Duchenne Muscular Dystrophy Newborn Screening: Evaluation of a New GSP® Neonatal Creatine Kinase-MM Kit in a US and Danish Population

Value of serum muscular creatinine phosphokinase levels in patients with adenomyosis as a non-invasive diagnostic marker

OBJECTIVE

In the present study, we aimed to compare serum CK-MM levels in patients with and without adenomyosis and to investigate whether CK-MM level can be a non-invasive marker for myometrial damage due to adenomyosis.

MATERIALS AND METHODS

Our study was a prospective case-control study in a tertiary center and consisted of 40 patients with a clinical/ultrasonographic diagnosis of adenomyosis and 40 patients without a clinical/ultrasonographic diagnosis of adenomyosis as the control group based on recently published morphological uterus sonographic assessment (MUSA) criteria. Individuals of similar age who signed a voluntary consent form were included in our study. Demographic, clinical, and laboratory findings of the patients in both groups were recorded. Blood serum samples were used for the determination of serum CK-MM levels of the participants in our study. The samples were analyzed by using the human CK-MM enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

In our study, the mean serum CK-MM level was 16.2 ± 21.7 (ng/dL) in patients with adenomyosis and 2.6 ± 2.2 (ng/dL) in patients without adenomyosis. Serum CK-MM level was statistically significantly higher in the patient group with adenomyosis than in the control group (p < 0.001). The CK-MM threshold value of 3.43 ng/mL, with a sensitivity of 82.5% and specificity of 85%, has been found to be a valuable distinguishing level in patients with and without adenomyosis.

CONCLUSION

In this study, we demonstrated that serum CK-MM can be used as a non-invasive diagnostic method in patients with adenomyosis. As the number of studies around this subject in the literature is insufficient, larger studies are needed to use CK-MM as a diagnostic marker in adenomyosis.

Creatine Kinase-MM/Proto-oncogene Tyrosine-Protein Kinase Receptor as a Sensitive Indicator for Duchenne Muscular Dystrophy Carriers

Duchenne muscular dystrophy (DMD), a lethal X-linked recessive genetic disease, is characterized by progressive muscle wasting which will lead to premature death by cardiorespiratory complications in their late twenties. And 2.5-19% DMD carriers that also suffer from skeletal muscle damage or dilated cardiomyopathy when diagnosed as soon as possible is meaningful for prenatal diagnosis and advance warning for self-health. The current DMD carrier screening mainly relies on detecting serum creatine kinase activity, covering only 50-70% DMD carriers which will cause many false negatives and require the discovery of highly effective biomarker and simple detection procedure for DMD carriers. In this article, we have compiled a comprehensive summary of all documented biomarkers associated with DMD and categorized them based on their expression patterns. We specifically pinpointed novel DMD biomarkers, previously unreported in DMD carriers, and conducted further investigations to explore their potential. Compared to creatine kinase activity alone in DMD carriers, creatine kinase-MM can improve the specificity from 73 to 81%. And our investigation revealed another promising protein: proto-oncogene tyrosine-protein kinase receptor (RET). When combined with creatine kinase-MM (creatine kinase-MM/RET ratio), it significantly enhances the specificity (from 81 to 83%) and sensitivity (from 71.4 to 93%) of detecting DMD carriers in serum. Moreover, we successfully devised an efficient method for extracting RET from dried blood spots. This breakthrough allowed us to detect both creatine kinase-MM and RET using dried blood spots without compromising the detection rate.

Age-Related Blood Levels of Creatine Kinase-MM in Newborns and Patients with Duchenne Muscular Dystrophy: Considerations for the Development of Newborn Screening Algorithms

Duchenne muscular dystrophy (DMD) is an X-linked progressive disorder and the most common type of muscular dystrophy in children. As newborn screening (NBS) for DMD undergoes evaluation for the Recommended Uniform Screening Panel and is already mandated in multiple states, refining NBS algorithms is of utmost importance. NBS for DMD involves measuring creatine kinase-MM (CK-MM) concentration-a biomarker of muscle damage-in dried blood spots. The current test is FDA-approved for samples obtained less than 72 h after birth. Separate reference ranges are needed for samples collected later than 72 h after birth. In this study, we investigated the relationship between age and CK-MM in presumed healthy newborns to inform NBS algorithm designs. In patients with DMD, CK-MM is persistently elevated in childhood and adolescence, while it may be transiently elevated for other reasons in healthy newborns. CK-MM decrease over time was demonstrated by a population sample of 20,306 presumed healthy newborns tested between 0 and 60 days of life and repeat testing of 53 newborns on two separate days. In the population sample, CK-MM concentration was highest in the second 12 h period of life (median = 318 ng/mL) when only 57.6% of newborns tested below 360 ng/mL, the lowest previously published cutoff. By 72 h of age, median CK-MM concentration was 97 ng/mL, and 96.0% of infants had concentrations below 360 ng/mL. Between 72 h and 60 days, median CK-MM concentration ranged from 32 to 37 ng/mL. Establishing age-related cutoffs is crucial for optimizing the sensitivity and specificity of NBS for DMD.

