Neonatal screening for congenital hypothyroidism: Time to lower the TSH threshold in France.

Neonatal screening for congenital hypothyroidism (CH) is based on the measurement of thyroid-stimulating hormone (TSH) in whole dried blood samples on filter paper in all newborns. The objective of screening for CH is to prevent mental retardation, which is irreversible in the event of a late diagnosis, by setting up prompt treatment (before day 15) with levothyroxine. The threshold value of TSH on filter paper on day 3 is 17 mIU/L in France in the GSP method (GSP, Genetic Screening Processor, Perkin Elmer): It is one of the highest thresholds used in the world. In many countries, the TSH threshold is between 6 and 12 mIU/L. Studies have found that a threshold of > 17 mIU/L may miss as much as 30% of cases of CH, with 30-80% of these being permanent CH. Recent studies suggest that mild CH (currently missed by the French TSH threshold) is associated with cognitive consequences if left untreated. An inverse relationship between TSH at screening (below the current threshold) and cognitive development at preschool or school age has been shown. These studies advocate for the evaluation of a lowering of the threshold of TSH on filter paper in France: (a) to determine the number of CH diagnoses with the new threshold and whether these "new cases" would be transitory or permanent; and (b) to analyze the cost-effectiveness of the strategy.

Large triglyceride-rich lipoproteins from fasting patients with type 2 diabetes activate platelets.

AIMS: Type 2 diabetes (T2D) patients present with risk factors for atherothrombosis such as fasting hypertriglyceridaemia and platelet hyperactivity. Our study objective was to determine the effect of large triglyceride-rich lipoproteins (TGRL) from fasting T2D patients on platelet aggregation and, if any, to identify the signaling pathway involved. METHODS: Large TGRL were isolated from the plasma of 25 T2D patients by ultracentrifugation (density < 1.000 g/mL). Platelets were isolated from healthy blood donors (HBD) and suspended in buffer, then preincubated in the presence or absence of TGRL and stimulated with either collagen or thrombin. Platelet aggregation and the arachidonic acid (AA) signaling pathway were studied. RESULTS: Fasting T2D large TGRL were mostly of hepatic origin (apoB100/apoB48 ratio: 42 ± 7) and rich in triglycerides (TG/total apoB ratio: 4.2 ± 0.5), and able to potentiate agonist-stimulated platelet aggregation (collagen: +68%, P < 0.05; thrombin: +771%, P < 0.05). It should also be mentioned that TGRL from the plasma of HBD (n = 7) had no effect on platelet aggregation. In addition, T2D large TGRL increased thromboxane B2 (TxB2) concentration in platelets stimulated with either collagen (+34%, P < 0.05) or thrombin (+37%, P < 0.05) compared with platelets stimulated with either of these agonists without TGRL. Phosphorylation of p38 MAPK and cytosolic phospholipase A2 (cPLA2) was enhanced after incubation of platelets with T2D TGRL and thrombin (+87% and +32%, respectively, P < 0.05) compared with platelets incubated with thrombin only. CONCLUSION: Large TGRL from fasting T2D patients may play a role in the development of atherothrombosis by increasing platelet aggregation and activating the platelet AA signaling pathway.

Management of X-linked adrenoleukodystrophy in Morocco: actual situation.

OBJECTIVES: X-linked adrenoleukodystrophy is a neurodegenerative disorder caused by mutations in the ABCD1 gene. Adrenomyeloneuropathy and childhood cerebral Adrenoleukodystrophy are the most common phenotypes. This paper focuses on a descriptive study of the first program of diagnosis, treatment, and follow-up of this disease in Morocco. RESULTS: We developed three protocols of X-linked Adrenoleukodystrophy management: general protocol, asymptomatic protocol, and heterozygous protocol. Over a period of 5 years, we recruited eight families with 16 patients. Clinically, the presentation is primary adrenal insufficiency and behavioral changes. All patients had elevated levels of very long fatty acids. This is the first study of X-linked adrenoleukodystrophy in Morocco. It shows the importance of this metabolic disease and broadens perspectives in terms of its diagnosis and its treatment.

