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.

Time to diagnosis of Duchenne muscular dystrophy remains unchanged: Findings from the Muscular Dystrophy Surveillance, Tracking, and Research Network, 2000-2015

INTRODUCTION/AIMS

With current and anticipated disease-modifying treatments, including gene therapy, an early diagnosis for Duchenne muscular dystrophy (DMD) is crucial to assure maximum benefit. In 2009, a study from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) showed an average diagnosis age of 5 years among males with DMD born from January 1, 1982 to December 31, 2000. Initiatives were implemented by the US Centers for Disease Control and Prevention (CDC) and patient organizations to reduce time to diagnosis. We conducted a follow-up study in a surveillance cohort born after January 1, 2000 to determine whether there has been an improvement in time to diagnosis.

METHODS

We assessed the age of diagnosis among males with DMD born from January 1, 2000 to December 31, 2015 using data collected by six US MD STARnet surveillance sites (Colorado, Iowa, western New York State, the Piedmont region of North Carolina, South Carolina, and Utah). The analytic cohort included 221 males with definite or probable DMD diagnosis without a documented family history. We computed frequency count and percentage for categorical variables, and mean, median, and standard deviation (SD) for continuous variables.

RESULTS

The mean [median] ages in years of diagnostic milestones were: first signs, 2.7 [2.0]; first creatine kinase (CK), 4.6 [4.6]; DNA/muscle biopsy testing, 4.9 [4.8]; and time from first signs to diagnostic confirmation, 2.2 [1.4].

DISCUSSION

The time interval between first signs of DMD and diagnosis remains unchanged at 2.2 years. This results in lost opportunities for timely genetic counseling, implementation of standards of care, initiation of glucocorticoids, and participation in clinical trials.

Direct costs of adhering to selected Duchenne muscular dystrophy care considerations: estimates from a Midwestern state

INTRODUCTION/AIMS

The multidisciplinary Duchenne muscular dystrophy (DMD) Care Considerations were developed to standardize care and improve outcomes. We provide cumulative cost estimates for selected key preventive (i.e., excluding new molecular therapies and acute care) elements of the care considerations in eight domains (neuromuscular, rehabilitation, respiratory, cardiac, orthopedic, gastrointestinal, endocrine, psychosocial management) independent of completeness of uptake or provision of non-preventive care.

METHODS

We used de-identified insurance claims data from a large Midwestern commercial health insurer during 2018. We used Current Procedural Terminology and National Drug codes to extract unit costs for clinical encounters representing key preventive elements of the DMD Care Considerations. We projected per-patient cumulative costs from ages 5 to 25 years for these elements by multiplying a schedule of recommended frequencies of preventive services by unit costs in 2018 US dollars.

RESULTS

Assuming a diagnosis at age 5 years, independent ambulation until age 11, and survival until age 25, we estimated 670 billable clinical events. The 20-year per-patient cumulative cost was $174,701 with prednisone ($2.3 million with deflazacort) and an expected total of $12,643 ($29,194) for out-of-pocket expenses associated with those events and medications.

DISCUSSION

Standardized monitoring of disease progression and treatments may reduce overall costs of illness. Costs associated with these services would be needed to quantify potential savings. Our approach demonstrates a method to estimate costs associated with implementation of preventive care schedules.

Differentiation of Pediatric-Onset Duchenne and Becker Muscular Dystrophy Subphenotypes Using Data from the Muscular Dystrophy Surveillance Tracking and Research Network (MD STARnet)

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) phenotypes are used to describe disease progression in affected individuals. However, considerable heterogeneity has been observed across and within these two phenotypes, suggesting a spectrum of severity rather than distinct conditions. Characterizing the phenotypes and subphenotypes aids researchers in the design of clinical studies and clinicians in providing anticipatory guidance to affected individuals and their families. Using data from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet), we used K-means cluster analysis to group phenotypically similar males with pediatric-onset dystrophinopathy. We identified four dystrophinopathy clusters: Classical BMD, Classical DMD, late ambulatory DMD, and severe DMD. The clusters that we identified align with both 'classical' and 'non-classical' dystrophinopathy described in the literature. Individuals with dystrophinopathies have heterogenous clinical presentations that cluster into phenotypically similar groups. Use of clinically-derived phenotyping may provide a clearer understanding of disease trajectories, reduce variability in study results, and prevent exclusion of certain cohorts from analysis. Findings from studying subphenotypes may ultimately improve our ability to predict disease progression.

