Association of elevated neonatal thyroid-stimulating hormone levels with school performance and stimulant prescription for attention deficit hyperactivity disorder in childhood.

Untreated severe newborn thyroid deficiency causes neurocognitive impairment; however, the impact of mild thyroid deficiency is not known. This study aimed to examine whether mildly elevated neonatal thyroid-stimulating hormone (TSH) levels are associated with poor school performance or stimulant prescription for attention deficit hyperactivity disorder (ADHD). This record-linkage study included 232,790 term-born infants in Australia with a TSH level below newborn screening threshold (< 15 mIU/L). Among our cohort, as TSH levels increased, the proportion of infants born low birthweight via caesarean section and with disadvantaged socioeconomic status increased. Multivariable logistic regression analysis showed that, compared with infants with 'normal' neonatal TSH level (< 5 mIU/L), those with neonatal TSH 10-15 mIU/L had an increased risk of being exempt from school testing (aOR 1.63 (95% CI 1.06-2.69)) or prescribed a stimulant for ADHD (aOR 1.57 (95% CI 1.10-2.24)), adjusted for perinatal and sociodemographic factors. Among a nested analysis of 460 sibling pairs, siblings with 'mildly elevated' TSH levels were more likely to be exempt from school tests compared with siblings with normal TSH levels (aOR 2.53, 95% CI 1.01-6.33).Conclusion: In this population cohort and sibling analysis, mildly elevated neonatal TSH levels were associated with being exempt from school testing due to significant or complex disability. What is Known: • Newborn screening for severe thyroid hormone deficiency has virtually eliminated congenital hypothyroidism-associated intellectual disability in developed countries. • The impact of mild thyroid hormone deficiency in infants is unclear. What is New: • Children with a mildly elevated neonatal TSH level below current newborn screening cut-offs have an increased likelihood of being exempt from school testing due to significant or complex disability compared with siblings and peers. This study includes a population-based and nested sibling analysis.

A founder mutation in PET100 causes isolated complex IV deficiency in Lebanese individuals with Leigh syndrome.

Leigh syndrome (LS) is a severe neurodegenerative disorder with characteristic bilateral lesions, typically in the brainstem and basal ganglia. It usually presents in infancy and is genetically heterogeneous, but most individuals with mitochondrial complex IV (or cytochrome c oxidase) deficiency have mutations in the biogenesis factor SURF1. We studied eight complex IV-deficient LS individuals from six families of Lebanese origin. They differed from individuals with SURF1 mutations in having seizures as a prominent feature. Complementation analysis suggested they had mutation(s) in the same gene but targeted massively parallel sequencing (MPS) of 1,034 genes encoding known mitochondrial proteins failed to identify a likely candidate. Linkage and haplotype analyses mapped the location of the gene to chromosome 19 and targeted MPS of the linkage region identified a homozygous c.3G>C (p.Met1?) mutation in C19orf79. Abolishing the initiation codon could potentially still allow initiation at a downstream methionine residue but we showed that this would not result in a functional protein. We confirmed that mutation of this gene was causative by lentiviral-mediated phenotypic correction. C19orf79 was recently renamed PET100 and predicted to encode a complex IV biogenesis factor. We showed that it is located in the mitochondrial inner membrane and forms a ∼300 kDa subcomplex with complex IV subunits. Previous proteomic analyses of mitochondria had overlooked PET100 because its small size was below the cutoff for annotating bona fide proteins. The mutation was estimated to have arisen at least 520 years ago, explaining how the families could have different religions and different geographic origins within Lebanon.

Differences in Outcomes between Early and Late Diagnosis of Cystic Fibrosis in the Newborn Screening Era.

