Interference of ketone bodies on laboratory creatinine measurement in children with DKA: a call for change in testing practices.

BACKGROUND: The presence of ketone bodies (KBs) can interfere with creatinine (Cr) measurement in both enzymatic and Jaffe methods. Since a high proportion of children hospitalized for diabetic ketoacidosis (DKA) develop acute kidney injury (AKI), here we investigate whether KB interferences affect the accuracy of pediatric Cr measurement. METHODS: Residual patient plasma samples were pooled to make three Cr levels (~ 50, 100, and 250 µM). KBs (acetone, acetoacetate, and ß-hydroxybutyrate) were used to spike the pooled samples. All samples were measured for Cr by two enzymatic methods (E1 and E2), two Jaffe methods (J1 and J2), and LC-MS/MS. LC-MS/MS was considered the gold standard, and the % difference in Cr concentration was calculated for each method. RESULTS: E1 and E2 were unaffected by the presence of all three KBs. J1 and J2 were unaffected by the presence of ß-hydroxybutyrate. The presence of acetone resulted in dose-dependent positive interference in both Jaffe methods, whereas the presence of acetoacetate resulted in dose-dependent positive and negative interference in J1 and J2, respectively. CONCLUSIONS: Compared to the enzymatic methods, the Jaffe methods were much more susceptible to interference by acetone and acetoacetate, especially at lower Cr values which are commonly seen in pediatrics. Interpretation of changes in Cr concentration between different hospitals when transferring patients can become ambiguous and true kidney function unclear if different methods are used without awareness of method-specific biases. To improve DKA patient care, we recommend standardizing all of the Cr methods to an enzymatic method. A higher resolution version of the Graphical abstract is available as Supplementary information.

Maternal vitamin B12 status in early pregnancy and its association with birth outcomes in Canadian mother-newborn Dyads.

Vitamin B12 (B12) is a co-enzyme essential for fetal growth and development. Lower maternal B12 status has been associated with preterm birth (<37 gestational weeks) and low birth weight (<2500 g), which are linked to morbidity and mortality across the lifespan. In Canada, 17-25 % of women in early pregnancy had a serum total B12 concentration <148 pmol/l and maternal total B12 concentration decreased throughout pregnancy. This study aimed to determine the association between maternal B12 status and birth outcomes in Canadian mother-newborn dyads. A secondary analysis of 709 mother-newborn dyads in British Columbia (BC), Canada, was conducted. Bio-banked first- (n 656) and second-trimester (n 709) maternal serum samples of apparently healthy South Asian (50 %) and European (50 %) women from the BC Prenatal Genetic Screening Program were quantified for B12 biomarkers (total B12, holotranscobalamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy)). Obstetric history and birth outcome data were obtained from the BC Perinatal Data Registry. All associations were determined using multiple linear regression. Maternal serum total B12, holoTC, MMA and tHcy had a mean weekly decrease of 3·64 pmol/l, 1·04 pmol/l, 1·44 nmol/l and 0·104 µmol/l, respectively (P < 0·001). Despite a total B12 concentration <148 pmol/l among 20-25 % of the women, maternal B12 biomarker concentrations were not associated with birth weight z-score, head circumference z-score and gestational age at birth (P > 0·05). Additional research in women at high risk of adverse birth outcomes and the association between maternal B12 status and functional, for example, cognitive, outcomes is needed.

Investigating oxythiamine levels in children undergoing kidney transplantation and the risk of immediate post-operative metabolic and hemodynamic decompensation.