Characteristics of Clinical Trial Participants with Duchenne Muscular Dystrophy: Data from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet)

BACKGROUND

Therapeutic trials are critical to improving outcomes for individuals diagnosed with Duchenne muscular dystrophy (DMD). Understanding predictors of clinical trial participation could maximize enrollment.

METHODS

Data from six sites (Colorado, Iowa, Piedmont region North Carolina, South Carolina, Utah, and western New York) of the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) were analyzed. Clinical trial participation and individual-level clinical and sociodemographic characteristics were obtained from medical records for the 2000-2015 calendar years. County-level characteristics were determined from linkage of the most recent county of residence identified from medical records and publicly available federal datasets. Fisher's exact and Wilcoxon two-sample tests were used with statistical significance set at one-sided p-value (<0.05) based on the hypothesis that nonparticipants had fewer resources.

RESULTS

Clinical trial participation was identified among 17.9% (MD STARnet site: 3.7-27.3%) of 358 individuals with DMD. Corticosteroids, tadalafil, and ataluren (PTC124) were the most common trial medications recorded. Fewer non-Hispanic blacks or Hispanics than non-Hispanic whites participated in clinical trials. Trial participants tended to reside in counties with lower percentages of non-Hispanic blacks. Conclusion: Understanding characteristics associated with clinical trial participation is critical for identifying participation barriers and generalizability of trial results. MD STARnet is uniquely able to track clinical trial participation through surveillance and describe patterns of participation.

Association of genetic mutations and loss of ambulation in childhood-onset dystrophinopathy

BACKGROUND

Quantifying associations between genetic mutations and loss of ambulation (LoA) among males diagnosed with childhood-onset dystrophinopathy is important for understanding variation in disease progression and may be useful in clinical trial design.

METHODS

Genetic and clinical data from the Muscular Dystrophy Surveillance, Tracking, and Research Network for 358 males born and diagnosed from 1982 to 2011 were analyzed. LoA was defined as the age at which independent ambulation ceased. Genetic mutations were defined by overall type (deletion/duplication/point mutation) and among deletions, those amenable to exon-skipping therapy (exons 8, 20, 44-46, 51-53) and another group. Cox proportional hazards regression modeling was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Mutation type did not predict time to LoA. Controlling for corticosteroids, Exons 8 (HR = 0.22; 95% CI = 0.08, 0.63) and 44 (HR = 0.30; 95% CI = 0.12, 0.78) were associated with delayed LoA compared to other exon deletions.

CONCLUSIONS

Delayed LoA in males with mutations amenable to exon-skipping therapy is consistent with previous studies. These findings suggest that clinical trials including exon 8 and 44 skippable males should consider mutation information prior to randomization.

Characterization of individuals with selected muscular dystrophies from the expanded pilot of the Muscular Dystrophy Surveillance, Tracking and Research Network (MD STARnet) in the United States

INTRODUCTION

Data on muscular dystrophies (MDs), a heterogeneous group of heritable diseases hallmarked by progressive muscle deterioration, are scarce.

OBJECTIVE

We describe cross-sectional sociodemographic and clinical characteristics of individuals with congenital, distal, Emery-Dreifuss, facioscapulohumeral, limb-girdle, myotonic, or oculopharyngeal MD.

METHODS

The study was conducted in four sites (Arizona, Colorado, Iowa, and 12 western New York counties) as a pilot expansion of the Muscular Dystrophy Surveillance, Tracking and Research Network, funded by the Centers for Disease Control and Prevention. MDs were detected in healthcare facilities and administrative data sources using International Classification of Disease codes. Our sample contains 1,723 individuals with a MD diagnosis and a healthcare encounter between January 1, 2007 and December 31, 2011.

RESULTS AND CONCLUSIONS

Individuals were mostly non-Hispanic and white. Median ages ranged from 9.2 to 66.0 years. Most (98%) had health insurance. The proportion of individuals who were disabled or unable to work increased with age (range: 8.6-46.4%). People with limb-girdle MD aged ≥18 years were more likely to be nonambulatory (range: 24.5-44.7%). The percentages of individuals with documented clinical interventions during the surveillance period were low. The most common cause of death was respiratory causes (46.3-57.1%); an ICD-10 code for MD (G71.1 or G71.0) was reported for nearly one-half. Our findings show wide variability in sociodemographic and clinical characteristics across MDs.