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

Diagnostic Accuracy of Creatine Kinase Isoenzyme-MM Test in Newborn Screening for Duchenne Muscular Dystrophy: A Systematic Review and Meta-Analysis

BACKGROUND

To systematically evaluate the diagnostic accuracy of the creatine kinase isoenzyme-MM (CK-MM) test in newborn screening for Duchenne muscular dystrophy (DMD).

METHODS

A comprehensive literature search was conducted up to October 31, 2022, in PubMed, Embase, Cochrane Library, Web of Science, and Scopus Database. To evaluate the diagnostic value, the sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), area under the curve (AUC), and Q∗ index were pooled. Threshold effect followed by subgroup analysis and meta-regression were performed to explore the source of heterogeneity. Sensitivity analysis was used to verify the robustness of the findings.

RESULTS

A total seven studies with 248,853 newborns was included in our meta-analysis. The pooled SEN and SPE were 1.00 (95% confidence interval [CI]: 0.89∼1.00) and 1.00 (95% CI: 1.00 to 1.00), respectively; the PLR and NLR were 1004.59 (95% CI: 251.37∼4014.91) and 0.13 (95% CI: 0.05∼0.34), respectively; the DOR was 877.96 (95% CI: 983.24∼78,366.32); the AUC and Q index were 0.8683 and 0.9326, respectively. Sensitivity analysis showed that two studies had an impact on the pooled results and mainly contributed to the heterogeneity.

CONCLUSIONS

CK-MM test demonstrated high accuracy in newborn screening for DMD and may be a valuable alternative in the early diagnosis of the disease followed by confirmatory genetic testing.

[Screening for Duchenne muscular dystrophy in newborns in the Ningxia region]

OBJECTIVES

To evaluate the incidence rate of Duchenne muscular dystrophy (DMD) in the male newborns in the Ningxia region and establish a critical threshold for screening DMD in newborns to distinguish between the normal population and affected individuals.

METHODS

A total of 10 000 male newborns were screened using immunofluorescence analysis of creatine kinase isoenzyme concentrations in heel spot dried blood specimens. Newborns with the concentrations higher than the critical threshold were recalled for serum creatine kinase measurements. Genetic testing was performed to confirm diagnosis in cases showing abnormalities.

RESULTS

Among the screened 10 000 male newborns, two were confirmed to have DMD through genetic testing, resulting in a preliminary estimated incidence rate of 1/5 000 for male newborns in the Ningxia region. The critical threshold for creatine kinase isoenzyme concentration in newborns in this region was determined to be 468.57 ng/mL.

CONCLUSIONS

Screening for DMD in newborns is feasible in the Ningxia region. Early screening, diagnosis, and treatment of DMD can improve the quality of life for affected individuals and help families make informed decisions regarding further pregnancies.

Two years of newborn screening for Duchenne muscular dystrophy as a part of the statewide Early Check research program in North Carolina

PURPOSE

Current and emerging treatments for Duchenne muscular dystrophy (DMD) position DMD as a candidate condition for newborn screening (NBS). In anticipation of the nomination of DMD for universal NBS, we conducted a prospective study under the Early Check voluntary NBS research program in North Carolina, United States.

METHODS

We performed screening for creatine kinase-MM (CK-MM), a biomarker of muscle damage, on residual routine newborn dried blood spots (DBS) from participating newborns. Total creatine kinase testing and next generation sequencing of an 86-neuromuscular gene panel that included DMD were offered to parents of newborns who screened positive. Bivariate and multivariable analyses were performed to assess effects of biological and demographic predictors on CK-MM levels in DBS.

RESULTS

We screened 13,354 newborns and identified 2 males with DMD. The provisional 1626 ng/mL cutoff was raised to 2032 ng/mL to improve specificity, and additional cutoffs (900 and 360 ng/mL) were implemented to improve sensitivity for older and low-birthweight newborns.

