Genetics of kidney disorders in Phelan-McDermid syndrome: evidence from 357 registry participants

BACKGROUND

Phelan-McDermid syndrome (PMS) is a rare genetic disorder caused by SHANK3 pathogenic variants or chromosomal rearrangements affecting the chromosome 22q13 region. Previous research found that kidney disorders, primarily congenital anomalies of the kidney and urinary tract, are common in people with PMS, yet research into candidate genes has been hampered by small study sizes and lack of attention to these problems.

METHODS

We used a cohort of 357 people from the Phelan-McDermid Syndrome Foundation International Registry to investigate the prevalence of kidney disorders in PMS using a cross-sectional design and to identify 22q13 genes contributing to these disorders.

RESULTS

Kidney disorders reported included vesicoureteral reflux (n = 37), hydronephrosis (n = 36), dysplastic kidneys (n = 19), increased kidney size (n = 19), polycystic kidneys (15 cases), and kidney stones (n = 4). Out of 315 subjects with a 22q13 deletion, 101 (32%) had at least one kidney disorder, while only one out of 42 (2%) individuals with a SHANK3 pathogenic variant had a kidney disorder (increased kidney size). We identified two genomic regions that were significantly associated with having a kidney disorder with the peak associations observed near positions approximately 5 Mb and 400 Kb from the telomere.

CONCLUSIONS

The candidate genes for kidney disorders include FBLN1, WNT7B, UPK3A, CELSR1, and PLXNB2. This study demonstrates the utility of patient registries for uncovering genetic contributions to rare diseases. Future work should focus on functional studies for these genes to assess their potential pathogenic contribution to the different subsets of kidney disorders.

SARS-CoV-2 emergency use authorization published sensitivity differences do not correlate with positivity rate in a hospital/reference laboratory setting

During the first year of the COVID-19 pandemic skyrocketing demand for testing in the United States, coupled with supply chain issues, necessitated the use of multiple SARS-CoV-2 molecular testing platforms at many health centers. At our institution these platforms consisted of 8 ordered services for sample triage, using 9 emergency use authorized (EUA) SARS-CoV-2 RNA nucleic acid amplification tests resulting in 10 possible ordered service/EAU combinations. Here we review the results of the first ∼2.9 million samples tested and note the variability in positivity rates. We conclude that differences in reported limit of detection did not translate to differences in positivity rate or show correlation to discordant results observed. This highlights the importance of balancing patient testing capacity needs with the desire to have more sensitive tests.

Brain Gene Co-Expression Network Analysis Identifies 22q13 Region Genes Associated with Autism, Intellectual Disability, Seizures, Language Impairment, and Hypotonia

Phelan-McDermid syndrome (PMS) is a rare genetic neurodevelopmental disorder caused by 22q13 region deletions or SHANK3 gene variants. Deletions vary in size and can affect other genes in addition to SHANK3. PMS is characterized by autism spectrum disorder (ASD), intellectual disability (ID), developmental delays, seizures, speech delay, hypotonia, and minor dysmorphic features. It is challenging to determine individual gene contributions due to variability in deletion sizes and clinical features. We implemented a genomic data mining approach for identifying and prioritizing the candidate genes in the 22q13 region for five phenotypes: ASD, ID, seizures, language impairment, and hypotonia. Weighted gene co-expression networks were constructed using the BrainSpan transcriptome dataset of a human brain. Bioinformatic analyses of the co-expression modules allowed us to select specific candidate genes, including EP300, TCF20, RBX1, XPNPEP3, PMM1, SCO2, BRD1, and SHANK3, for the common neurological phenotypes of PMS. The findings help understand the disease mechanisms and may provide novel therapeutic targets for the precise treatment of PMS.