Whole-exome sequencing improves the diagnosis yield in sporadic infantile spasm syndrome.

Infantile spasms syndrome (ISs) is characterized by clinical spasms with ictal electrodecrement, usually occurring before the age of 1 year and frequently associated with cognitive impairment. Etiology is widely heterogeneous, the cause remaining elusive in 40% of patients. We searched for de novo mutations in 10 probands with ISs and their parents using whole-exome sequencing (WES). Patients had neither consanguinity nor family history of epilepsy. Common causes of ISs were excluded by brain magnetic resonance imaging (MRI), metabolic screening, array-comparative genomic hybridization (CGH) and testing for mutations in CDKL5, STXBP1, and for ARX duplications. We found a probably pathogenic mutation in four patients. Missense mutations in SCN2A (p.Leu1342Pro) and KCNQ2 (p.Ala306Thr) were found in two patients with no history of epilepsy before the onset of ISs. The p.Asn107Ser missense mutation of ALG13 had been previously reported in four females with ISs. The fourth mutation was an in-frame deletion (p.Phe110del) in NR2F1, a gene whose mutations cause intellectual disability, epilepsy, and optic atrophy. In addition, we found a possibly pathogenic variant in KIF3C that encodes a kinesin expressed during neural development. Our results confirm that WES improves significantly the diagnosis yield in patients with sporadic ISs.

[Do we need congenital adrenal hyperplasia screening for premature infants?]. / Faut-il maintenir un dépistage de l'hyperplasie congénitale des surrénales pour les prématurés ?

Congenital adrenal hyperplasia neonatal screening has been introduced in France since 1995. A recent survey has questioned its relevance in premature infants because of a high number of false positives and a low positive predictive value of 17-hydroxyprogesterone dosage. A workgroup at the French screening association (Association française de dépistage et de prévention des handicaps de l'enfant) collected all the epidemiological, clinical and biological data of premature children presenting with adrenal hyperplasia from the national cohort. Their results were compared with those of healthy premature children. All the data showed that the screening in children born before 32 weeks of gestational age is irrelevant, but that it is efficient after this term. A pilot study has been implemented in population to evaluate the opportunity to discontinue this screening in extreme preterm neonates.

Creatine deficiency syndrome. A treatable myopathy due to arginine-glycine amidinotransferase (AGAT) deficiency.

We report two sisters, aged 11 and 6years, with AGAT deficiency syndrome (OMIM 612718) which is the least common creatine deficiency syndrome. They were born full-term to consanguineous parents and had moderate developmental delay. Examination showed an important language delay, a progressive proximal muscular weakness in the lower limbs with Gowers sign and myopathic electromyography. Investigations revealed undetectable guanidinoacetate and low level of creatine in plasma and urine, characteristic findings of AGAT deficiency syndrome. Brain magnetic resonance spectroscopy showed a markedly reduced level of creatine. Guanidinoacetate methyltransferase (GATM) gene sequencing revealed a homozygous missense mutation in exon 4:c.608A>C, (p.Tyr203Ser). Thirteen months after beginning the treatment with oral creatine monohydrate 200mg/kg/day, then 400mg/kg/day, there was a dramatic improvement in muscle strength with Gowers sign disappearance in both patients, and a mild improvement in language and cognitive functions. AGAT deficiency syndrome should be considered in all patients with language retardation and cognitive impairment associated to a myopathy of unknown etiology such that early diagnosis must lead to creatine supplementation to cure the myopathy and improve language and cognitive function.

Phenotype and genotype in 101 males with X-linked creatine transporter deficiency.