CONCLUSION

Population-scale screening for elevated CK-MM in DBS is a feasible approach to identify newborns with DMD. Inclusion of birthweight- and age-specific cutoffs, repeat creatine kinase testing after 72 hours of age, and DMD sequencing improve sensitivity and specificity of screening.

A qualitative study to understand the Duchenne muscular dystrophy experience from the parent/patient perspective

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare, severe, fatal neuromuscular disease characterized by progressive atrophy and muscle weakness, resulting in loss of ambulation, decreased upper body function, and impaired cardiorespiratory function. This study aimed to generate qualitative evidence to describe the primary symptoms and impacts of DMD in ambulatory and non-ambulatory patients as reported by patient/caregiver dyads. Information was also gathered on expectations for future DMD treatments.

METHODS

Forty-six dyads (caregiver and patients with DMD aged 4 to 22 years) participated in 60-min semi-structured video interviews. Interview transcripts were analyzed using thematic analysis. Differences in experiences with DMD by ambulation status were examined.

RESULTS

Mean ages of ambulatory (n = 28) and non-ambulatory participants (n = 18) were 8.7 and 11.3 years, respectively, with an average age of diagnosis of 3.7 years (SD = 2.3). The primary symptoms reported by both groups were lack of strength (ambulatory: n = 28, 100.0%; non-ambulatory: n = 17, 94.4%) and fatigue (ambulatory: n = 24, 85.7%; non-ambulatory: n = 14, 77.8%). Physical function was the domain that was most impacted by DMD, with participants describing progressive decline of physical function due to loss of physical strength as the primary defining feature of the disease across all stages of ambulatory ability. For those who maintained ambulatory ability at the time of the interview, physical function impacts described impaired mobility (e.g., climbing stairs: n = 16, 57.1%; running: n = 13, 46.4%), impaired upper body function, in particular fine motor skills like holding a pen/pencil or buttoning clothes (n = 17, 60.7%), problem with transfers (e.g., getting off the floor: n = 10, 35.7%), and activities of daily living (ADLs; n = 15, 53.6%). For non-ambulatory participants, the functional impacts most frequently described were problems with transfers (e.g., getting in/out of bed: n = 13, 72.2%; getting in/out of chair or position in bed: both n = 10, 55.6%), impaired upper body function (reaching: n = 14, 77.8%), and ADLs (n = 15, 83.3%). Meaningful treatment goals differed by ambulatory status; for ambulatory participants, goals included maintaining current functioning (n = 20, 71.4%), improving muscle strength (n = 7, 25.9%), and reducing fatigue (n = 6, 22.2%). For non-ambulatory participants, these included increased upper body strength (n = 8, 42.1%) and greater independence in ADLs (n = 6, 31.6%). A preliminary conceptual model was developed to illustrate the primary symptoms and physical function impacts of DMD and capture their relationship to disease progression.

CONCLUSION

This study contributes to the limited qualitative literature by characterizing impacts of physical limitations and symptoms of DMD on disease progression and thus providing insights into the lived experience with DMD. Differences in treatment goals were also identified based on ambulatory status. Taken together, these findings can help inform patient-centered measurement strategies for evaluating outcomes in DMD clinical research.

Newborn screening for Duchenne muscular dystrophy: A two-year pilot study

OBJECTIVE

Duchenne muscular dystrophy (DMD) is an X-linked disorder resulting in progressive muscle weakness and atrophy, cardiomyopathy, and in late stages, cardiorespiratory impairment, and death. As treatments for DMD have expanded, a DMD newborn screening (NBS) pilot study was conducted in New York State to evaluate the feasibility and benefit of NBS for DMD and to provide an early pre-symptomatic diagnosis.

METHODS

At participating hospitals, newborns were recruited to the pilot study, and consent was obtained to screen the newborn for DMD. The first-tier screen measured creatine kinase-MM (CK-MM) in dried blood spot specimens submitted for routine NBS. Newborns with elevated CK-MM were referred for genetic counseling and genetic testing. The latter included deletion/duplication analysis and next-generation sequencing (NGS) of the DMD gene followed by NGS for a panel of neuromuscular conditions if no pathogenic variants were detected in the DMD gene.

RESULTS

In the two-year pilot study, 36,781 newborns were screened with CK-MM. Forty-two newborns (25 male and 17 female) were screen positive and referred for genetic testing. Deletions or duplications in the DMD gene were detected in four male infants consistent with DMD or Becker muscular dystrophy. One female DMD carrier was identified.

INTERPRETATION

This study demonstrated that the state NBS program infrastructure and screening technologies we used are feasible to perform NBS for DMD. With an increasing number of treatment options, the clinical utility of early identification for affected newborns and their families lends support for NBS for this severe disease.