Using an Online, Modified Delphi Approach to Engage Patients and Caregivers in Determining the Patient-Centeredness of Duchenne Muscular Dystrophy Care Considerations

Purpose. To determine the patient-centeredness of endocrine and bone health Duchenne muscular dystrophy (DMD) care considerations using the RAND/PPMD Patient-Centeredness Method (RPM), which is a novel, online, modified-Delphi approach to engaging patients and caregivers in clinical guideline development. Methods. We solicited input on the patient-centeredness of care considerations from 28 individuals with DMD and 94 caregivers, randomly assigned to 1 of 2 mixed panels. During a 3-round online modified-Delphi process, participants rated the importance and acceptability of 19 DMD care considerations (round 1), reviewed and discussed the initial results (round 2), and revised their original ratings (round 3). Patient-centeredness was operationalized as importance and acceptability of recommendations. We considered a care consideration to be patient-centered if both panels deemed it important and acceptable. Results. Ninety-five panelists (78%) participated in this study. Of these, 88 (93%) participated in round 1, 74 (78%) in round 2, and 56 (59%) in round 3. Panelists deemed 12 care considerations to be patient-centered: 3 weight management, 3 bone health, 4 vertical growth, and 2 puberty recommendations. Seven care considerations did not meet patient-centeredness criteria. Common reasons were lack of evidence specific to DMD and concerns about insurance coverage, access to treatment, and patient safety. Conclusions. Using the RPM, Duchenne families considered most care considerations to be patient-centered. Besides being clinically appropriate, these considerations are likely to be consistent with the preferences, needs, and values of Duchenne families. While all relevant care considerations should be discussed during patient-provider encounters, those that did not meet patient-centeredness criteria in particular should be carefully considered as part of joint decision making between Duchenne families and their providers. Study Registration: HSRProj 20163126.

Diagnostic Accuracy of Phenotype Classification in Duchenne and Becker Muscular Dystrophy Using Medical Record Data1

Dystrophinopathies are caused by mutations in DMD resulting in progressive muscle weakness. They are historically divided into the more severe Duchenne (DMD) and milder Becker (BMD) muscular dystrophy phenotypes. Classification is important for research and clinical care. The purpose of this study was to describe a multi-variable approach to classifying cases from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) and to assess the accuracy of the diagnostic classification scheme. We used age at loss of mobility, molecular testing results, and age at symptom onset to classify cases as having DMD or BMD and to assess sensitivity and specificity. Mobility status showed low sensitivity and high specificity for predicting DMD (65.5% and 99.3%, respectively) and BMD (62.8% and 97.7%, respectively) phenotypes. Molecular testing showed 90.9% sensitivity and 66.4% specificity for DMD; 76.3% sensitivity and 90.0% specificity for BMD. Age of onset predicted DMD with sensitivity of 73.9% and specificity of 69.0%; BMD had 99.7% specificity and 36.7% sensitivity. Mobility status, molecular test results, and age at symptom onset are important but inconsistent measures for accurately classifying individuals into DMD or BMD phenotypes. These results have implications for prognosis in newly diagnosed individuals and for classifying phenotype in clinical trials.

Gender difference in clinical conditions among hospitalized adults with myotonic dystrophy

INTRODUCTION

In this study we examined gender differences in adult hospitalizations with myotonic dystrophy (DM).

METHODS

From the Nationwide Inpatient Sample (NIS) 2010-2014, we identified 1,891 adult hospitalizations with a DM diagnosis and constructed a comparison group of hospitalizations without DM using propensity score matching. We calculated relative risk by gender for 44 clinical diagnoses that each accounted for at least 5% of DM hospitalizations.

RESULTS

Hospitalizations with DM were longer (4.8 vs. 4.1 days, P < 0.0001) and more costly ($13,241 vs. $11,458, P < 0.0001) than those without DM. More than half (25 of 44) of the conditions co-occurring with DM hospitalizations did not differ in their relative risks by gender. For those that differed by gender, only 5 were specific to DM, compared with hospitalizations without DM.

DISCUSSION

Our findings highlight the importance of comprehensive and coordinated care for DM rather than gender-oriented care in the inpatient setting. Muscle Nerve 59:348-353, 2019.