BACKGROUND: Oxythiamine is a uremic toxin that acts as an antimetabolite to thiamine and has been associated with cases of Shoshin beriberi syndrome in adults. We sought to identify whether surgical stress and ischemia/reperfusion injury may precipitate functional thiamine deficiency in children peritransplant. METHODS: We retrospectively analyzed a cohort of pediatric kidney transplant recipients. Oxythiamine levels were measured in pre-transplant serum samples by mass spectrometry and tested for association with severity of lactic acidosis in the first 24 h post-transplant. Secondary outcomes included association with hyperglycemia and indicators of dialysis adequacy (DA). RESULTS: Forty-seven patients were included in the analysis. Median oxythiamine levels differed by modality, measuring 0.67 nM (IQR 0.31, 0.74), 0.34 nM (IQR 0.28, 0.56), and 0.25 nM (IQR 0.17, 0.38) for peritoneal dialysis (PD), hemodialysis (HD), and no dialysis, respectively (p = 0.05). Oxythiamine was associated with 24-h lactate levels (r = 0.38, p = 0.02) and negatively associated with DA (r = - 0.44, p = 0.02). Median oxythiamine levels were higher in patients with poor DA (0.92 nM (IQR 0.51, 1.01) vs. 0.40 nM (IQR 0.24, 0.51), p < 0.01). Sensitivity analysis showed absence of residual association of oxythiamine with 24-h lactate or dialysis modality, but remained significant for DA (p = 0.03). One patient manifested Shoshin beriberi syndrome (oxythiamine 2.03 nM). CONCLUSIONS: Oxythiamine levels are associated with DA at transplant. Patients on PD with no residual kidney function and low DA manifest the highest oxythiamine levels and may be at an increased risk for developing acute Shoshin beriberi syndrome in the early post-transplant period.

Diagnostic yield from routine metabolic screening tests in evaluation of global developmental delay and intellectual disability.

Global developmental delay and intellectual disability (GDD/ID) affect 3% of the paediatric population. Although inborn errors of metabolism (IEM) are not a common cause of GDD/ID, early therapeutic intervention can improve neurodevelopmental manifestations. In 2012, a first-tier test panel, including specialized metabolic and routine chemistry tests, was piloted to community-based paediatricians in British Columbia with aims to achieve earlier diagnosis of treatable IEM. OBJECTIVE: The aim of this retrospective review was to evaluate the diagnostic yield from these first-tier tests in the 7 years before (2006 to 2012) and after (2013 to 2019) implementation at the community paediatrician level. RESULTS: Prior and postimplementation diagnostic yield of an IEM from first-tier metabolic testing was 9 out of 986 (0.91%) and 11 out of 4,345 children (0.25%), respectively. Disorders of creatine metabolism and organic acidurias were the most frequently established diagnoses in both time periods. No diagnoses were established through acylcarnitine copper/ceruloplasmin, lactate, or ammonia testing. Twenty out of 24 patients had specific neurological or other red flag signs in addition to GDD/ID. Four boys diagnosed with an x-linked creatine transporter defect (CTD) had speech-language delay as the most prominent finding. CONCLUSIONS: The expansion of first-tier metabolic testing to community-based paediatricians in BC did not yield an increase in IEM diagnoses. A modified first-tier test panel should be offered to patients with GDD/ID, neurologic, and/or red flag signs. Urine creatine testing in boys with speech-language delay warrants consideration to detect CTD.

Clinical Impact and Cost Efficacy of Newborn Screening for Congenital Adrenal Hyperplasia.

OBJECTIVES: To evaluate the clinical impact of a congenital adrenal hyperplasia (CAH) newborn screening program and incremental costs relative to benefits in screened vs unscreened infants. We hypothesized that screening would lead to clinical benefits and would be cost effective. STUDY DESIGN: This was an ambispective cohort study at British Columbia Children's Hospital, including infants diagnosed with CAH from 1988-2008 and 2010-2018. Data were collected retrospectively (unscreened cohort) and prospectively (screened cohort). Outcome measures included hospitalization, medical transport, and resuscitation requirements. The economic analysis was performed using a public payer perspective. RESULTS: Forty unscreened and 17 screened infants were diagnosed with CAH (47% vs 53% male). Median days to positive screen was 6 and age at diagnosis was 5 days (range, 0-30 days) and 6 days (range, 0-13 days) in unscreened and screened populations, respectively. In unscreened newborns, 55% required transport to a tertiary care hospital, 85% required hospitalization, and 35% required a fluid bolus compared with 29%, 29%, and 12% in screened infants, respectively. The cost of care was $33 770 per case in unscreened vs $17 726 in screened newborns. In the screened cohort, the incremental cost-effectiveness ratio was $290 in the best case analysis and $4786 in the base case analysis, per hospital day avoided. CONCLUSIONS: Compared with unscreened newborns, those screened for CAH were less likely to require medical transport and had shorter hospital stays. Screening led to a decrease in hospitalization costs. Although screening did not result in cost savings, it was assessed to be cost effective considering the clinical benefits and incremental cost-effectiveness ratio.