Factors Influencing Creatine Kinase-MM Concentrations in Newborns and Implications for Newborn Screening for Duchenne Muscular Dystrophy

INTRODUCTION

Newborn screening for Duchenne muscular dystrophy can be performed via a first-tier creatine kinase-MM measurement followed by reflex testing to second-tier molecular analysis of the DMD gene. In order to establish appropriate cut-offs for the creatine kinase-MM screen, factors that influence creatine kinase-MM in newborns were investigated.

MATERIALS AND METHODS

Creatine kinase-MM data from a consented pilot study in New York State were collected over a two-year period and combined with de-identified validation data and analyzed. Univariate analysis and multiple linear regression analysis were performed.

RESULTS

The analysis indicated that age of newborn at specimen collection, gestational age and birth weight were significant influencers of CK-MM levels in newborns. In addition, to a lesser extent, sex, race/ethnicity and seasonal temperature also affect CK-MM levels in newborns.

CONCLUSIONS

To reduce false positive and false negative cases, newborn screening programs should be cognizant of factors that influence CK-MM when determining cut-offs for the assay. Variability based on age at specimen collection and birth weight are primarily observed within the first week of life. Therefore, particularly during this time period, multi-tiered cut-offs based on age of collection and lower cut-offs for premature and low birth weight babies are recommended. Other cut-off determinants may include sex, race/ethnicity and seasonal temperature.

Assessing the value of delandistrogene moxeparvovec (SRP-9001) gene therapy in patients with Duchenne muscular dystrophy in the United States

Background: Delandistrogene moxeparvovec (SRP-9001) is an investigational gene therapy that may delay progression of Duchenne muscular dystrophy (DMD), a severe, rare neuromuscular disease caused by DMD gene mutations. Early cost-effectiveness analyses are important to help contextualize the value of gene therapies for reimbursement decision making. Objective: To determine the potential value of delandistrogene moxeparvovec using a cost-effectiveness analysis. Study design: A simulation calculated lifetime costs and equal value of life years gained (evLYG). Inputs included extrapolated clinical trial results and published utilities/costs. As a market price for delandistrogene moxeparvovec has not been established, threshold analyses established maximum treatment costs as they align with value, including varying willingness-to-pay up to $500,000, accounting for severity/rarity. Setting: USA, healthcare system perspective Patients: Boys with DMD Intervention: Delandistrogene moxeparvovec plus standard of care (SoC; corticosteroids) versus SoC alone Main outcome measure: Maximum treatment costs at a given willingness-to-pay threshold Results: Delandistrogene moxeparvovec added 10.30 discounted (26.40 undiscounted) evLYs. The maximum treatment cost was approximately $5 M, assuming $500,000/evLYG. Varying the benefit discount rate to account for the single administration increased the estimated value to #$5M, assuming $500,000/evLYG. Conclusion: In this early economic model, delandistrogene moxeparvovec increases evLYs versus SoC and begins to inform its potential value from a healthcare perspective.

Multi-Laboratory Evaluation of Prototype Dried Blood Spot Quality Control Materials for Creatine Kinase-MM Newborn Screening Assays

Pilot studies to detect newborns with Duchenne Muscular Dystrophy (DMD) by newborn bloodspot screening (NBS) have been conducted under the New York State Newborn Screening Program (NYS) and are currently in progress as part of the Early Check Program at Research Triangle Institute (RTI) International. The Newborn Screening Quality Assurance Program (NSQAP) at the U.S. Centers for Disease Control and Prevention (CDC) produced a set of seven prototype dried blood spot (DBS) reference materials spiked with varying levels of creatine kinase MM isoform (CK-MM). These DBS were evaluated over a 3-week period by CDC, NYS, and RTI, all using the same CK-MM isoform-specific fluoroimmunoassay. Results from each laboratory were highly correlated with the relative proportion of CK-MM added to each of the six spiked pools. Based on reference ranges established by NYS and RTI for their pilot studies, these contrived DBS collectively spanned the CK-MM ranges found in typical newborns and the elevated ranges associated with DMD. This set allows quality assessment over the wide range of fluctuating CK-MM levels in typical and DMD-affected newborns.