Evaluating Implementation of the Updated Care Considerations for Duchenne Muscular Dystrophy

Care Considerations for Duchenne Muscular Dystrophy were published in 2010. However, little is known about the extent to which these considerations were implemented after publication. With this article, we provide direction on evaluating the uptake of the 2018 Duchenne Muscular Dystrophy Care Considerations. We identify key elements of care and present suggestions for their use in evaluation and research.

Muscular Dystrophy Surveillance, Tracking, and Research Network pilot: Population-based surveillance of major muscular dystrophies at four U.S. sites, 2007-2011

BACKGROUND

For 10 years, the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) conducted surveillance for Duchenne and Becker muscular dystrophy (DBMD). We piloted expanding surveillance to other MDs that vary in severity, onset, and sources of care.

METHODS

Our retrospective surveillance included individuals diagnosed with one of nine eligible MDs before or during the study period (January 2007-December 2011), one or more health encounters, and residence in one of four U.S. sites (Arizona, Colorado, Iowa, or western New York) at any time within the study period. We developed case definitions, surveillance protocols, and software applications for medical record abstraction, clinical review, and data pooling. Potential cases were identified by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes 359.0, 359.1, and 359.21 and International Classification of Diseases, Tenth Revision (ICD-10) codes G71.0 and G71.1. Descriptive statistics were compared by MD type. Percentage of MD cases identified by each ICD-9-CM code was calculated.

RESULTS

Of 2,862 cases, 32.9% were myotonic, dystrophy 25.8% DBMD, 9.7% facioscapulohumeral MD, and 9.1% limb-girdle MD. Most cases were male (63.6%), non-Hispanic (59.8%), and White (80.2%). About, half of cases were genetically diagnosed in self (39.1%) or family (6.2%). About, half had a family history of MD (48.9%). The hereditary progressive MD code (359.1) was the most common code for identifying eligible cases. The myotonic code (359.21) identified 83.4% of eligible myotonic dystrophy cases (786/943).

CONCLUSIONS

MD STARnet is the only multisite, population-based active surveillance system available for MD in the United States. Continuing our expanded surveillance will contribute important epidemiologic and health outcome information about several MDs.

Diagnosis and management of Duchenne muscular dystrophy, part 3: primary care, emergency management, psychosocial care, and transitions of care across the lifespan

Improvements in the function, quality of life, and longevity of patients with Duchenne muscular dystrophy (DMD) have been achieved through a multidisciplinary approach to management across a range of health-care specialties. In part 3 of this update of the DMD care considerations, we focus on primary care, emergency management, psychosocial care, and transitions of care across the lifespan. Many primary care and emergency medicine clinicians are inexperienced at managing the complications of DMD. We provide a guide to the acute and chronic medical conditions that these first-line providers are likely to encounter. With prolonged survival, individuals with DMD face a unique set of challenges related to psychosocial issues and transitions of care. We discuss assessments and interventions that are designed to improve mental health and independence, functionality, and quality of life in critical domains of living, including health care, education, employment, interpersonal relationships, and intimacy.

Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management

Since the publication of the Duchenne muscular dystrophy (DMD) care considerations in 2010, multidisciplinary care of this severe, progressive neuromuscular disease has evolved. In conjunction with improved patient survival, a shift to more anticipatory diagnostic and therapeutic strategies has occurred, with a renewed focus on patient quality of life. In 2014, a steering committee of experts from a wide range of disciplines was established to update the 2010 DMD care considerations, with the goal of improving patient care. The new care considerations aim to address the needs of patients with prolonged survival, to provide guidance on advances in assessments and interventions, and to consider the implications of emerging genetic and molecular therapies for DMD. The committee identified 11 topics to be included in the update, eight of which were addressed in the original care considerations. The three new topics are primary care and emergency management, endocrine management, and transitions of care across the lifespan. In part 1 of this three-part update, we present care considerations for diagnosis of DMD and neuromuscular, rehabilitation, endocrine (growth, puberty, and adrenal insufficiency), and gastrointestinal (including nutrition and dysphagia) management.