A Pedagogical Approach to Integrative Neuromuscular Training to Improve Motor Competence in Children: A Randomized Controlled Trail.

Font-Lladó, R, López-Ros, V, Montalvo, AM, Sinclair, G, Prats Puig, A, and Fort-Vanmeerhaeghe, A. A pedagogical approach to integrative neuromuscular training to improve motor competence in children: a RCT. J Strength Cond Res 34(11): 3078-3085, 2020-To assess the effectiveness of a pedagogical approach to an integrative neuromuscular training (INT) program as a warm-up in physical education (PE) lessons in healthy children: (a) to improve the level of motor competence (MC) and (b) to master fundamental motor skills (FMS) patterns, considering the baseline MC level and the time spent when performing different motor tasks. One hundred ninety students (7.43 ± 0.32 years; 52% girls) were included in this randomized controlled trail and grouped up according to MC basal levels (L1-L4). Motor competence and FMS patterns (CAMSA protocol) were assessed before and after the intervention in a group-based INT warm-up (n = 97) and a group-based conventional warm-up (n = 93). The INT program improved MC (p < 0.001; d = 0.71) and FMS (p < 0.001, d = 0.52). The independent predictors of MC change were: baseline MC level (ß = -196; p < 0.012), time spent to perform the task (ß = -0.235 p < 0.003), and participation in the INT program (ß = 0.201; p < 0.005), explaining 71% of its variability. The INT warm-up shows correlations between improvements in MC in relation to time reduction (L1 p = 0.016, d, L2 p = 0.001, and L4 = 0.001) and FMS patterns (L1 p < 0.001, L2 p < 0.003, L3 p < 0.005, and L4 < 0.001) Moreover, only L3, it showed correlation between changes in time and FMS mastery (p = 0.001). Our results showed that a pedagogical approach to an INT program developed as a warm-up in primary school PE lessons can improve MC and FMS patterns in all subjects, independent of the initial MC level. More interestingly, only in L3, the improvement in MC can be explained by the balance in time required to perform the task and the level of improvement in FMS patterns.

Atypical cerebral palsy: genomics analysis enables precision medicine.

PURPOSE: The presentation and etiology of cerebral palsy (CP) are heterogeneous. Diagnostic evaluation can be a prolonged and expensive process that might remain inconclusive. This study aimed to determine the diagnostic yield and impact on management of next-generation sequencing (NGS) in 50 individuals with atypical CP (ACP). METHODS: Patient eligibility criteria included impaired motor function with onset at birth or within the first year of life, and one or more of the following: severe intellectual disability, progressive neurological deterioration, other abnormalities on neurological examination, multiorgan disease, congenital anomalies outside of the central nervous system, an abnormal neurotransmitter profile, family history, brain imaging findings not typical for cerebral palsy. Previous assessment by a neurologist and/or clinical geneticist, including biochemical testing, neuroimaging, and chromosomal microarray, did not yield an etiologic diagnosis. RESULTS: A precise molecular diagnosis was established in 65% of the 50 patients. We also identified candidate disease genes without a current OMIM disease designation. Targeted intervention was enabled in eight families (~15%). CONCLUSION: NGS enabled a molecular diagnosis in ACP cases, ending the diagnostic odyssey, improving genetic counseling and personalized management, all in all enhancing precision medicine practices.

Serum Betaine and Dimethylglycine Are Higher in South Asian Compared with European Pregnant Women in Canada, with Betaine and Total Homocysteine Inversely Associated in Early and Midpregnancy, Independent of Ethnicity.