OBJECTIVES: To evaluate children with cystic fibrosis (CF) who had a late diagnosis of CF (LD-CF) despite newborn screening (NBS) and compare their clinical outcomes with children diagnosed after a positive NBS (NBS-CF). STUDY DESIGN: A retrospective review of patients with LD-CF in New South Wales, Australia, from 1988 to 2010 was performed. LD-CF was defined as NBS-negative (negative immunoreactive trypsinogen or no F508del) or NBS-positive but discharged following sweat chloride < 60 mmol/L. Cases of LD-CF were each matched 1:2 with patients with NBS-CF for age, sex, hospital, and exocrine pancreatic status. RESULTS: A total of 45 LD-CF cases were identified (39 NBS-negative and 6 NBS-positive) with 90 NBS-CF matched controls. Median age (IQR) of diagnosis for LD-CF and NBS-CF was 1.35 (0.4-2.8) and 0.12 (0.03-0.2) years, respectively (P <.0001). Estimated incidence of LD-CF was 1 in 45 000 live births. Compared with NBS-CF, LD-CF had more respiratory manifestations at time of diagnosis (66% vs 4%; P <.0001), a higher rate of hospital admission per year for respiratory illness (0.49 vs 0.2; P = .0004), worse lung function (forced expiratory volume in 1 second percentage of predicted, 0.88 vs 0.97; P = .007), and higher rates of chronic colonization with Pseudomonas aeruginosa (47% vs 24%; P = .01). The LD-CF cohort also appeared to be shorter than NBS-CF controls (mean height z-score -0.65 vs -0.03; P = .02). CONCLUSIONS: LD-CF, despite NBS, seems to be associated with worse health before diagnosis and worse later growth and respiratory outcomes, thus providing further support for NBS programs for CF.

Elevated plasma dihydroorotate in Miller syndrome: Biochemical, diagnostic and clinical implications, and treatment with uridine.

BACKGROUND: Miller syndrome (post-axial acrofacial dysostosis) arises from gene mutations for the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH). Nonetheless, despite demonstrated loss of enzyme activity dihydroorotate (DHO) has not been shown to accumulate, but paradoxically urine orotate has been reported to be raised, confusing the metabolic diagnosis. METHODS: We analysed plasma and urine from a 4-year-old male Miller syndrome patient. DHODH mutations were determined by PCR and Sanger sequencing. Analysis of DHO and orotic acid (OA) in urine, plasma and blood-spot cards was performed using liquid chromatography-tandem mass spectrometry. In vitro stability of DHO in distilled water and control urine was assessed for up to 60h. The patient received a 3-month trial of oral uridine for behavioural problems. RESULTS: The patient had early liver complications that are atypical of Miller syndrome. DHODH genotyping demonstrated compound-heterozygosity for frameshift and missense mutations. DHO was grossly raised in urine and plasma, and was detectable in dried spots of blood and plasma. OA was raised in urine but undetectable in plasma. DHO did not spontaneously degrade to OA. Uridine therapy did not appear to resolve behavioural problems during treatment, but it lowered plasma DHO. CONCLUSION: This case with grossly raised plasma DHO represents the first biochemical confirmation of functional DHODH deficiency. DHO was also easily detectable in dried plasma and blood spots. We concluded that DHO oxidation to OA must occur enzymatically during renal secretion. This case resolved the biochemical conundrum in previous reports of Miller syndrome patients, and opened the possibility of rapid biochemical screening.

Chaperone therapy for homocystinuria: the rescue of CBS mutations by heme arginate.

Classical homocystinuria is caused by mutations in the cystathionine ß-synthase (CBS) gene. Previous experiments in bacterial and yeast cells showed that many mutant CBS enzymes misfold and that chemical chaperones enable proper folding of a number of mutations. In the present study, we tested the extent of misfolding of 27 CBS mutations previously tested in E. coli under the more folding-permissive conditions of mammalian CHO-K1 cells and the ability of chaperones to rescue the conformation of these mutations. Expression of mutations in mammalian cells increased the median activity 16-fold and the amount of tetramers 3.2-fold compared with expression in bacteria. Subsequently, we tested the responses of seven selected mutations to three compounds with chaperone-like activity. Aminooxyacetic acid and 4-phenylbutyric acid exhibited only a weak effect. In contrast, heme arginate substantially increased the formation of mutant CBS protein tetramers (up to sixfold) and rescued catalytic activity (up to ninefold) of five out of seven mutations (p.A114V, p.K102N, p.R125Q, p.R266K, and p.R369C). The greatest effect of heme arginate was observed for the mutation p.R125Q, which is non-responsive to in vivo treatment with vitamin B(6). Moreover, the heme responsiveness of the p.R125Q mutation was confirmed in fibroblasts derived from a patient homozygous for this genetic variant. Based on these data, we propose that a distinct group of heme-responsive CBS mutations may exist and that the heme pocket of CBS may become an important target for designing novel therapies for homocystinuria.

Fifty years of newborn screening.

Newborn screening has evolved fast following recent advances in diagnosis and treatment of disease, particularly the development of multiplex testing and applications of molecular testing. Formal evidence of benefit from newborn screening has been largely lacking, due to the rarity of individual disorders. There are wide international differences in the choice of disorders screened, and ethical issues in both screening and not screening are apparent. More evidence is needed about benefit and harm of screening for specific disorders and renewed discussion about the basic aims of newborn screening must be undertaken.