Secondary Conditions Among Males With Duchenne or Becker Muscular Dystrophy

Duchenne and Becker muscular dystrophy are X-linked neuromuscular disorders characterized by progressive muscle degeneration. Despite the involvement of multiple systems, secondary conditions among affected males have not been comprehensively described. Two hundred nine caregivers of affected males (aged 3-31 years) identified by the Muscular Dystrophy Surveillance, Tracking, and Research Network completed a mailed survey that included questions about secondary conditions impacting multiple body functions. The 5 most commonly reported conditions in males with Duchenne were cognitive deficits (38.4%), constipation (31.7%), anxiety (29.3%), depression (27.4%), and obesity (19.5%). Higher frequencies of anxiety, depression, and kidney stones were found among nonambulatory males compared to ambulatory males. Attention-deficit hyperactivity disorder (ADHD) was more common in ambulatory than nonambulatory males. These data support clinical care recommendations for monitoring of patients with Duchenne or Becker muscular dystrophy by a multidisciplinary team to prevent and treat conditions that may be secondary to the diagnosis.

Clinical Follow-Up for Duchenne Muscular Dystrophy Newborn Screening: A Proposal

New developments in the rapid diagnosis and treatment of boys with Duchenne muscular dystrophy (DMD) have led to growing enthusiasm for instituting DMD newborn screening (NBS) in the United States. Our group has been interested in developing clinical guidance to be implemented consistently in specialty care clinics charged with the care of presymptomatically identified newborns referred after DMD-NBS. We reviewed the existing literature covering patient-centered clinical follow-up after NBS, educational material from public health and advocacy sites, and federal recommendations on effective NBS follow-up. We discussed the review as a group and added our own experience to develop materials suitable for initial parent and primary care provider education. These materials and a series of templates for subspecialist encounters could be used to provide consistent care across centers and serve as the basis for ongoing quality improvement. Muscle Nerve 54: 186-191, 2016.

Hospitalizations and emergency room visits for adolescents and young adults with muscular dystrophy living in South Carolina

INTRODUCTION

Transitioning from adolescence to adulthood can be problematic for individuals with rare disabilities such as muscular dystrophy (MD).

METHODS

We identified a cohort of 220 individuals with MD and 440 matched comparison individuals and measured emergency room (ER) and inpatient (IP) encounters for the years 2000 through 2010, using all-payer hospital discharge uniform billing data. We compared ER and IP use rates for people with and without MD, and for 15-19-year-olds with MD to 20-24-year-olds with MD.

RESULTS

ER and IP use rates were significantly higher among individuals with MD than the comparison group. In addition, ER and IP use rates were significantly higher in the 20-24-year age group than in the 15-19-year group.

CONCLUSIONS

Additional research is needed to determine whether increased ER and IP use in young adults is attributable to difficulties in healthcare transition versus increased disease severity.

Prevalence of Duchenne and Becker muscular dystrophies in the United States

OBJECTIVE

To estimate prevalence of childhood-onset Duchenne and Becker muscular dystrophies (DBMD) in 6 sites in the United States by race/ethnicity and phenotype (Duchenne muscular dystrophy [DMD] or Becker muscular dystrophy [BMD]).

METHODS

In 2002, the Centers for Disease Control and Prevention established the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) to conduct longitudinal, population-based surveillance and research of DBMD in the United States. Six sites conducted active, multiple-source case finding and record abstraction to identify MD STARnet cases born January 1982 to December 2011. We used cross-sectional analyses to estimate prevalence of DBMD per 10 000 boys, ages 5 to 9 years, for 4 quinquennia (1991-1995, 1996-2000, 2001-2005, and 2006-2010) and prevalence per 10 000 male individuals, ages 5 to 24 years, in 2010. Prevalence was also estimated by race/ethnicity and phenotype.

RESULTS

Overall, 649 cases resided in an MD STARnet site during ≥1 quinquennia. Prevalence estimates per 10 000 boys, ages 5 to 9 years, were 1.93, 2.05, 2.04, and 1.51, respectively, for 1991-1995, 1996-2000, 2001-2005, and 2006-2010. Prevalence tended to be higher for Hispanic individuals than non-Hispanic white or black individuals, and higher for DMD than BMD. In 2010, prevalence of DBMD was 1.38 per 10 000 male individuals, ages 5 to 24 years.

CONCLUSIONS

We present population-based prevalence estimates for DBMD in 6 US sites. Prevalence differed by race/ethnicity, suggesting potential cultural and socioeconomic influences in the diagnosis of DBMD. Prevalence also was higher for DMD than BMD. Continued longitudinal surveillance will permit us to examine racial/ethnic and socioeconomic differences in treatment and outcomes for MD STARnet cases.

Measuring quality of life in muscular dystrophy

OBJECTIVES

The objectives of this study were to develop a conceptual model of quality of life (QOL) in muscular dystrophies (MDs) and review existing QOL measures for use in the MD population.