BACKGROUND: As a methyl donor required in the folate-vitamin B-12 independent remethylation of total homocysteine (tHcy) to methionine, betaine is critical for fetal development. Pregnant South Asian women living in Canada had a higher reported prevalence of low vitamin B-12 status compared with Europeans; betaine concentrations in this population are unknown. OBJECTIVES: We aimed to compare serum betaine concentrations between South Asian and European pregnant women, and to determine the relation between betaine and tHcy concentrations in early pregnancy. METHODS: A retrospective cohort study was conducted using biobanked serum samples of 723 apparently healthy pregnant women of South Asian (50%) and European ethnicity residing in British Columbia, Canada. Betaine, dimethylglycine (DMG), tHcy, and related metabolites were quantified in samples collected in the first (8-13 weeks of gestation) and second (14-20 weeks of gestation) trimesters. The relation between betaine and tHcy concentrations was assessed using a generalized regression model adjusted for weeks of gestation, ethnicity, prepregnancy BMI, maternal age, neonatal sex, parity, total vitamin B-12, folate, pyridoxal 5'-phosphate, and methionine concentrations. RESULTS: Median serum concentrations of betaine and its metabolite DMG were higher in South Asian women in the first (19.8 [IQR: 16.3-25.0] and 1.55 [IQR: 1.30-1.96] $\mu {\rm mol/L} $, respectively) and second trimesters (16.1 [IQR: 12.9-19.8] and 1.42 [IQR: 1.14-1.81] $\mu {\rm mol/L} $, respectively) compared with European women (17.6 [IQR: 13.7-22.6] and 1.38 [IQR: 1.12-1.77] $\mu {\rm mol/L} $, respectively) and (12.9 [IQR: 10.6-16.7] and 1.19 [IQR: 0.97-1.52] $\mu {\rm mol/L} $, respectively; all P values < 0.0001). Betaine was inversely associated with tHcy concentration (ß = -0.0208; 95% CI: -0.0341, -0.00742; P = 0.002). Additionally, total vitamin B-12 was associated with tHcy concentration (ß = -0.0312; 95% CI: -0.0401, -0.0224), after adjusting for confounding factors. CONCLUSIONS: Pregnant South Asian women residing in Canada had higher betaine and DMG concentrations, compared with women of European ethnicity, while betaine and total vitamin B-12 predicted tHcy independent of ethnicity. Our results emphasize the role of betaine, as methyl donor, in the remethylation of tHcy in a folate-replete population.

Reference intervals for serum total vitamin B12 and holotranscobalamin concentrations and their change points with methylmalonic acid concentration to assess vitamin B12 status during early and mid-pregnancy.

Background Maternal vitamin B12 (B-12) adequacy is important for maternal health and optimal fetal growth. However, pregnancy-specific cut-offs for B-12 biomarkers are lacking. Methods Reference intervals for serum total B-12, holotranscobalamin (holoTC) and methylmalonic acid (MMA) concentrations were calculated following CLSI EP28-A3c guidelines in 723 pregnant women of European (50%) and South Asian (50%) ethnicity, residing in British Columbia, Canada, at median (range) 11.4 (8.3-13.9) and 16.1 (14.9-20.9) weeks of gestation. Change point analyses described relationships between log serum MMA concentration with serum total B-12 and holoTC concentrations, assuming linear-linear relationships. Results The central 95% reference interval limits indicated that serum total B-12 <89.9 and <84.0 pmol/L, holoTC <29.5 and <26.0 pmol/L and MMA >371 and >374 nmol/L, in the first and second trimesters, respectively, may indicate B-12 deficiency in pregnant women. The lower limits of total B-12 and holoTC and the upper limits of MMA significantly differed by ethnicity in both trimesters. According to the change point analysis, total B-12 <186 and <180 pmol/L and holoTC <62.2 and <67.5 pmol/L in the first and second trimesters, respectively, suggested an increased probability of impaired intracellular B-12 status, with no difference between ethnicities. Conclusions We present novel reference limits and change points for B-12 biomarkers, which may be employed to identify possible B-12 deficiency in women during early and mid-pregnancy. Future research is needed to validate these cut-offs and determine the predictors and functional outcomes associated with impaired B-12 status in ethnically diverse populations.

Acute Shoshin beriberi syndrome immediately post-kidney transplant with rapid recovery after thiamine administration.