Using record linkage to investigate perinatal factors and neonatal thyroid-stimulating hormone.

AIM: Studies examining the relationship between maternal and infant thyroid parameters have shown conflicting results. Record linkage provides an opportunity to examine the association between maternal and infant thyroid-stimulating hormone (TSH) levels. Our aim was to demonstrate the feasibility of record linkage of newborn screening (NBS), laboratory and birth databases for research by investigating the association between maternal and newborn TSH levels. METHODS: The records of 2802 women with first trimester serum TSH concentrations were linked with population-based birth data and NBS data containing infant TSH levels. Association between moderately high neonatal TSH levels (>5 mIU/L) and maternal and infant characteristics was evaluated. The correlation and association between maternal and infant TSH levels were assessed using Pearson's correlation coefficient and multivariable linear regression, respectively. RESULTS: Of maternal and birth records, 99.3% linked with an NBS record. Mother's country of birth, gestational age (>41 weeks) and lower birthweight were associated with neonatal TSH levels >5 mIU/L. Neonatal and maternal first trimester TSH levels were not correlated, although statistically significant (r = 0.05, P = 0.008). The association between neonatal TSH and maternal TSH, after adjusting for maternal age, gestational age and age at NBS testing, was also small (b = 0.039, P = 0.009). CONCLUSIONS: Record linkage is a feasible and cost-efficient way to investigate the association between maternal factors and neonatal hormone levels. First trimester maternal thyroid levels are not correlated with neonatal TSH levels. This method of outcome assessment can be used for future research examining long-term outcomes for infants with different NBS results.

Expanded newborn screening in New South Wales: missed cases.

There have been few reports of cases missed by expanded newborn screening. Tandem mass spectrometry was introduced in New South Wales, Australia in 1998 to screen for selected disorders of amino acid, organic acid and fatty acid metabolism. Of 1,500,000 babies screened by 2012, 1:2700 were diagnosed with a target disorder. Fifteen affected babies were missed by testing, and presented clinically or in family studies. In three cases (cobalamin C defect, very-long-chain acyl-CoA dehydrogenase deficiency and glutaric aciduria type 1), this led to modification of analyte cut-off values or protocols during the first 3 years. Two patients with intermittent MSUD, two with ß-ketothiolase deficiency, two with citrin deficiency, two siblings with arginosuccinic aciduria, two siblings with homocystinuria, and one with cobalamin C defect had analyte values and ratios below the action limits which could not have been detected without unacceptable false-positive rates. A laboratory interpretation error led to missing one case of cobalamin C defect. Reference ranges, regularly reviewed, were not altered. For citrin deficiency, while relevant metabolites are detectable by tandem mass spectrometry, our cut-off values do not specifically screen for that disorder. Most of the missed cases are doing well and with no acute presentations although eight of 15 are likely to have been somewhat adversely affected by a late diagnosis. Analyte ratio and cut-off value optimisations are important, but for some disorders occasional missed cases may have to be tolerated to maintain an acceptable specificity, and avoid harm from screening.

Maternal attitudes to newborn screening for fragile X syndrome.

Although fragile X syndrome (FXS) is the commonest cause of inherited intellectual disability the mean age of diagnosis in Australia is 5.5 years. Newborn screening for FXS can provide an early diagnosis, preventing the "diagnostic odyssey", allowing access to early interventions, and providing reproductive information for parents. Parents of affected children support newborn screening, but few clinical studies have evaluated community attitudes. A pilot study in 2009-2010 was performed in a tertiary hospital to explore feasibility and maternal attitudes. FXS testing of male and female newborns was offered to mothers in addition to routine newborn screening. Mothers were provided with information about FXS, inheritance pattern, carrier status, and associated adult-onset disorders. One thousand nine hundred seventy-one of 2,094 mothers (94%) consented to testing of 2,000 newborns. 86% completed the attitudinal survey and 10% provided written comments. Almost all parents (99%) elected to be informed of both premutation and full mutation status and there was little concern about identification of carrier status or associated adult-onset disorders. Most mothers (96%) were comfortable being approached in the postnatal period and supported testing because no extra blood test was required. Mothers considered an early diagnosis beneficial to help prepare for a child with additional needs (93%) and for reproductive planning (64%). Some were anxious about the potential test results (10%) and others felt their feelings towards their newborn may change if diagnosed with FXS (16%). High participation rates and maternal attitudes indicate a high level of maternal acceptance and voluntary support for newborn screening for FXS.