METHODS

Our model for QOL among individuals with MD was developed based on a modified Delphi process, literature review, and input from patients and patient advocacy organizations. Scales that have been used to measure QOL among patients with MD were identified through a literature review and evaluated using the COSMIN (Consensus-Based Standards for the Selection of Health Measurement Instruments) checklist.

RESULTS

The Comprehensive Model of QOL in MD (CMQM) captures 3 broad domains of QOL (physical, psychological, and social), includes factors influencing self-reported QOL (disease-related factors, support/resources, and expectations/aspirations), and places these concepts within the context of the life course. The literature review identified 15 QOL scales (9 adult and 6 pediatric) that have been applied to patients with MD. Very few studies reported reliability data, and none included data on responsiveness of the measures to change in disease progression, a necessary psychometric property for measures included in treatment and intervention studies. No scales captured all QOL domains identified in the CMQM model.

CONCLUSIONS

Additional scale development research is needed to enhance assessment of QOL for individuals with MD. Item banking and computerized adaptive assessment would be particularly beneficial by allowing the scale to be tailored to each individual, thereby minimizing respondent burden.

Reproductive patterns among mothers of males diagnosed with Duchenne or Becker muscular dystrophy

Diagnosis of a child with Duchenne or Becker muscular dystrophy (DBMD) may impact future maternal reproductive choice; however, little is known about the reproductive patterns of mothers with a male child diagnosed with DBMD. Using population-based surveillance data collected by the muscular dystrophy surveillance, tracking, and research network, the proportion of mothers who conceived and delivered a live birth following the diagnosis of DBMD in an affected male child and factors associated with such reproductive choice were identified. To accomplish this, maternal demographic data were linked to birth certificate data to construct the reproductive history for 239 mothers. Univariable and bivariable analyses were conducted to determine the proportion of mothers delivering a live birth and associated factors. By the time of the current study, 96 (40.2%) of the 239 mothers had at least one live birth following delivery of their oldest affected male child; 53 (22.2%) of these mothers had a live birth before and 43 (18.0%) had a live birth after DBMD diagnosis of a male child. Mothers with a live birth after diagnosis were significantly younger at diagnosis of the oldest affected male child (26.2 ± 4.2 years vs. 31.5 ± 5.5 years), and were less likely to be white non-Hispanic compared to those with no live birth after diagnosis. These results suggest that about one in five mothers deliver a live birth subsequent to DBMD diagnosis in a male child. Maternal age and race/ethnicity were associated with this reproductive choice.

Clinic-based infant screening for duchenne muscular dystrophy: a feasibility study

Purpose. The purpose of this study was to assess the desirability of Duchenne muscular dystrophy (DMD) screening, the effectiveness of the consent process, and the feasibility of conducting DMD screening in a pediatric office. Methods. Infant males who attended a 12-month routine well-child visit at a participating pediatric clinic were screened for DMD. Parents and providers completed post-screening questionnaires to assess their experiences with and attitudes toward screening. Results. A total of 264 male infants were screened for DMD. Approximately 78% of parents indicated support of voluntary DMD screening and 91% of providers were in favor of screening for DMD. About 75% of parents correctly answered three of five questions testing their knowledge of DMD screening. Conclusion. DMD screening is feasible in a pediatric office when conducted as part of a research study. Infant screening for DMD eventually could be offered in pediatric health care provider offices as an optional public health service outside of newborn screening.

Recommendations from Multi-disciplinary Focus Groups on Cascade Testing and Genetic Counseling for Fragile X-associated Disorders

The purpose of this paper is to report the outcome of a collaborative project between the Fragile X Research and Treatment Center at the Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute at the University of California at Davis, the National Fragile X Foundation (NFXF), and the Centers for Disease Control and Prevention (CDC). The objective of this collaboration was to develop and disseminate protocols for genetic counseling and cascade testing for the multiple disorders associated with the fragile X mental retardation 1 (FMR1) mutation. Over the last several years, there has been increasing insight into the phenotypic range associated with both the premutation and the full mutation of the FMR1 gene. To help develop recommendations related to screening for fragile X-associated disorders, four, two day advisory focus group meetings were conducted, each with a different theme. The four themes were: (1) fragile X-associated tremor/ataxia syndrome (FXTAS); (2) premature ovarian failure (POF) and reproductive endocrinology; (3) psychiatric, behavioral and psychological issues; and (4) population screening and related ethical issues.