Pediatric kidney transplant surgery is usually well tolerated, despite suboptimal physical conditioning that may result from uremia and nutritional deficiencies that accompany end-stage kidney failure. Nutritional supplementation is used to overcome such deficiencies, especially for children needing dialysis. Thiamine, a water-soluble vitamin also known as vitamin B1, is a critical cofactor in energy metabolism and may be competitively inhibited by the antimetabolite oxythiamine, a uremic toxin that accumulates in kidney failure. We report a case of a thiamine deficiency syndrome leading to overwhelming cardiac dysfunction, metabolic instability, and hemodynamic compromise, after otherwise uneventful kidney transplant surgery. Prior to transplant, this 14-year-old boy was treated with peritoneal dialysis and received thiamine supplementation. Post-transplant, the patient first developed hyperglycemia, then lactic acidosis, and subsequently hemodynamic instability despite escalating treatment with volume resuscitation and inotropic medication. He made a rapid and complete recovery after administration of IV thiamine. This is the first reported case of Shoshin beriberi syndrome in a pediatric kidney transplant recipient. Inadequate dialysis may have been a key factor, with toxin accumulation and thiamine transporter downregulation contributing to his status. Functional thiamine deficiency should be considered as a potential treatable cause of early post-transplant hemodynamic instability.

The p.P479L variant in CPT1A is associated with infectious disease in a BC First Nation.

BACKGROUND: The hepatic carnitine palmitoyltransferase I (CPT1A) p.P479L variant is common in Aboriginal populations across coastal British Columbia, Alaska, the Canadian North, and Greenland. While the high frequency of this variant suggests positive selection, other studies have shown an association with sudden unexpected death in infancy and infection. We utilized administrative health data to evaluate hospitalizations for a single year cohort of children of First Nations descent genotyped for the variant and, matched for location of birth. Seven years of data were reviewed for 150 children split evenly between CPT1A genotypes (homozyous, heterozygous, and noncarrier of the p.P479L variant). RESULTS: Children homozygous for the p.P479L allele had a higher rate of hospital admissions at 2.6 per individual as compared to noncarriers at 0.86. Heterozygous children also showed a significant increase at 1.9 per person. Length of stay per admission was increased for both p.P479L homozygotes and heterozygotes. The odds ratio (OR) for at least one hospitalization for any reason was increased for p.P479L homozygotes relative to noncarriers (OR=10.2, confidence interval [CI] 3.5 to 30.0) as were admissions for dental caries (OR=3.4, CI 1.5 to 7.8), acute lower respiratory tract infections (OR=6.0, CI 1.6 to 22.4), and otitis media (OR=13.5, CI 1.7 to 109.4). CONCLUSIONS: The CPT1A p.P479L variant is associated with an increased rate of hospitalization for those homozygous, primarily for infectious disease causes. Heterozygotes also showed a small but significant increase in hospitalization rates suggesting some dosage effect. Functional studies will be required to identify the underlying pathological mechanism.

Pyruvate Carboxylase Deficiency Type C: A Rare Cause of Acute Transient Flaccid Paralysis with Ketoacidosis.

Pyruvate carboxylase (PC) is a biotin-containing enzyme that is responsible for the adenosine triphosphate-dependent carboxylation of pyruvate to oxaloacetate, a key intermediate in the tricarboxylic acid cycle. PC deficiency (OMIM 266150) is a rare autosomal recessive metabolic disease, causing elevation of pyruvate, lactate, and alanine. Three types of PC deficiency have been described in the literature; A, B, and C. Type A PC deficiency, also called infantile or North American type, is characterized by infantile onset acidosis, failure to thrive, and developmental delay. The second subtype or type B, the neonatal or French form, presents usually in the neonatal period, mostly in the first 72 hours of life with severe lactic acidosis, truncal hypotonia, and seizures. The third type is called type C, is extremely rare with few cases published in the literature. In this case report, we present an 11-month-old girl who presented with acute flaccid paralysis, lethargy, and constipation with elevated ketones and lactate. She was confirmed genetically and biochemically to have PC deficiency type C. The patient's unusual presentation expands the clinical phenotype of this extremely rare disease.

Mitochondrial carbonic anhydrase VA deficiency resulting from CA5A alterations presents with hyperammonemia in early childhood.