BACKGROUND: Creatine transporter deficiency is a monogenic cause of X-linked intellectual disability. Since its first description in 2001 several case reports have been published but an overview of phenotype, genotype and phenotype--genotype correlation has been lacking. METHODS: We performed a retrospective study of clinical, biochemical and molecular genetic data of 101 males with X-linked creatine transporter deficiency from 85 families with a pathogenic mutation in the creatine transporter gene (SLC6A8). RESULTS AND CONCLUSIONS: Most patients developed moderate to severe intellectual disability; mild intellectual disability was rare in adult patients. Speech language development was especially delayed but almost a third of the patients were able to speak in sentences. Besides behavioural problems and seizures, mild to moderate motor dysfunction, including extrapyramidal movement abnormalities, and gastrointestinal problems were frequent clinical features. Urinary creatine to creatinine ratio proved to be a reliable screening method besides MR spectroscopy, molecular genetic testing and creatine uptake studies, allowing definition of diagnostic guidelines. A third of patients had a de novo mutation in the SLC6A8 gene. Mothers with an affected son with a de novo mutation should be counselled about a recurrence risk in further pregnancies due to the possibility of low level somatic or germline mosaicism. Missense mutations with residual activity might be associated with a milder phenotype and large deletions extending beyond the 3' end of the SLC6A8 gene with a more severe phenotype. Evaluation of the biochemical phenotype revealed unexpected high creatine levels in cerebrospinal fluid suggesting that the brain is able to synthesise creatine and that the cerebral creatine deficiency is caused by a defect in the reuptake of creatine within the neurones.

[Medium-chain acyl-CoA-dehydrogenase (MCAD) deficiency: French consensus for neonatal screening, diagnosis, and management]. / Déficit en acyl-CoA-déshydrogénase des acides gras à chaîne moyenne (MCAD): consensus français pour le dépistage, le diagnostic, et la prise en charge.

MCAD deficiency is the most common fatty acid oxidation disorder, with the prevalence varying from 1/10,000 to 1/27,000 in the countries adjacent to France. As the High Authority for Health has recently proposed including MCAD deficiency in the panel of diseases neonatally screened for in France, a consensus was written for the management of MCAD deficiency diagnosed either clinically or by neonatal screening. Patients may present acutely with hyperammonemia, hypoglycemia, encephalopathy, and hepatomegaly, mainly after a prolonged fast of intercurrent infection. Sudden death related to heartbeat disorders may also occur. The diagnosis of MCAD deficiency is suspected on the plasma acylcarnitine and/or the urinary organic acid profile. The diagnosis is confirmed by molecular biology and the enzymatic activity for patients who are not homozygous for the main mutation c.985A>G. However, some MCAD-deficient individuals may remain asymptomatic throughout life. The mainstay of treatment consists in avoiding prolonged fast and prescribing l-carnitine for patients who exhibit a deficiency in plasma carnitine. This management has radically modified the natural history of MCAD deficiency. This consensus will allow homogeneous management of these patients once the neonatal screening of MCAD deficiency has been introduced in France.

Genetic heterogeneity of the GLDC gene in 28 unrelated patients with glycine encephalopathy.