Newborn Screening for the Diagnosis and Treatment of Duchenne Muscular Dystrophy

A pilot newborn screening (NBS) program for Duchenne muscular dystrophy (DMD) study proposes to assess the feasibility of the screening procedure, temporal course of the various steps of screening, and the public acceptability of the program. This is particularly vital to ascertain as DMD is considered a 'non-treatable' disease and thus does not fit the traditional criteria for newborn screening. However, modern perspectives of NBS for DMD are changing and point to possible net benefits for children and their families undertaking NBS for DMD. The aim of this workshop was to establish pathways for the successful implementation and evaluation of a pilot NBS for DMD program in Australia. Consensus was reached as to the rationale for, potential benefits, risks, barriers and facilitators of screening, alongside the establishment of screening protocols and clinical referral pathways.

Update of the Brazilian consensus recommendations on Duchenne muscular dystrophy

In the last few decades, there have been considerable improvements in the diagnosis and care of Duchenne muscular dystrophy (DMD), the most common childhood muscular dystrophy. International guidelines have been published and recently reviewed. A group of Brazilian experts has developed a standard of care based on a literature review with evidence-based graded recommendations in a two-part publication. Implementing best practice management has helped change the natural history of this chronic progressive disorder, in which the life expectancy for children of the male sex in the past used to be very limited. Since the previous publication, diagnosis, steroid treatment, rehabilitation, and systemic care have gained more significant insights with new original work in certain fields. Furthermore, the development of new drugs is ongoing, and some interventions have been approved for use in certain countries. Therefore, we have identified the need to review the previous care recommendations for Brazilian patients with DMD. Our objective was to create an evidence-based document that is an update on our previous consensus on those topics.

Biomarkers in Duchenne Muscular Dystrophy: Current Status and Future Directions

 Duchenne muscular dystrophy is a severe, X-linked disease characterized by decreased muscle mass and function in children. Genetic and biochemical research over the years has led to the characterization of the cause and the pathophysiology of the disease. Moreover, the elucidation of genetic mechanisms underlining Duchenne muscular dystrophy has allowed for the design of innovative personalized therapies.The identification of specific, accurate, and sensitive biomarkers is becoming crucial for evaluating muscle disease progression and response to therapies, disease monitoring, and the acceleration of drug development and related regulatory processes.This review illustrated the up-to-date progress in the development of candidate biomarkers in DMD at the level of proteins, metabolites, micro-RNAs (miRNAs) and genetic modifiers also highlighting the complexity of translating research results to clinical practice.We highlighted the challenges encountered in translating biomarkers into the clinical context and the existing bottlenecks hampering the adoption of biomarkers as surrogate endpoints. These challenges could be overcome by national and international collaborative efforts, multicenter data sharing, definition of public biobanks and patients' registries, and creation of large cohorts of patients. Novel statistical tools/ models suitable to analyze small patient numbers are also required.Finally, collaborations with pharmaceutical companies would greatly benefit biomarker discovery and their translation in clinical trials.

Newborn screening for genetic disorders: Current status and prospects for the future

Newborn screening (NBS) is a public health service aimed at identifying infants with severe genetic disorders, thus providing effective treatment early enough to prevent or ameliorate the onset of symptoms. Current NBS uses biochemical analysis of dried blood spots, predominately with time-resolved fluorescence immunoassay and tandem mass spectrometry, which produces some false positives and false negatives. The application of enzymatic activity-based testing technology provides a reliable screening method for some disorders. Genetic testing is now commonly used for secondary or confirmatory testing after a positive result in some NBS programs. Recently, next-generation sequencing (NGS) has emerged as a robust tool that enables large panels of genes to be scanned together rapidly. Rapid advances in NGS emphasize the potential for genomic sequencing to improve NBS programs. However, some challenges still remain and require solution before this is applied for population screening.

A pilot study of newborn screening for Duchenne muscular dystrophy in Guangzhou

Background

To estimate the overall situation of Duchenne muscular dystrophy (DMD) screening in newborns in Guangzhou, China.

Method

A total of 62553 newborns including 44268 males and 18285 females were screened for DMD by measuring muscle specific creatine kinase isoform (CK-MM) concentrations using the GSP® Neonatal CK-MM kit based on time-resolved immunofluorescence. We recalled positive cases and recollected dried blood spots (DBS) for retest of CK-MM. The newborns with retest positive result were recalled again for serum creatine kinase (CK) and multiplex ligation-dependent probe amplification (MLPA) test. Whole exon sequencing was performed when MLPA test was negative.

Results

Four males were diagnosed with DMD. The incidence of males was 1/11067. No DMD patient was found in female. There were significant differences of CK-MM concentration between male and female newborns. Among gestational age (GA), birth weight (BW) and age at sampling, linear regression analysis showed that CK-MM concentration was much more closely correlated with GA and age at sampling.