Lymphedema is associated with CELSR1 in Phelan-McDermid syndrome

Lymphedema is a troubling condition present in many disorders including the rare genetic disorder known as Phelan-McDermid syndrome (PMS). The neurobehavioral features of PMS, also known as 22q13.3 deletion syndrome, have been investigated, but little research exists on lymphedema in PMS. In this investigation, clinical and genetic data from 404 people with PMS were reviewed from the PMS-International Registry revealing a prevalence of 5% with lymphedema. Lymphedema was reported in 1 out of 47 people (2.1%) with PMS due to a SHANK3 variant and 19 out of 357 people (5.3%) with PMS due to 22q13.3 deletions. Lymphedema was more common among those in their teens or adulthood (p = 0.0011) and those with deletions >4 Mb. People with lymphedema had significantly larger deletions (mean 5.375 Mb) than those without lymphedema (mean 3.464 Mb, p = 0.00496). Association analysis identified a deletion of the CELSR1 gene to be the biggest risk factor (OR = 12.9 95% CI [2.9-56.2]). Detailed assessment of 5 subjects identified all had deletions of CELSR1, developed symptoms of lymphedema starting at age 8 or older, and typically responded well to standard therapy. In conclusion, this is the largest assessment of lymphedema in PMS to date and our results suggest that individuals with deletions >4 Mb or those with CELSR1 deletions should be assessed for lymphedema.

Weight Loss Is a Strong Predictor of Memory Disorder Independent of Genetic Influences

BACKGROUND

Past studies identified a link between weight loss and dementia, but lacked consistent conclusions. We sought to establish this link by examining the weight change profiles before and after dementia diagnosis.

METHODS

Using data from the Health and Retirement Study (1996-2020), we examined 13,123 participants. We conducted a nested case-control analysis to assess differences in biennial weight change profile while controlling for BMI, longevity polygenic risk scores, and APOE gene variants.

RESULTS

Participants with a memory disorder lost weight (-0.63%) biennially, whereas those without a diagnosis did not (+0.013%, p-value < 0.0001). Our case-control study shows a significant difference (p-value < 0.01) in pre-dementia % weight changes between the cases (-0.29%) and controls (0.19%), but not in post-dementia weight changes. The weight loss group have the highest risk (OR = 2.01; p-value < 0.0001) of developing a memory disorder compared to the stable weight and weight gain groups. The observations hold true after adjusting for BMI, longevity polygenic risk scores, and APOE variant in a multivariable model.

CONCLUSIONS

We observe that weight loss in dementia is a physiological process independent of genetic factors associated with BMI and longevity. Pre-dementia weight loss may be an important prognostic criterion to assess a person's risk of developing a memory disorder.

Sleep disturbances in Phelan-McDermid syndrome: Clinical and metabolic profiling of 56 individuals

Phelan-McDermid Syndrome (PMS) is caused by deletions at chromosome 22q13.3 or pathogenic/likely pathogenic SHANK3 variants. The clinical presentation is extremely variable and includes global developmental delay/intellectual disability (ID), seizures, neonatal hypotonia, and sleep disturbances, among others. This study investigated the prevalence of sleep disturbances, and the genetic and metabolic features associated with them, in a cohort of 56 individuals with PMS. Sleep data were collected via standardized observer/caregiver questionnaires, while genetic data from array-CGH and sequencing of 9 candidate genes within the 22q13.3 region, and metabolic profiling utilized the Biolog Phenotype Mammalian MicroArray plates. Sleep disturbances were present in 64.3% of individuals with PMS, with the most common problem being waking during the night (39%). Sleep disturbances were more prevalent in individuals with a SHANK3 pathogenic variant (89%) compared to subjects with 22q13.3 deletions of any size (59.6%). Distinct metabolic profiles for individuals with PMS with and without sleep disturbances were also identified. These data are helpful information for recognizing and managing sleep disturbances in individuals with PMS, outlining the main candidate gene for this neurological manifestation, and highlighting potential biomarkers for early identification of at-risk subjects and molecular targets for novel treatment approaches.

