Second-tier Testing for 21-Hydroxylase Deficiency in the Netherlands: A Newborn Screening Pilot Study

CONTEXT

Newborn screening (NBS) for classic congenital adrenal hyperplasia (CAH) consists of 17-hydroxyprogesterone (17-OHP) measurement with gestational age-adjusted cutoffs. A second heel puncture (HP) is performed in newborns with inconclusive results to reduce false positives.

OBJECTIVE

We assessed the accuracy and turnaround time of the current CAH NBS algorithm in comparison with alternative algorithms by performing a second-tier 21-deoxycortisol (21-DF) pilot study.

METHODS

Dried blood spots (DBS) of newborns with inconclusive and positive 17-OHP (immunoassay) first HP results were sent from regional NBS laboratories to the Amsterdam UMC Endocrine Laboratory. In 2017-2019, 21-DF concentrations were analyzed by LC-MS/MS in parallel with routine NBS. Diagnoses were confirmed by mutation analysis.

RESULTS

A total of 328 DBS were analyzed; 37 newborns had confirmed classic CAH, 33 were false-positive and 258 were categorized as negative in the second HP following the current algorithm. With second-tier testing, all 37 confirmed CAH had elevated 21-DF, while all 33 false positives and 253/258 second-HP negatives had undetectable 21-DF. The elevated 21-DF of the other 5 newborns may be NBS false negatives or second-tier false positives. Adding the second-tier results to inconclusive first HPs reduced the number of false positives to 11 and prevented all 286 second HPs. Adding the second tier to both positive and inconclusive first HPs eliminated all false positives but delayed referral for 31 CAH patients (1-4 days).

CONCLUSION

Application of the second-tier 21-DF measurement to inconclusive first HPs improved our CAH NBS by reducing false positives, abolishing the second HP, and thereby shortening referral time.

The APOE ε4 allele in relation to pre- and postsurgical cognitive functioning of patients with primary brain tumors

BACKGROUND

Recent studies suggest a relationship between the APOE ε4 allele and cognitive outcome in patients treated for malignant brain tumors. Still, longitudinal investigations that include a pretreatment cognitive assessment are lacking and APOE's effects in patients with benign tumors are understudied. This study investigated presurgical cognitive performance and postsurgical change in ε4-carrying and non-carrying patients with glioma and meningioma.

METHODS

Neuropsychological test scores (CNS Vital Signs battery [seven measures], Digit Span Forward/Backward, Letter Fluency test) were obtained as part of a prospective study in which patients with meningioma and glioma underwent cognitive assessment 1 day before (T0, n = 505) and 3 (T3, n = 418) and 12 months after (T12, n = 167) surgery. APOE isoforms were identified retrospectively. ε4 carriers and non-carriers were compared with regard to pretreatment cognitive performance on the group and individual level. Changes in performances over time were compared with longitudinal mixed model analysis in the total sample and the subgroup receiving adjuvant treatment.

RESULTS

Carriers and non-carriers did not differ with regard to pretreatment performance. No significant main effect of ε4 carrier status or interaction between time (T0-T12) and carrier status was found on any of the tests in the whole sample nor in the sample receiving adjuvant treatment.

CONCLUSIONS

This study found no evidence of increased vulnerability for pretreatment cognitive dysfunction or cognitive decline within 1 year after surgery in APOE ε4-carrying meningioma and glioma patients. Investigations that include larger samples at longer-term follow-up are recommended to investigate potential late treatment effects.

Evaluation of 11 years of newborn screening for maple syrup urine disease in the Netherlands and a systematic review of the literature: Strategies for optimization

Maple syrup urine disease (MSUD) leads to severe neurological deterioration unless diagnosed early and treated immediately. We have evaluated the effectiveness of 11 years of MSUD newborn screening (NBS) in the Netherlands (screening >72 hours, referral if both total leucine (Xle) and valine ≥400 μmol/L blood) and have explored possibilities for improvement by combining our data with a systematic literature review and data from Collaborative Laboratory Integrated Reports (CLIR). Dutch MSUD NBS characteristics and accuracy were determined. The hypothetical referral numbers in the Dutch population of additional screening markers suggested by CLIR were calculated. In a systematic review, articles reporting NBS leucine concentrations of confirmed patients were included. Our data showed that NBS of 1 963 465 newborns identified 4 MSUD patients and led to 118 false-positive referrals (PPV 3.28%; incidence 1:491 000 newborns). In literature, leucine is the preferred NBS parameter. Total leucine (Xle) concentrations (mass-spectrometry) of 53 detected and 8 false-negative patients (sampling age within 25 hours in 3 patients) reported in literature ranged from 288 to 3376 (median 900) and 42 to 325 (median 209) μmol/L blood respectively. CLIR showed increasing Xle concentrations with sampling age and early NBS sampling and milder variant MSUD phenotypes with (nearly) normal biochemical profiles are causes of false-negative NBS results. We evaluated the effect of additional screening markers and established the Xle/phenylalanine ratio as a promising additional marker ratio for increasing the PPV, while maintaining high sensitivity in the Dutch MSUD NBS.

Simultaneous Determination of Underivatized Vitamin B1 and B6 in Whole Blood by Reversed Phase Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry

Background

Vitamin B1 (thiamine-diphosphate) and B6 (pyridoxal-5’phosphate) are micronutrients. Analysis of these micronutrients is important to diagnose potential deficiency which often occurs in elderly people due to malnutrition, in severe alcoholism and in gastrointestinal compromise due to bypass surgery or disease. Existing High Performance Liquid Chromatography (HPLC) based methods include the need for derivatization and long analysis time. We developed an Ultra High Performance Liquid Chromatography Tandem Mass spectrometry (UHPLC-MS/MS) assay with internal standards for simultaneous measurement of underivatized thiamine-diphosphate and pyridoxal-5’phosphate without use of ion pairing reagent.