Glycine encephalopathy, or nonketotic hyperglycinaemia (NKH; Mckusick 238300) is a severe autosomal recessive disease due to a defect in the glycine cleavage system (GCS), which is a complex of four subunits: P-, T-, H- and L-proteins. A P-protein (glycine decarboxylase or GLDC) deficiency was reported in about 80% of NKH patients. We performed mutation analysis of the complete coding sequence of the GLDC gene in 28 unrelated patients with neonatal NKH using denaturing high-performance liquid chromatography (DHPLC) and sequencing. Forty different gene alterations were identified, confirming the large molecular heterogeneity of the GLDC gene. Eighteen alterations were clearly disease-causing: two large deletions, four one-base deletions (c.28delC, c.1175delC, c.2186delC, c.2422delA), one 1-base insertion (c.1002_1003insT), one 4-base insertion (c.1285_1286insCAAA), one insertion/deletion (c.2153_2155delinsTCCTGGTTTA), five nonsense mutations (p.E153X, p.R236X, p.E270X, p.R337X, p.R424X) and four splice site mutations (c.861+1G > T, c.1402-1C > G, c.2316-1G > A, c.2919+1G > A). Additionally, we identified one intronic mutation outside the consensus splice sites (c.2838+5G > A) and 21 nucleotide substitutions leading to amino acid change (including three previously described mutations: p.T269M, p.R461Q, p.G771R), the pathogenicity of which should be confirmed by expression studies (p.S132W, p.Y138F, p.G171A, p.T187K, p.R212K, p.T269M, p.R373W, p.I440N, p.R461Q, p.N533Y, p.C644F, p.H651R, p.V705M, p.N732K, p.G771R, p.H775R, p.T830M, p.A841P, p.D880V, p.S957P and p.R966G). Mutation analysis allowed us to identify sequence alterations in both alleles for 19 patients and in one allele for 7 patients One patient was carrying three mutations (p.Y138F, p.T269M and p.E153X) and one patient was carrying two amino acid substitutions on the same allele (p.V705M and p.R212K) and an unidentified mutation on the other allele. No mutation could be found in two patients, suggesting possible defects in the H-protein or gene alterations that could not be identified by our technique. The potential use of genotype determination for prenatal diagnosis is emphasized.

Clinical, morphological, and molecular aspects of sialic acid storage disease manifesting in utero.

BACKGROUND: Sialic acid storage diseases (SASDs) are caused by the defective transport of free sialic acid outside the lysosome. Apart from the Salla presentation in Finland, SASD is a very rare form of lysosomal storage disease (LSD) with approximately 35 cases, all diagnosed after birth, having been reported worldwide. We report a series of 12 French patients with very early manifestations, including eight fetuses diagnosed in utero. RESULTS: Ultrasound examination, fetal autopsy, or clinical examination showed prominent ascites, rarely progressing to complete hydrops, and highlighted the early severity of bone disease. Dramatic increase of free sialic acid in various biological samples confirmed the diagnosis in all cases. Storage staining affinities and storage distribution in placenta and fetal organs allowed differential diagnosis from other LSDs but cannot differentiate between SASD, sialidosis, and galactosialidosis. Fourteen different mutations were identified, showing the molecular heterogeneity of SASD in the French population. We found that the previously described p.Y306X mutation generated two different transcripts, and we identified seven novel mutations: three deletions (del exon 7, del exons10+11 and c.1296delT), one splice site mutation (c.1350+1G-->T) one nonsense mutation (p.W339X), and two missense mutations (p.R57C and p.G127E). CONCLUSIONS: The severity of our patients' genotypes is in agreement with their phenotypes but not with the importance and early appearance of the very frequent in utero manifestations. Minimal fetal disease in some patients and a reported case of heterogeneity of fetal involvement within a family suggest that factors other than the genotype influence fetal manifestations.

[Creatine deficiency syndromes]. / Les syndromes de déficit en créatine.

INTRODUCTION: Creatine deficiency syndromes are a newly described group of inborn errors of metabolism affecting creatine metabolism. Three diseases have been described: deficiency of arginine: glycine amidinotransferase (AGAT), deficiency of guanidinoacetate methyltransferase (GAMT) and creatine transporter defect (CRTR). STATE OF ART: These syndromes are characterized by a depletion of creatine/phosphocreatine in the brain. Clinically, most of the patients develop a variable mental retardation and a severe speech delay associated with epilepsy, extra-pyramidal syndrome and behavior disturbances. These diseases are often diagnosed during infancy but a few adult cases have been reported recently. Diagnosis is established by measurement of guanidinoacetate and creatine in biologic fluids and in vivo proton magnetic resonance spectroscopy by the total lack of intra-cerebral creatine/phosphocreatine demonstrating. GAMT and AGAT deficiencies are treatable by oral creatine supplementation whereas patients with CRTR do not respond to the treatment. CONCLUSION: Better knowledge of these syndromes is necessary to optimize diagnosis and patient management of these rare but potentially treatable disorders.

False-positive results in neonatal screening for cystic fibrosis based on a three-stage protocol (IRT/DNA/IRT): Should we adjust IRT cut-off to ethnic origin?