Preanalytic and Analytic Quality System Considerations in Noncoding RNA Biomarker Development for Clinical Diagnostics

A frequent topic of biomedical research is the potential clinical use of non-coding (nc) RNAs as quantitative biomarkers for a broad spectrum of health and disease. However, ncRNA analyses have not been pressed into widespread diagnostic use. Strong preclinical evidence suggests obstacles in the translation and reproducibility of this type of biomarker which may result from preanalytical and analytical variation in the non-standardized processes used to collect, process, and store samples, as well as the substantive differences between small and long ncRNA. We performed a narrative review of selected literature, through the lens of key laboratory-developed test (LDT) regulations under the Clinical Laboratory Improvement Amendments (CLIA) in the United States, to study critical gaps in ncRNA validation studies. This review describes the leading candidate ncRNA subclasses, their biogenesis and cellular function, and identifies specific pre-analytical variables with disproportionate impact on testing performance. We summarize these findings with strategic recommendations to clinicians and biomedical scientists involved in the design, conduct, and translation of ncRNA biomarker development.

Authorized SARS-CoV-2 molecular methods show wide variability in the limit of detection

On February 29th, 2020, the U.S. Food and Drug Administration issued the first Emergency Use Authorization (EUA) for a SARS-CoV-2 assay outside of the U.S. Centers for Disease Control and Prevention. As of May 3rd, 2021, 289 total EUAs have been granted. Like influenza, there is no standard for defining limit of detection (LoD), but rather guidance that analytical sensitivity/LoD be established as the level that gives a 95% detection rate in at least 20 replicates. Here we compare the performance characteristics of SARS-CoV-2 tests receiving EUA by standardizing sensitivity to a common unit of measure and assess the variability in LoD between tests. Additionally, we looked at factors that may impact sensitivities due to lack of standardization of the test development process and compare results for a standardized reference panel for comparative analysis within a subset of EUA tests offered by the U.S. Food and Drug Administration.

Head Size in Phelan-McDermid Syndrome: A Literature Review and Pooled Analysis of 198 Patients Identifies Candidate Genes on 22q13

Phelan-McDermid syndrome (PMS) is a multisystem disorder that is associated with deletions of the 22q13 genomic region or pathogenic variants in the SHANK3 gene. Notable features include developmental issues, absent or delayed speech, neonatal hypotonia, seizures, autism or autistic traits, gastrointestinal problems, renal abnormalities, dolichocephaly, and both macro- and microcephaly. Assessment of the genetic factors that are responsible for abnormal head size in PMS has been hampered by small sample sizes as well as a lack of attention to these features. Therefore, this study was conducted to investigate the relationship between head size and genes on chromosome 22q13. A review of the literature was conducted to identify published cases of 22q13 deletions with information on head size to conduct a pooled association analysis. Across 56 studies, we identified 198 cases of PMS with defined deletion sizes and head size information. A total of 33 subjects (17%) had macrocephaly, 26 (13%) had microcephaly, and 139 (70%) were normocephalic. Individuals with macrocephaly had significantly larger genomic deletions than those with microcephaly or normocephaly (p < 0.0001). A genomic region on 22q13.31 was found to be significantly associated with macrocephaly with CELSR1, GRAMD4, and TBCD122 suggested as candidate genes. Investigation of these genes will aid the understanding of head and brain development.

Stratification of a Phelan-McDermid Syndrome Population Based on Their Response to Human Growth Hormone and Insulin-like Growth Factor

Phelan-McDermid syndrome (PMS), caused by pathogenic variants in the SHANK3 gene or 22q13 deletions, is characterized by intellectual disability, autistic features, developmental delays, and neonatal hypotonia. Insulin-like growth factor 1 (IGF-1) and human growth hormone (hGH) have been shown to reverse neurobehavioral deficits in PMS. We assessed the metabolic profiling of 48 individuals with PMS and 50 controls and determined subpopulations by taking the top and bottom 25% of responders to hGH and IGF-1. A distinct metabolic profile for individuals with PMS showed a reduced ability to metabolize major energy sources and a higher metabolism of alternative energy sources. The analysis of the metabolic response to hGH or IGF-1 highlighted a major overlap between both high and low responders, validating the model and suggesting that the two growth factors share many target pathways. When we investigated the effect of hGH and IGF-1 on the metabolism of glucose, the correlation between the high-responder subgroups showed less similarity, whereas the low-responders were still relatively similar. Classification of individuals with PMS into subgroups based on responses to a compound can allow an investigation into pathogenic mechanisms, the identification of molecular biomarkers, an exploration of in vitro responses to candidate drugs, and eventually the selection of better candidates for clinical trials.