Methods

Whole blood, deproteinized with perchloric acid, containing deuterium labelled internal standards thiamine-diphosphate(thiazole-methyl-D₃) and pyridoxal-5’phosphate(methyl-D₃), was analyzed by UHPLC-MS/MS. The method was validated for imprecision, linearity, recovery and limit of quantification. Alternate (quantitative) method comparisons of the new versus currently used routine HPLC methods were established with Deming regression.

Results

Thiamine-diphosphate and pyridoxal-5’phosphate were measured within 2.5 minutes instrumental run time. Limits of detection were 2.8 nmol/L and 7.8 nmol/L for thiamine-diphosphate and pyridoxal-5’phosphate respectively. Limit of quantification was 9.4 nmol/L for thiamine-diphosphate and 25.9 nmol/L for pyridoxal-5’phosphate. The total imprecision ranged from 3.5–7.7% for thiamine-diphosphate (44–157 nmol/L) and 6.0–10.4% for pyridoxal-5’phosphate (30–130 nmol/L). Extraction recoveries were 101–102% ± 2.5% (thiamine-diphosphate) and 98–100% ± 5% (pyridoxal-5’phosphate). Deming regression yielded slopes of 0.926 and 0.990 in patient samples (n = 282) and national proficiency testing samples (n = 12) respectively, intercepts of +3.5 and +3 for thiamine-diphosphate (n = 282 and n = 12) and slopes of 1.04 and 0.84, intercepts of -2.9 and +20 for pyridoxal-5’phosphate (n = 376 and n = 12).

Conclusion

The described UHPLC-MS/MS method allows simultaneous determination of underivatized thiamine-diphosphate and pyridoxal-5’phosphate in whole blood without intensive sample preparation.

Erfolgreiche Behandlung der klinischen Manifestationen des Muckle-Wells-Syndroms mit Anakinra

HISTORY

A 58-year-old woman and her 18-year-old daughter were first seen in our rheumatology centre after having experienced many years of periodic fever, arthralgia and urticaria. Some months ago a diagnosis of Muckle-Wells syndrome (MWS) had been made and confirmed by genetic testing. The mother had developed partial deafness and substantial loss of vision. Her daughter had been suffering mainly from urticaria and fever at least once daily.

THERAPY

Because of the established role of interleukin (IL)-1 in this hereditary disease and some positive case reports, we decided to treat these patients with the IL-1 receptor antagonist anakinra. The patients reported a great success of this treatment with virtually complete absence of any acute MWS-associated symptoms.

CONCLUSION

Therapy of MWS with anakinra seems to be highly efficacious for several clinical manifestations of this disease, including laboratory markers for inflammation. It is possible that organ destruction may be prevented by this medication.

Chromosomal integration of tcb chlorocatechol degradation pathway genes as a means of expanding the growth substrate range of bacteria to include haloaromatics

The tcbR-tcbCDEF gene cluster, coding for the chlorocatechol ortho-cleavage pathway in Pseudomonas sp. strain P51, has been cloned into a Tn5-based minitransposon. The minitransposon carrying the tcb gene cluster and a kanamycin resistance gene was transferred to Pseudomonas putida KT2442, and chromosomal integration was monitored by selection either for growth on 3-chlorobenzoate or for kanamycin resistance. Transconjugants able to utilize 3-chlorobenzoate as a sole carbon source were obtained, although at a >100-fold lower frequency than kanamycin-resistant transconjugants. The vast majority of kanamycin-resistant transconjugants were not capable of growth on 3-chlorobenzoate. Southern blot analysis revealed that many transconjugants selected directly on 3-chlorobenzoate contained multiple chromosomal copies of the tcb gene cluster, whereas those selected for kanamycin resistance possessed a single copy. Subsequent selection of kanamycin resistance-selected single-copy transconjugants for growth on 3-chlorobenzoate yielded colonies capable of utilizing this carbon source, but no amplification of the tcb gene cluster was apparent. Introduction of two copies of the tcb gene cluster without prior 3-chlorobenzoate selection resulted in transconjugants able to grow on this carbon source. Expression of the tcb chlorocatechol catabolic operon in P. putida thus represents a useful model system for analysis of the relationship among gene dosage, enzyme expression level, and growth on chloroaromatic substrates.

Membrane decoration by amphiphilic block copolymers in bicontinuous microemulsions

The effect of various amphiphilic block copolymers of different molar masses on the structure and phase behavior of ternary amphiphilic systems (water, oil, and nonionic surfactant) is investigated. Small amounts of PEP-PEO block copolymer lead to a dramatic increase in the volumes of oil and water, which can be solubilized in a bicontinuous microemulsion. High-precision neutron scattering experiments with a sophisticated contrast variation technique demonstrate that the polymers form uniformly distributed mushroom conformations on the surfactant membrane. Based on these observations, we propose a universal mechanism for the swelling behavior, which is due to the variation of the membrane curvature elasticity.

Cotranscription of a GTPase gene from the cyanobacterium Synechocystis PCC 6803 and a P-type Ca(2+)-ATPase gene

A GTPase gene adjacent to the Ca(2+)-ATPase gene from Synechocystis PCC 6803 has been sequenced. It encodes for a protein of 456 amino acids revealing high homology to so-called 50K proteins of Bacillus subtilis and Pseudomonas putida. Cotranscription of GTPase and Ca(2+)-ATPase genes has been shown by reverse transcription PCR.