Enhanced interpretation of newborn screening results without analyte cutoff values.

PURPOSE: To improve quality of newborn screening by tandem mass spectrometry with a novel approach made possible by the collaboration of 154 laboratories in 49 countries. METHODS: A database of 767,464 results from 12,721 cases affected with 60 conditions was used to build multivariate pattern recognition software that generates tools integrating multiple clinically significant results into a single score. This score is determined by the overlap between normal and disease ranges, penetration within the disease range, differences between conditions, and weighted correction factors. RESULTS: Ninety tools target either a single condition or the differential diagnosis between multiple conditions. Scores are expressed as the percentile rank among all cases with the same condition and are compared to interpretation guidelines. Retrospective evaluation of past cases suggests that these tools could have avoided at least half of 279 false-positive outcomes caused by carrier status for fatty-acid oxidation disorders and could have prevented 88% of known false-negative events. CONCLUSION: Application of this computational approach to raw data is independent from single analyte cutoff values. In Minnesota, the tools have been a major contributing factor to the sustained achievement of a false-positive rate below 0.1% and a positive predictive value above 60%.

Leukoencephalopathies associated with disorders of cobalamin and folate metabolism.

Disorders of cobalamin and folate intracellular metabolism that result in defective remethylation of homocysteine to methionine are associated with leukodystrophy, whereas disorders of cobalamin transport generally are not. Cobalamin derivatives are needed for only two reactions in man; remethylation of homocysteine to methionine, with methylcobalamin as a cofactor for methionine synthase, and the conversion of methylmalonyl-coenzyme A to succinyl coenzyme A by methylmalonyl-CoA mutase, with adenosylcobalamin as a cofactor. Mutations at various metabolic steps affect the synthesis of adenosylcobalamin (CblA, CblB, and CblD2), methylcobalamin (CblE, CblG, and CblD1), or both of these (CblF, CblD, and CblC). The most common disorder of folate metabolism, 5,10-methylenetetrahydrofolate deficiency, also affects remethylation and presents with leukodystrophy. Pathways of cobalamin and folate metabolism intersect at one site, methionine synthase. Patients with the remethylating disorders present acutely or chronically with significant neurologic, hematologic, vascular, and other symptoms. Circulating levels of cobalamin and folate are usually normal in these disorders, and initial diagnosis is aided by measurement of homocysteine and methylmalonic acid in blood or urine, together with hematologic tests. Current diagnosis is often by newborn screening. These disorders all show autosomal recessive inheritance, and all are treatable, although with variable outcome.

Newborn screening: how are we travelling, and where should we be going?

In general, newborn screening is now a highly successful enterprise. The introduction of tandem mass spectrometry in the mid-1990s changed the pace of screening, raising its profile and increasing its relevance to a wider range of health professionals. The clinical effectiveness is not in doubt for some conditions, but is lacking for others. Evaluation has major difficulties for the rarer disorders and has been sadly neglected. Partly because clinical effectiveness has not been enthusiastically addressed, but also because of undue caution on the part of regulators, who often seem to ignore available evidence, there are huge differences in the adoption of screening programmes in different jurisdictions. New treatments, especially mutation-specific treatments, and technological advances in diagnostic testing are being rapidly developed, and this will further change the face of newborn screening and probably magnify these differences. The challenges will be considerable, especially with the increasing availability of DNA testing at modest cost. It is likely that there will be pressure to change the aims of newborn screening to encompass "personalised medicine". We must all prepare in a thoughtful way for these future challenges.

Newborn screening for congenital hypothyroidism in very-low-birth-weight babies: the need for a second test.

BACKGROUND: Very-low-birth-weight babies (VLBW) with hypothyroidism may show a delayed postnatal rise in thyroid stimulating hormone (TSH), mainly due to immaturity of the hypothalamic-pituitary-thyroid axis. Transient hypothyroidism is prevalent in VLBW babies and some affected babies are considered to need treatment. There is disagreement about whether a second screening test is needed in VLBW babies to detect all cases that need treatment. METHODS: We included in the study all babies with a birth weight ≤ 1,500 g born in New South Wales and the Australian Capital Territory between January 2006 and December 2008. Newborn screening samples for TSH measurement were taken in the first days of life and again at 1 month. During week 1, a blood-spot TSH level of ≥20 mIU/L was considered positive, and at 1 month a positive level was ≥7 mIU/L, and triggered full investigation. RESULTS: In the cohort of 301,000 babies, 2,313 VLBW babies survived for testing, and 2,117 repeat screening samples were received. Forty-three babies had transient hypothyroidism, with thyroid function normalising before 2 months of age, usually without treatment. Eighteen babies required treatment beyond 2 months of age (1:128 of surviving babies), 16 having had normal TSH results on initial testing, and 12 having levels below 6 mIU/L. CONCLUSION: Significant hypothyroidism, transient or permanent, but persisting beyond 2 months of age is common in VLBW babies. There is a delayed rise in TSH in some, and secondary screening at 1 month of age detects babies deemed by local paediatric endocrinologists as needing treatment.