Concomitant Calcium Channelopathies Involving CACNA1A and CACNA1F: A Case Report and Review of the Literature

Calcium channels are an integral component in maintaining cellular function. Alterations may lead to channelopathies, primarily manifested in the central nervous system. This study describes the clinical and genetic features of a unique 12-year-old boy harboring two congenital calcium channelopathies, involving the CACNA1A and CACNA1F genes, and provides an unadulterated view of the natural history of sporadic hemiplegic migraine type 1 (SHM1) due to the patient's inability to tolerate any preventative medication. The patient presents with episodes of vomiting, hemiplegia, cerebral edema, seizure, fever, transient blindness, and encephalopathy. He is nonverbal, nonambulatory, and forced to have a very limited diet due to abnormal immune responses. The SHM1 manifestations apparent in the subject are consistent with the phenotype described in the 48 patients identified as part of a systematic literature review. The ocular symptoms of CACNA1F align with the family history of the subject. The presence of multiple pathogenic variants make it difficult to identify a clear phenotype-genotype correlation in the present case. Moreover, the detailed case description and natural history along with the comprehensive review of the literature contribute to the understanding of this complex disorder and point to the need for comprehensive clinical assessments of SHM1.

Genetics providers' experiences using telehealth: A grounded theory approach

There was a paucity of research describing the perspectives and experiences of clinical genetics providers in telehealth prior to the SARS-CoV-2 pandemic. The available literature focused primarily on provider satisfaction and offered limited insight into genetics providers' work in telehealth. The purpose of this study, conducted just prior to the widespread knowledge of SARS-CoV-2 in the United States and mass transition to telehealth, was to understand the telehealth process from the vantage of genetics providers working in telehealth practice settings. This research employed grounded theory using the constant comparative method in coding and analysis of data to generate theory. Ten genetics providers were interviewed over the phone about their experiences, specifically the efficacy of telehealth work, providers' perspectives of patient outcomes, and personal fulfillment derived from telehealth patient care. Six themes emerged in the study: Making Professional Choices, Increasing Patient Access, Providing Effective Services, Understanding Telehealth Limits, Feelings about Telehealth Consultations, and Deepening Personal Fulfillment. These major themes guided the creation of the Theoretical Model of Telehealth Providers in Genetics, which depicts the connections between providers' personal fulfillment in telehealth, commitment to patient services, and the provision of telehealth to the public. This model may help others who are working on telehealth initiatives or developing telehealth programs. Findings from this study can support the current use and the growth of telehealth in genetics as a result of the SARS-CoV-2 pandemic. Future research is needed to describe the telehealth process and develop valid instruments for assessing and measuring the constructs of the Theoretical Model of Telehealth Providers in Genetics.

Sleep and Phelan-McDermid Syndrome: Lessons from the International Registry and the scientific literature

Background

Sleep is essential to maintaining a healthy life. Sleep disturbances among individuals with neurodevelopmental disorders are not well studied, affecting their early detection and treatment. Sleep disturbances in individuals with Phelan–McDermid Syndrome (PMS) are among the primary concerns reported by parents. However, little research has been aimed at addressing their concern.

Methods

The purpose of this investigation was to identify and quantify specific sleep disturbances in people with PMS by analyzing data collected by the PMS Foundation International Registry.