Anaesthesia for liver transplantation in a patient with methylmalonic acidaemia

Liver transplantation is an accepted modality of treatment in some patients with inborn errors of metabolism. We present a child with methylmalonic acidaemia who had successful liver transplantation. The pathophysiology, medical and anaesthetic managements are discussed.

In vitro interaction of cisplatin and fosfomycin on squamous cell carcinoma cultures

OBJECTIVE

Fosfomycin has been shown to be otoprotective and nephroprotective against cisplatin-induced toxic reactions. This study tests whether fosfomycin inhibits the anticancer effect of cisplatin.

METHODS

Three squamous cell carcinoma cell lines were used to determine the effect of fosfomycin on cisplatin-induced tumoricidal activity. Cells were grown in 96 well plates with fosfomycin alone, cisplatin alone, or fosfomycin and cisplatin together. Cell survival was then measured by a colorimetric technique using 3-4,5-dimethylthiazol-2-yl 2,5 diphenyltetrazolium bromide (MTT).

RESULTS

There was no decrease in the effectiveness of cisplatin in killing human squamous cell carcinoma in vitro when fosfomycin was present in concentrations of up to 400 mg/L. One cell line also showed killing at high concentrations of cisplatin, but not at low concentrations.

CONCLUSIONS

Fosfomycin protects against cisplatin-induced toxic reactions and does not inhibit tumoricidal activity in vitro. In addition, one cell line showed relative resistance to cisplatin at low doses, but was effectively killed with high doses of cisplatin. This is the ideal situation for use of fosfomycin so that higher doses of cisplatin may be given with renal and otologic protection.

Cytokine regulation of murine leishmaniasis: interleukin 4 is not sufficient to mediate progressive disease in resistant C57BL/6 mice

Neutralization of interleukin 4 (IL-4) at the time of infection with Leishmania major allowed susceptible BALB/c mice to heal. Recombinant IL-4, however, had little effect on the course of L. major infection in resistant C57BL/6 mice, nor did coinfection with Nippostrongylus brasiliensis, despite marked elevation of endogenous IL-4 levels.

The zeta potential of synthetic sapphire

In contrast to powdered specimens, bulk samples of synthetic sapphire do not exhibit an isoelectric point even at pH as low as 1.65.

The Rheology of Kaolinite suspensions

The rheological properties of constant volume concentration kaolinite suspensions were measured and compared with ζ-potential measurements already made. The correlation is good and the results are interpreted on the basis of the existence of both positive and negative areas on the clay surfaces linking the particles together in " bipolar " flocculation ; these floccules uncoil with increasing neutralization of the H-clay, then at the equivalence point the positive areas are neutralized, the clay suspension deflocculated and the viscosity considerably reduced.

The surface conductance of kaolinite

The surface conductance of kaolinite particles has been determined and compared with values calculated from measured ζ-potentials. A reasonable measure of agreement between these values suggests that the theory is adequate, and indicates that further information about the behaviour of kaolinite suspensions might be gained from careful measurements of this phenomenon. The information can also be used to determine the axial ratios of clay particles.

The ζ-Potential of Kaolinite Particles

Electrophoretic mobility measurements, and both conductometric and potentiometric titrations, were carried out on a kaolinite suspension throughout its neutralization by various bases. The concentration of the ionic species present was calculated from the conductometric and potentiometric titrations, and the true ζ-potential calculated from the electrophoretic mobility by Stigter and Mysels's (1955) method. The results indicate that a discontinuity exists in the adsorption of ions in the vicinity of pH 6.5-7.0 causing a considerable increase in the surface charge density of the particles.

Charge densities and surface conductances at solid-solution interfaces

Surface charge densities for the minerals quartz (SiO2), corundum (Al2O3), rutile (TiO2), cassiterite (SnO2), and haematite (Fe2O3) have been calculated using an equation based on the kinetic theory of the diffuse layer, and requiring a knowledge of ζ-potentials. 111 addition, an equation, which avoids the difficulties of earlier expressions of the kind, has been derived enabling calculation of surface charge densities from surface conductances. Values obtained from the second equation for Fe2O3, SnO2, and TiO2 were much in excess of those calculated from ζ-potentials. The discrepancies have been attributed to considerable contribution of solid conductance to the measured surface conductance. Equations have also been derived permitting calculation of quantities characteristic of the physical properties of the porous plug packings used in the investigations.