Diagnosis and management of glutaric aciduria type I--revised recommendations.

Glutaric aciduria type I (synonym, glutaric acidemia type I) is a rare organic aciduria. Untreated patients characteristically develop dystonia during infancy resulting in a high morbidity and mortality. The neuropathological correlate is striatal injury which results from encephalopathic crises precipitated by infectious diseases, immunizations and surgery during a finite period of brain development, or develops insidiously without clinically apparent crises. Glutaric aciduria type I is caused by inherited deficiency of glutaryl-CoA dehydrogenase which is involved in the catabolic pathways of L-lysine, L-hydroxylysine and L-tryptophan. This defect gives rise to elevated glutaric acid, 3-hydroxyglutaric acid, glutaconic acid, and glutarylcarnitine which can be detected by gas chromatography/mass spectrometry (organic acids) or tandem mass spectrometry (acylcarnitines). Glutaric aciduria type I is included in the panel of diseases that are identified by expanded newborn screening in some countries. It has been shown that in the majority of neonatally diagnosed patients striatal injury can be prevented by combined metabolic treatment. Metabolic treatment that includes a low lysine diet, carnitine supplementation and intensified emergency treatment during acute episodes of intercurrent illness should be introduced and monitored by an experienced interdisciplinary team. However, initiation of treatment after the onset of symptoms is generally not effective in preventing permanent damage. Secondary dystonia is often difficult to treat, and the efficacy of available drugs cannot be predicted precisely in individual patients. The major aim of this revision is to re-evaluate the previous diagnostic and therapeutic recommendations for patients with this disease and incorporate new research findings into the guideline.

Tyrosine hydroxylase deficiency: a treatable disorder of brain catecholamine biosynthesis.

Tyrosine hydroxylase deficiency is an autosomal recessive disorder resulting from cerebral catecholamine deficiency. Tyrosine hydroxylase deficiency has been reported in fewer than 40 patients worldwide. To recapitulate all available evidence on clinical phenotypes and rational diagnostic and therapeutic approaches for this devastating, but treatable, neurometabolic disorder, we studied 36 patients with tyrosine hydroxylase deficiency and reviewed the literature. Based on the presenting neurological features, tyrosine hydroxylase deficiency can be divided in two phenotypes: an infantile onset, progressive, hypokinetic-rigid syndrome with dystonia (type A), and a complex encephalopathy with neonatal onset (type B). Decreased cerebrospinal fluid concentrations of homovanillic acid and 3-methoxy-4-hydroxyphenylethylene glycol, with normal 5-hydroxyindoleacetic acid cerebrospinal fluid concentrations, are the biochemical hallmark of tyrosine hydroxylase deficiency. The homovanillic acid concentrations and homovanillic acid/5-hydroxyindoleacetic acid ratio in cerebrospinal fluid correlate with the severity of the phenotype. Tyrosine hydroxylase deficiency is almost exclusively caused by missense mutations in the TH gene and its promoter region, suggesting that mutations with more deleterious effects on the protein are incompatible with life. Genotype-phenotype correlations do not exist for the common c.698G>A and c.707T>C mutations. Carriership of at least one promotor mutation, however, apparently predicts type A tyrosine hydroxylase deficiency. Most patients with tyrosine hydroxylase deficiency can be successfully treated with l-dopa.

Ethical issues in genetics.

Genetic disorders are caused by abnormalities in genes and chromosomes and for the most part have implications for family members, affecting such matters as confidentiality and disclosure to third parties. Genetic testing can be not only diagnostic but also predictive, raising issues of the need for pre-test counselling, protection of children from unwanted testing, and most importantly, the imprecision of interpretation of future risk. The rise in availability of direct-to-consumer testing is a fresh cause for concern, as are the new possibilities in reproductive medicine. New technologies and the falling cost of whole genome sequencing ensure that ethics will be a prominent concern for clinical genetics.