietic stem cell transplantation (HSCT) has been shown to dramatically improve survival.1 This has led to the implementation of national newborn screening (NBS) programs in selected countries and pilot projects ongoing in many additional countries.6 Two studies from the United States and France of real-life costs for HSCT in SCID have been published and both showed that early HSCT resulted in lower treatment-related costs.7,8 The aim of this study was to use patient-unique, individual, real-life cost and care data to calculate costs for children with SCID undergoing HSCT in Sweden, and to identify types and percentage breakdown of the costs. ...once a child has passed the first post-HSCT year and survived, the costs for health care were limited. The study also demonstrated important health benefits for the children and the families from early HSCT, such as reduction by more than half of in-hospital days 3 6 of 6 15 118 Year +4 0 0 0 0 3 of 3 4 of 6 9 101 Year +5 0 0 0 0 2 of 2 4 of 6 4 73 Total 663 1461 302 787 Table E3Outpatient clinic visits for each child for the entire cost follow-up period for children before and...
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
IMPORTANCE Recent reports have questioned the rationale for neonatal screening for congenital adrenal hyperplasia (CAH) owing to low sensitivity in salt-wasting forms and a high rate of recall (ie, a ...positive finding resulting in a visit to a pediatrician and a second test) in preterm infants. OBJECTIVE To determine the efficiency of the neonatal screening program for CAH in Sweden over time. DESIGN, SETTING, AND PARTICIPANTS Longitudinal prospective population-based study in Sweden. We assessed neonatal screening for CAH from January 1, 1986, through December 31, 2011, when 2 737 932 infants (99.8%) underwent testing. The CYP21A2 genotype was investigated in 219 cases with true-positive findings (94.8%). We investigated the screening outcomes for 231 patients who had true-positive findings, 43 with late diagnosis, and 1497 infants with false-positive findings. MAIN OUTCOMES AND MEASURES Sensitivity of the screening for salt-wasting CAH. The most important secondary outcome measures were the positive predictive values and recall rates for full-term and preterm infants and sensitivity for milder forms of CAH. RESULTS A total of 143 patients with salt-wasting CAH were identified; none were missed. The sensitivity was lower for milder forms of the disorder (P = .04), including 79.7% for simple virilizing forms and 32.4% for nonclassic forms. The positive predictive value was higher in full-term (25.1%) than preterm (1.4%) infants and correlated with gestational age (r = 0.98; P < .001). The recall rate in full-term infants (0.03%) was lower than that in preterm infants (0.57%) (P < .001). An analysis of previously reported results from other screening programs revealed that the sensitivity of the screening was negatively correlated with the duration of follow-up (P = .03). CONCLUSIONS AND RELEVANCE Screening for CAH was highly effective in detecting the salt-wasting form and thereby reducing mortality. Additional late-onset cases of CAH were detected in childhood and adolescence, reducing the sensitivity for milder forms. The positive predictive value was high despite a low recall rate in full-term infants. Further improvements are necessary to increase the effectiveness of screening among preterm infants.
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