Four children in three unrelated families (one consanguineous) presented with lethargy, hyperlactatemia, and hyperammonemia of unexplained origin during the neonatal period and early childhood. We identified and validated three different CA5A alterations, including a homozygous missense mutation (c.697T>C) in two siblings, a homozygous splice site mutation (c.555G>A) leading to skipping of exon 4, and a homozygous 4 kb deletion of exon 6. The deleterious nature of the homozygous mutation c.697T>C (p.Ser233Pro) was demonstrated by reduced enzymatic activity and increased temperature sensitivity. Carbonic anhydrase VA (CA-VA) was absent in liver in the child with the homozygous exon 6 deletion. The metabolite profiles in the affected individuals fit CA-VA deficiency, showing evidence of impaired provision of bicarbonate to the four enzymes that participate in key pathways in intermediary metabolism: carbamoylphosphate synthetase 1 (urea cycle), pyruvate carboxylase (anaplerosis, gluconeogenesis), propionyl-CoA carboxylase, and 3-methylcrotonyl-CoA carboxylase (branched chain amino acids catabolism). In the three children who were administered carglumic acid, hyperammonemia resolved. CA-VA deficiency should therefore be added to urea cycle defects, organic acidurias, and pyruvate carboxylase deficiency as a treatable condition in the differential diagnosis of hyperammonemia in the neonate and young child.

A girl with developmental delay, ataxia, cranial nerve palsies, severe respiratory problems in infancy-Expanding NDST1 syndrome.

NDST1 encodes an enzyme involved in the first steps in the synthesis of heparan sulfate chains, proteoglycans that are regulators found on the cell surface and in the extracellular matrix. Eight individuals homozygous for one of four family-specific missense mutations in the sulfotransferase domain of the enzyme have been described. They have intellectual disability. Some additionally had hypotonia, ataxia. seizures, and/or short stature, but none had history of respiratory problems. No humans with homozygous null mutations are known. ndst1b (orthologous to NDST1) morpholino knockdown in zebrafish (Danio rerio) causes delayed development, craniofacial cartilage abnormalities, shortened body and pectoral fin length. Ndst1 homozygous null mice have craniofacial abnormalities and die within the first 10 h of life of respiratory failure. We report a girl upon whom deep phenotyping, extensive genetic and biochemical investigations, and exome sequencing were performed. She had cranial nerves dysfunction, gastroesophageal reflux, history of a seizure, ataxia, developmental delays, head sparing failure to thrive, and minor malformations including distinctive facial features and a bifid uvula. Compound heterozygous mutations in NDST1 were identified, in the heparan sulfate N deacetylatase domain of one allele and the sulfotransferase domain of the other allele. This report expands the phenotypic spectrum of Ndst1 deficiency in humans. © 2017 Wiley Periodicals, Inc.

Pregnant women of South Asian ethnicity in Canada have substantially lower vitamin B12 status compared with pregnant women of European ethnicity.

Maternal vitamin B12 (B12) status has been inversely associated with adverse pregnancy outcomes and positively with fetal growth and infant development. South Asians, Canada's largest ethnic minority, are prone to B12 deficiency. Yet, data are lacking on B12 status in South Asian pregnant women in North America. We sought to determine B12 status, using multiple biomarkers, in 1st and 2nd trimester pregnant women of South Asian and, for comparison, European ethnicity living in Vancouver, Canada. In this retrospective cohort study, total B12, holotranscobalamin (holoTC), methylmalonic acid (MMA), and total homocysteine concentrations were quantified in two routinely collected (mean gestational week: 11·5 (range 8·3-13·9) and 16·5 (range 14·9-20·9)), banked serum samples of 748 healthy pregnant South Asian (n 371) and European (n 377) women. South Asian pregnant women had significantly lower B12 status than European pregnant women at both time points, as indicated by lower serum total B12 and holoTC concentrations, and higher MMA concentrations (all P≤0·001). The largest difference, which was substantial (Cohen's d≥0·5), was observed in mean serum total B12 concentrations (1st trimester: 189 (95 % CI 180, 199) v. 246 (95 % CI 236, 257) pmol/l; 2nd trimester: 176 (95 % CI 168, 185) v. 226 (95 % CI 216, 236) pmol/l). Further, South Asian ethnicity was a significant negative predictor of B12 status during pregnancy. South Asian women living in Vancouver have substantially lower B12 status during early pregnancy. Future research identifying predictors and health consequences of this observed difference is needed to allow for targeted interventions.

A three-tier algorithm for guanidinoacetate methyltransferase (GAMT) deficiency newborn screening.