Results

The registry shows that 284 out of 384 (73.4%) individuals with confirmed chromosome 22q13 deletions or SHANK3 pathogenic variants have a sleep disturbance. The prevalence of sleep disturbances increases with age with 56% reporting a sleep disturbance in the 0–3 year age group and 90% reporting these disturbances in those over age 18 years old. The primary sleep disturbances were circadian rhythm sleep disorders that included difficulty falling asleep, frequent nighttime awakenings, difficulty returning to sleep after a nighttime awakening event, and hypersomnia and parasomnias including enuresis, night terrors, sleepwalking, and sleep apnea. Sleep disturbances were similarly frequent among individuals with SHANK3 pathogenic variants (84.8%) and those with deletions (71.9%), supporting the role of haploinsufficiency of SHANK3 in sleep.

Conclusion

Sleep disturbances are a common feature of PMS and should be considered in clinical evaluation and management because of the effect they have on the quality of life of the patients and their families.

TOMM40 genetic variants associated with healthy aging and longevity: a systematic review

Introduction

Healthy aging relies on mitochondrial functioning because this organelle provides energy and diminishes oxidative stress. Single nucleotide polymorphisms (SNPs) in TOMM40, a critical gene that produces the outer membrane protein TOM40 of mitochondria, have been associated with mitochondrial dysfunction and neurodegenerative processes. Yet it is not clear whether or how the mitochondria may impact human longevity. We conducted this review to ascertain which SNPs have been associated with markers of healthy aging.

Methods

Using the PRISMA methodology, we conducted a systematic review on PubMed and Embase databases to identify associations between TOMM40 SNPs and measures of longevity and healthy aging.

Results

Twenty-four articles were selected. The TOMM40 SNPs rs2075650 and rs10524523 were the two most commonly identified and studied SNPs associated with longevity. The outcomes associated with the TOMM40 SNPs were changes in BMI, brain integrity, cognitive functions, altered inflammatory network, vulnerability to vascular risk factors, and longevity.

Discussions

Our systematic review identified multiple TOMM40 SNPs potentially associated with healthy aging. Additional research can help to understand mechanisms in aging, including resilience, prevention of disease, and adaptation to the environment.

Factors related to initial treatment for adhesive capsulitis in the medicare population

BACKGROUND

Primary adhesive capsulitis (AC) is not well understood, and controversy remains about the most effective treatment approaches. Even less is known about the treatment of AC in the Medicare population. We aimed to fully characterize initial treatment for AC in terms of initial treatment utilization, timing of initial treatments and treatment combinations.

METHODS

Using United States Medicare claims from 2010-2012, we explored treatment utilization and patient characteristics associated with initial treatment for primary AC among 7,181 Medicare beneficiaries. Patients with primary AC were identified as patients seeking care for a new shoulder complaint in 2011, with the first visit related to shoulder referred to as the index date, an x-ray or MRI of the shoulder region, and two separate diagnoses of AC (ICD-9-CM codes: 726.00). The treatment period was defined as the 90 days immediately following the index shoulder visit. A multivariable logistic model was used to assess baseline patient factors associated with receiving surgery within the treatment period.

RESULTS

Ninety percent of beneficiaries with primary AC received treatment within 90 days of their index shoulder visit. Physical therapy (PT) alone (41%) and injection combined with PT (34%) were the most common treatment approaches. Similar patient profiles emerged across treatment groups, with higher proportions of racial minorities, socioeconomically disadvantaged and more frail patients favoring injections or watchful waiting. Black beneficiaries (OR = 0.37, [0.16, 0.86]) and those residing in the northeast (OR = 0.36, [0.18, 0.69]) had significantly lower odds of receiving surgery in the treatment period. Conversely, younger beneficiaries aged 66-69 years (OR = 6.75, [2.12, 21.52]) and 70-75 years (OR = 5.37, [1.67, 17.17]) and beneficiaries with type 2 diabetes had significantly higher odds of receiving surgery (OR = 1.41, [1.03, 1.92]).

CONCLUSIONS

Factors such as patient baseline health and socioeconomic characteristics appear to be important for physicians and Medicare beneficiaries making treatment decisions for primary AC.