Conclusions

CK-MM concentration is affected by gender, GA, BW and age at sampling. The efficiency of DMD screening might be improved by adjusting a multitier cut-off value according to GA and age at sampling. DMD newborn screening should be male priority.

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A total of 62553 newborns including 44268 males and 18285 females were screened for DMD in Guangzhou.

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Four males were diagnosed with DMD. The incidence of males was 1/11067. No DMD patient found in female.

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DMD newborn screening should be male priority.

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The efficiency of DMD screening might be improved by adjusting a multitier cut-off value according to GA and age at sampling.

Newborn Screening for Duchenne Muscular Dystrophy: First Year Results of a Population-Based Pilot

Advancements in therapies for Duchenne muscular dystrophy (DMD) have made diagnosis within the newborn period a high priority. We undertook a consortia approach to advance DMD newborn screening in the United States. This manuscript describes the formation of the Duchenne Newborn Screening Consortium, the development of the pilot protocols, data collection tools including parent surveys, and findings from the first year of a two-year pilot. The DMD pilot design is population-based recruitment of infants born in New York State. Data tools were developed to document the analytical and clinical validity of DMD NBS, capture parental attitudes, and collect longitudinal health information for diagnosed newborns. Data visualizations were updated monthly to inform the consortium on enrollment. After 12 months, 15,754 newborns were screened for DMD by the New York State Newborn Screening (NYS NBS) Program. One hundred and forty screened infants had borderline screening results, and sixteen infants were referred for molecular testing. Three male infants were diagnosed with dystrophinopathy. Data from the first year of a two-year NBS pilot for DMD demonstrate the feasibility of NBS for DMD. The consortia approach was found to be a useful model, and the Newborn Screening Translational Research Network's data tools played a key role in describing the NBS pilot findings and engaging stakeholders.

Duchenne expert physician perspectives on Duchenne newborn screening and early Duchenne care

Duchenne muscular dystrophy (DMD) is a progressive, fatal neuromuscular disorder typically diagnosed between 4 and 5 years of age. DMD currently has five FDA approved therapies, which has led to increased interest in newborn screening (NBS) for DMD. Our objective was to explore the perspectives and predicted practices of physicians (primarily neurologists) who will likely be responsible for the follow-up of infants identified with DMD through NBS. A short survey was developed and distributed to physicians who are responsible for providing care for patients with Duchenne at Certified Duchenne Care Centers across the USA. Twenty-seven physicians responded to statements about benefit and readiness for dystrophinopathy NBS, which care recommendations they would make at initial infant visits, and when they would recommend initiating approved therapies. Most DMD physicians indicated they see benefit in NBS (82%) and believe the DMD care community is ready for NBS in dystrophinopathies (74%). The majority of physicians would recommend multiple interventions, including genetic counseling, maternal carrier testing, referral to early intervention services, screening siblings, discussion of clinical trials, exon skipping therapies, and assessment of social and language development at initial visits. The majority of physicians also indicated they would recommend initiating approved therapies much earlier than the typical age of diagnosis.

Creatine kinase-MM concentration in dried blood spots from newborns and implications for newborn screening for Duchenne muscular dystrophy

Introduction/Aims

Creatine kinase‐MM (CK‐MM) is a marker of skeletal muscle damage. Detection of elevated levels of CK‐MM in newborns can enable an early suspicion of the diagnosis of Duchenne muscular dystrophy (DMD) before symptom onset. Our aim was to investigate CK‐MM levels in DMD‐affected and unaffected newborns using an immunoassay that measures CK‐MM concentration in dried blood spots collected for routine newborn screening.

Methods

To validate the assay in our laboratory, CK‐MM measurements and newborn demographic information were collected for 8584 de‐identified specimens and 15 confirmed DMD patients. After analyzing validation data, CK‐MM normal ranges were determined based on age of newborn at specimen collection. Subsequently, the assay was used to measure CK‐MM concentration in 26 135 newborns as part of a consented pilot study to screen for DMD in New York State. Mean and median levels of CK‐MM based on age of collection, in addition to the 2.5th, 50th, 97.5th, and 99.5th percentiles, were recalculated using the validation and screening data sets.

Results

Median CK‐MM within 1 hour of birth was 109 ng/mL, rose to a high of 499 ng/mL at 25 hours of age, and then declined to 200 ng/mL at 2 days of life. The median continued to decline more slowly and then stabilized at approximately 40 ng/mL at 1 week of life.