Since 1979, newborn screening for cystic fibrosis (CF) has been possible by measuring immunoreactive tryspinogen (IRT) in blood spots. In France, a programme based on a three-stage strategy (IRT/DNA/IRT) started in 2002. In the Rhône-Alpes area, the positive screening rate (i.e. the proportion of samples sent for genotyping) observed after the first IRT measurement was higher than the expected rate (0.65% versus 0.50%), without a greater CF incidence. We hypothesized that the IRT reference range could differ according to the ethnic origin of the newborns. 35 141 newborns were studied and divided into two groups: European ethnic group 26 324 (75%) and North African ethnic group 8817 (25%). 243 positive newborns were identified: 146 (60%) in the European ethnic group and 97 (40%) in the North African ethnic group. Three CF patients and 11 unaffected heterozygotes were found in the European group, but no mutations were found in the North African group. Mean IRT values and the percentage of IRT values over the cut-off were significantly higher in the North African group than in the European group (mean IRT = 21.17 microg/L and 19.74 microg/L, p < 0.0001; %IRT > cut-off = 1.1% and 0.5%, respectively). For the positive screened newborns, term and IRT mean were comparable, whereas birth weight was higher in the North African ethnic group. These results lead us to conclude that (i) newborns from families of North African origin have higher IRT values and (ii) most of the positive screened newborns in this population could be considered as 'false positives'. These conclusions could explain, in part, the large variations seen in the positive screening rate in the French CF neonatal screening and raise the question whether it is relevant to adapt cut-off to ethnic origin of the newborns.

[Should blood samples be drawn on heparin-anticoagulant for lipid analysis?]. / Peut-on prélever le bilan lipidique sur héparine?

Lipid profile is often performed on heparinized-plasma because nothing in particular is explained in the technical data sheet about anticoagulant and because few data (mainly with EDTA anticoagulant) are available in literature. In order to evaluate heparinized-plasma vs serum differences, 50 normo- or hyperlipidemic samples were collected and assayed in 3 clinical laboratories in Lyon on Hitachi analysers with Roche Diagnostic reagents. Lipid values are lower in plasma than in serum; the average negative bias for cholesterol levels is 2 to 4,5% and for triglycerides about 3%, depending on the laboratory; the effect on HDL-cholesterol values is not significant. These results were confirmed by manual procedure on 28 samples with Roche Diagnostic reagent and two similar other reagents (Biomerieux and Randox). A negative bias of 4% on total cholesterol and triglycerides levels is not very important for clinical diagnosis but it is more serious for LDL-cholesterol estimated with Friedewald equation; LDL-cholesterol value needs accuracy because it is a therapeutic goal with statin therapy and an high negative bias (until 0,70 g/L in our results) is unacceptable; moreover, there is a real risk of providing false total cholesterol results. Therefore it is essential to collect blood for lipid profile without any anticoagulant.

[Application of tandem mass spectrometry to neonatal screening of inherited metabolic diseases: focus on present developments]. / La spectrométrie de masse en tandem appliquée au dépistage néonatal des maladies héréditaires du métabolisme: le point sur les utilisations actuelles.

The recent evolution of tandem mass spectrometry allows to diagnose more than twenty inherited metabolic diseases within a single blood spot. Nowadays, it is technically possible to screen newborns for most of fatty acid oxidation, organic acid and amino acid disorders. An important number of prospective pilot studies, using tandem mass spectrometry, have been done worldwide. However, several technical, economical, medical and ethical problems are raised by these applications. This review is intended to focus on this technology and to resume results from the main international studies.

CDG IIx with unusual phenotype.

Congenital disorders of glycosylation (CDG) are a group of genetic diseases characterized by defective protein glycosylation. N-glycosylation defects are divided into two groups (I and II). CDG group II (types IIa to IIe) refers to defects in the Golgi processing of protein-bound glycans. We report a patient with CDG IIx and an unusual phenotype.