BACKGROUND: Guanidinoacetate methyltransferase (GAMT) deficiency is a rare disorder of creatine biosynthesis presenting with epilepsy and developmental delay in infancy. Excellent developmental outcomes have been reported for infants treated from birth due to a family history. The BC Newborn Screening Program initiated a 3year pilot screening study for GAMT deficiency to evaluate the performance of a novel three-tiered screening approach. METHODS: Over 36months all bloodspots submitted for routine newborn screening were included in the pilot study (de-identified). Initial GAA measurement was integrated into the standard acylcarnitine/amino acid first-tier assay. All samples with elevated GAA were subjected to second-tier GAA analysis by LC-MS/MS integrated into an existing branched-chain amino acid (MSUD) method. GAMT gene sequencing was completed on the original bloodspot for all specimens with elevated GAA on the second-tier test. The protocol allowed for re-identification for treatment of any specimen with one or two likely pathogenic GAMT mutations. RESULTS: Over the study period 135,372 specimens were tested with 259 (0.19%) over the first-tier GAA cut-off. The second-tier assay removed an interference falsely elevating GAA levels, and only 3 samples required genotyping. No mutations were identified in any samples, all were deemed negative screens and no follow-up was initiated. CONCLUSIONS: A three-tier algorithm for GAMT newborn screening showed excellent test performance with zero false positives. No cases were detected, supporting a low incidence for this disorder. Given the low incremental costs and evidence of positive outcomes with early intervention, GAMT deficiency remains an excellent candidate for newborn screening.

Health economic evaluation of plasma oxysterol screening in the diagnosis of Niemann-Pick Type C disease among intellectually disabled using discrete event simulation.

BACKGROUND: Recently a less invasive method of screening and diagnosing Niemann-Pick C (NP-C) disease has emerged. This approach involves the use of a metabolic screening test (oxysterol assay) instead of the current practice of clinical assessment of patients suspected of NP-C (review of medical history, family history and clinical examination for the signs and symptoms). Our objective is to compare costs and outcomes of plasma oxysterol screening versus current practice in diagnosis of NP-C disease among intellectually disabled (ID) patients using decision-analytic methods. METHODS: A discrete event simulation model was conducted to follow ID patients through the diagnosis and treatment of NP-C, forecast the costs and effectiveness for a cohort of ID patients and compare the outcomes and costs in two different arms of the model: plasma oxysterol screening and routine diagnosis procedure (anno 2013) over 5 years of follow up. Data from published sources and clinical trials were used in simulation model. Unit costs and quality-adjusted life-years (QALYs) were discounted at a 3% annual rate in the base case analysis. Deterministic and probabilistic sensitivity analyses were conducted. RESULTS: The outcomes of the base case model showed that using plasma oxysterol screening for diagnosis of NP-C disease among ID patients is a dominant strategy. It would result in lower total cost and would slightly improve patients' quality of life. The average amount of cost saving was $3642 CAD and the incremental QALYs per each individual ID patient in oxysterol screening arm versus current practice of diagnosis NP-C was 0.0022 QALYs. Results of sensitivity analysis demonstrated robustness of the outcomes over the wide range of changes in model inputs. CONCLUSION: Whilst acknowledging the limitations of this study, we conclude that screening ID children and adolescents with oxysterol tests compared to current practice for the diagnosis of NP-C is a dominant strategy with clinical and economic benefits. The less costly, more sensitive and specific oxysterol test has potential to save costs to the healthcare system while improving patients' quality of life and may be considered as a routine tool in the NP-C diagnosis armamentarium for ID. Further research is needed to elucidate its effectiveness in patients presenting characteristics other than ID in childhood and adolescence.

Performance of serum and dried blood spot acylcarnitine profiles for detection of fatty acid ß-oxidation disorders in adult patients with rhabdomyolysis.