Discussion

Because of the marked variability and elevated CK‐MM levels observed within the first days of life, it is important to set multiple CK‐MM age‐related cut‐offs when screening for DMD in newborns.

Newborn screening for Duchenne muscular dystrophy-early detection and diagnostic algorithm for female carriers of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common pediatric-onset form of muscular dystrophy, occurring in 1 in 5,000 live male births. DMD is a multi-system disease resulting in muscle weakness with progressive deterioration of skeletal, heart, and smooth muscle, and learning disabilities. Pathogenic/likely pathogenic (P/LP) variants in the DMD gene, which encodes dystrophin protein, cause dystrophinopathy. All males with a P/LP variant in the X-linked DMD gene are expected to be affected. Two to 20% of female heterozygotes with a P/LP variant develop symptoms of dystrophinopathy ranging from mild muscle weakness to significant disability similar to Becker muscular dystrophy. Recently, with improvements in therapies and testing methodology, there is stronger evidence supporting newborn screening (NBS) for DMD for males and females because females may also develop symptoms. A consented pilot study to screen newborns for DMD was initiated in New York State (NYS) and conducted from 2019 to 2021. The identification of female carriers and the realization of the subsequent uncertainty of providers concerning follow-up during the pilot led to the development of algorithms for screening and diagnosis of carrier females, including both NBS and cascade molecular testing of family members.

Evaluation of the GSP Creatine Kinase-MM Assay and Assessment of CK-MM Stability in Newborn, Patient, and Contrived Dried Blood Spots for Newborn Screening for Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is a fatal X-linked disorder with a birth prevalence of 19.8:100,000 males worldwide. Elevated concentration of the muscle enzyme creatine kinase-MM (CK-MM) allows for presymptomatic screening of newborns using Dried Blood Spots (DBS). We evaluated imprecision and carryover of the FDA-approved PerkinElmer GSP Neonatal CK-MM kit over multiple runs, days, and operators, followed by quantification of CK-MM loss in stored newborn, contrived, and non-newborn patient DBS resulting from exposure to ambient versus low humidity (50-day trial), and high humidity and high temperature (8-day trial). Imprecision %CV was ≤14% for all verification comparisons and over 6 months of testing. On average, the mean CK-MM recovery after 50 days was >80% of initial concentration for all sample types stored in low humidity and <80% in ambient humidity. After 8 days of storage in high humidity and high temperature, the mean recovery for newborn samples was <80%. Verification results for the GSP Neonatal CK-MM assay were concordant with kit parameters and the assay performed consistently over 6 months. CK-MM degradation in ambient storage can be mitigated by reducing exposure to humidity. Assessment of DBS shipping and storage conditions is recommended prior to implementing DMD screening.

Implementation of Hospital-Based Supplemental Duchenne Muscular Dystrophy Newborn Screening (sDMDNBS): A Pathway to Broadening Adoption

Duchenne muscular dystrophy (DMD) is not currently part of mandatory newborn screening, despite the availability of a test since 1975. In the absence of screening, a DMD diagnosis is often not established in patients until 3-6 years of age. During this time, irreversible muscle degeneration takes place, and clinicians agree that the earlier therapy is initiated, the better the long-term outcome. With recent availability of FDA-approved DMD therapies, interest has renewed for adoption by state public health programs, but such implementation is a multiyear process. To speed access to approved therapies, we implemented a unique, hospital-based program offering parents of newborns an optional, supplemental DMD newborn screen (NBS) via a two-tiered approach: utilizing a creatine kinase (CK) enzyme assay coupled with rapid targeted next-generation sequencing (tNGS) for the DMD gene (using a Whole-Exome Sequencing (WES) assay). The tNGS/WES assay integrates the ability to detect both point mutations and large deletion/duplication events. This tiered newborn screening approach allows for the opportunity to improve treatment and outcomes, avoid the diagnostic delays, and diminish healthcare disparities. To implement this screening algorithm through hospitals in a way that would ultimately be acceptable to public health laboratories, we chose an FDA-approved CK-MM immunoassay to avoid the risks of false-negative/-positive results. Because newborn CK values can be affected due to non-DMD-related causes such as birth trauma, a confirmatory repeat CK assay on a later dried blood spot (DBS) collection has been proposed. Difficulties associated with non-routine repeat DBS collection, including the tracking and recall of families, and the potential creation of parental anxiety associated with false-positive results, can be avoided with this algorithm. Whereas a DMD diagnosis is essentially ruled out by the absence of detected DMD sequence abnormalities, a subsequent CK would still be warranted to confirm resolution of the initial elevation, and thus the absence of non-DMD muscular dystrophy or other pathologies. To date, we have screened over 1500 newborns (uptake rate of ~80%) by a CK-MM assay, and reflexed DMD tNGS in 29 of those babies. We expect the experience from this screening effort will serve as a model that will allow further expansion to other hospital systems until a universal public health screening is established.

Creatine kinase test diagnostic accuracy in neonatal screening for Duchenne Muscular Dystrophy: A systematic review

OBJECTIVES

to evaluate the accuracy of the creatine kinase test in neonatal screening for Duchenne Muscular Dystrophy.

METHODS

Investigations were carried out in six databases, gray literature and manual search. All studies and data extraction eligibility processes were carried out in paired mode. The methodological stringency of the studies was assessed using the modified QUADAS 2 tool. The performance measures of the test were calculated using the Meta-DiSc software, version 1.4.

RESULTS

11 studies were included, with a total sample of 1,416,123 newborns. The positive likelihood ratio was more than 10 in these studies. On the other hand, the negative likelihood ratio was up to 0.2 in 9/10 studies; however, when considering the upper limit of the confidence interval, only 4/10 studies showed a negative likelihood ratio less than 0.2 and in 6/11 it was greater than 0.5. Specificity was close to 1 in studies. The sensitivity was equal to or greater than 0.81 in 10/11 studies; however, when considering the reliability's minimum interval limit, only 6/10 studies showed sensitivity equal to or greater than 0.7. Ten studies were summarized on a ROC curve indicating good performance (Area under the curve = 0.9980 and Q index = 0.9846).

CONCLUSIONS

the creatine kinase test showed good accuracy in screening for cases of Duchenne Muscular Dystrophy and may be a useful alternative in the early diagnosis of the disease followed by confirmatory genetic testing.

Newborn screening of duchenne muscular dystrophy specifically targeting deletions amenable to exon-skipping therapy

Duchenne Muscular Dystrophy (DMD) is a lethal progressive muscle-wasting disease. New treatment strategies relying on DMD gene exon-skipping therapy have recently been approved and about 30% of patients could be amenable to exon 51, 53 or 45 skipping. We evaluated the spectrum of deletions reported in DMD registries, and designed a method to screen newborns and identify DMD deletions amenable to exon 51, 53 and 45 skipping. We developed a multiplex qPCR assay identifying hemi(homo)-zygotic deletions of the flanking exons of these therapeutic targets in DMD exons (i.e. exons 44, 46, 50, 52 and 54). We conducted an evaluation of our new method in 51 male patients with a DMD phenotype, 50 female carriers of a DMD deletion and 19 controls. Studies were performed on dried blood spots with patient's consent. We analyzed qPCR amplification curves of controls, carriers, and DMD patients to discern the presence or the absence of the target exons. Analysis of the exons flanking the exon-skipping targets permitted the identification of patients that could benefit from exon-skipping. All samples were correctly genotyped, with either presence or absence of amplification of the target exon. This proof-of-concept study demonstrates that this new assay is a highly sensitive method to identify DMD patients carrying deletions that are rescuable by exon-skipping treatment. The method is easily scalable to population-based screening. This targeted screening approach could address the new management paradigm in DMD, and could help to optimize the beneficial therapeutic effect of DMD therapies by permitting pre-symptomatic care.

Duchenne Muscular Dystrophy: recent advances in protein biomarkers and the clinical application

INTRODUCTION

Early biomarker discovery studies have praised the value of their emerging results, predicting an unprecedented impact on health care. Biomarkers are expected to provide tests with increased specificity and sensitivity compared to existing measures, improve the decision-making process, and accelerate the development of therapies. For rare disorders, like Duchenne Muscular Dystrophy (DMD) such biomarkers can assist the development of therapies, therefore also helping to find a cure for the disease.

AREA COVERED

State-of-the-art technologies have been used to identify blood biomarkers for DMD and efforts have been coordinated to develop and promote translation of biomarkers for clinical practice. Biomarker translation to clinical practice is however, adjoined by challenges related to the complexity of the disease, involving numerous biological processes, and the limited sample resources. This review highlights the current progress on the development of biomarkers, describing the proteomics technologies used, the most promising findings and the challenges encountered.

EXPERT OPINION

Strategies for effective use of samples combined with orthogonal proteomics methods for protein quantification are essential for translating biomarkers to the patient's bed side. Progress is achieved only if strong evidence is provided that the biomarker constitutes a reliable indicator of the patient's health status for a specific context of use.