BACKGROUND: Plasma/serum and dried blood spot (DBS) acylcarnitine profiles (ACPs) are key to the diagnosis of mitochondrial fatty acid ß-oxidation disorders (FAODs). Despite their significant clinical applications, limited published data exists to compare their sensitivities and specificities. We retrospectively evaluated these two methods in adult patients with a history of rhabdomyolysis; investigated for an underlying FAOD. METHODS: A retrospective study was completed for adult patients (investigated between 2003 and 2011) meeting the inclusion criteria of a history of recurrent rhabdomyolysis or one episode of rhabdomyolysis with a history of exercise intolerance. All subjects underwent investigations for an underlying FAOD including DBS and serum ACP analysis concurrently collected during a symptom-free period, and skin biopsy for cultured fibroblast fatty acid oxidation studies or enzyme activity measurement, as indicated, with or without molecular confirmation. Their medical records were reviewed, and the performance of the two methods were compared. RESULTS: Seven out of 31 subjects (22.6 %) were diagnosed with an underlying FAOD. Long chain acylcarnitines were more markedly elevated in serum samples from confirmed CPTII cases (n = 4) as compared to matched DBS profiles. The sensitivity and specificity of DBS ACP was 71.4 % (95 % CI, 0.30-0.95) and 100 % (95 % CI, 0.79-1.00), respectively, compared to a sensitivity of 100 % (95 % CI, 0.56-1.00) and a specificity of 94.7 % (95 % CI, 0.72-1.00) for serum ACP. CONCLUSION: FAODs appear to be a common cause of recurrent rhabdomyolysis or rhabdomyolysis with a history of exercise induced myalgia. At least historically, FAODs maybe underdiagnosed in adults with rhabdomyolysis. This study suggests that serum ACP might be more sensitive than DBS ACP for detection of an underlying FAOD in adults with rhabdomyolysis while asymptomatic.

Detection of a novel intragenic rearrangement in the creatine transporter gene by next generation sequencing.

Deficiency caused by mutations in the creatine transporter gene (SLC6A8/CT1) is an X-linked form of intellectual disability. The presence of highly homologous pseudogenes and high GC content of SLC6A8 genomic sequence complicates the molecular diagnosis of this disorder. To minimize the pseudogene interference, exons 2 to 13 of SLC6A8 were amplified as a single PCR product using gene-specific long-range PCR (LR-PCR) primers. The GC-rich exon 1 and its flanking intronic sequences were amplified separately in a short fragment under GC-rich conditions and a touchdown PCR program. Traditional Sanger sequence analysis of all coding exons of SLC6A8 from a 3-year-old boy with creatine transporter deficiency did not detect deleterious mutations. The long-range PCR product was used as template followed by massively parallel sequencing (MPS) on HiSeq2000. We were able to detect a tandem duplication involving part of exons 11 and 12 in the SLC6A8 gene. The deduced c.1592_1639dup133 mutation was confirmed to be a hemizygous insertion by targeted genomic DNA and cDNA Sanger sequencing. Combination of deep sequencing technology with long-range PCR revealed a novel intragenic duplication in the SLC6A8 gene, providing a definitive molecular diagnosis of creatine transporter deficiency in a male patient.

Validity and Reliability of the V-Cut Dribbling Test in Young Basketball Players.

PURPOSE: Change of direction while dribbling appears to be of interest for on-court performance in basketball. The study aim was to assess the validity and reliability of the V-cut dribbling test (VcutBk) in young basketball players. METHODS: Ninety-two young basketball players from 8 to 21 years old (74% male) were classified in relation to peak height velocity (PHV) offset. To examine validity and test-retest reliability, VcutBk was performed in 2 identical sessions separated by 1 week. Participants also performed the V-cut test and linear sprint test with and without dribbling to analyze correlations between tests in different somatic maturity stages. RESULTS: The relationships of the VcutBk with the other tests and skill-time-related deficits were interpreted from large (r > .51) to very large (r > .71). The comparisons between pre-PHV and post-PHV groups of basketball players showed significant and large effect in the VcutBk (d = 2.04; mean difference = 2.59; 95% CI, 1.86 to 3.32). Also, significant main effects when comparing PHV groups were reported in all skill-time-related deficits (P < .001, ηp2=.13-.28, moderate to large effect size). Test-retest reliability and signal-to-noise ratio analysis did not show substantial between-trials differences in VcutBk. Reliability scores showed high intraclass correlation coefficient (.95) and low coefficient of variation (0.23%). CONCLUSIONS: The VcutBk seems to be a valid and reliable test to assess change of direction while dribbling. VcutBk performance and skill-time-related deficits seem to be sensitive to somatic maturity. Basketball coaches should consider the VcutBk to assess young basketball players.