Clinical findings from the landmark MEF2C-related disorders natural history study

Introduction

MEF2C‐related disorders are characterized by developmental and cognitive delay, limited language and walking, hypotonia, and seizures. A recent systematic review identified 117 patients with MEF2C‐related disorders across 43 studies. Despite these reports, the disorder is not easily recognized and assessments are hampered by small sample sizes. Our objective was to gather developmental and clinical information on a large number of patients.

Methods

We developed a survey based on validated instruments and subject area experts to gather information from parents of children with this condition. No personal identifiers were collected. Surveys and data were collected via REDCap and analyzed using Excel and SAS v9.4.

Results

Seventy‐three parents completed the survey, with 39.7% reporting a MEF2C variant and 54.8% reporting a deletion involving MEF2C. Limited speech (82.1%), seizures (86.3%), bruxism (87.7%), repetitive movements (94.5%), and high pain tolerance (79.5%) were some of the prominent features. Patients with MEF2C variants were similarly affected as those with deletions. Female subjects showed higher verbal abilities.

Conclusion

This is the largest natural history study to date and establishes a comprehensive review of developmental and clinical features for MEF2C‐related disorders. This data can help providers diagnose patients and form the basis for longitudinal or genotype–phenotype studies.

Phenotypic Variability in Phelan–McDermid Syndrome and Its Putative Link to Environmental Factors

Phelan–McDermid syndrome (PMS) is a multi-systemic disorder characterized by both genetic and phenotypic variability. Genetic abnormalities causing PMS span from pathogenic variants of the SHANK3 gene to chromosomal rearrangements affecting the 22q13 region and leading to the loss of up to over nine megabases. The clinical presentation of individuals with PMS includes intellectual disability, neonatal hypotonia, delayed or absent speech, developmental delay, and minor dysmorphic facial features. Several other features may present with differences in age of onset and/or severity: seizures, autism, regression, sleep disorders, gastrointestinal problems, renal disorders, dysplastic toenails, and disrupted thermoregulation. Among the causes of this phenotypic variability, the size of the 22q13 deletion has effects that may be influenced by environmental factors interacting with haploinsufficiency or hemizygous variants of certain genes. Another mechanism linking environmental factors and phenotypic variability in PMS involves the loss of one copy of genes like BRD1 or CYP2D6, located at 22q13 and involved in the regulation of genomic methylation or pharmacokinetics, which are also influenced by external agents, such as diet and drugs. Overall, several non-mutually exclusive genetic and epigenetic mechanisms interact with environmental factors and may contribute to the clinical variability observed in individuals with PMS. Characterization of such factors will help to better manage this disorder.

Genetic and metabolic profiling of individuals with Phelan-McDermid syndrome presenting with seizures

Phelan-McDermid syndrome (PMS) (OMIM*606232) is a rare genetic disorder characterized by intellectual disability, autistic features, speech delay, minor dysmorphia, and seizures. This study was conducted to investigate the prevalence of seizures and the association with genetic and metabolic features since there has been little research related to seizures in PMS. For 57 individuals, seizure data was collected from caregiver interviews, genetic data from existing cytogenetic records and Sanger sequencing for nine 22q13 genes, and metabolic profiling from the Phenotype Mammalian MicroArray (PM-M) developed by Biolog. Results showed that 46% of individuals had seizures with the most common type being absence and grand-mal seizures. Seizures were most prevalent in individuals with pathogenic SHANK3 mutations (70%), those with deletion sizes >4 Mb (16%), and those with deletion sizes <4 Mb (71%) suggesting involvement of genes in addition to SHANK3. Additionally, a 3 Mb genomic region on 22q13.31 containing the gene TBC1D22A, was found to be significantly associated with seizure prevalence. A distinct metabolic profile was identified for individuals with PMS with seizures and suggested among other features a disrupted utilization of main energy sources using Biolog plates. The results of this study will be helpful for clinicians and families in anticipating seizures in these children and for researchers to identify candidate genes for the seizure phenotype.

The epidemiology and etiology of adhesive capsulitis in the U.S. Medicare population

Background

Adhesive capsulitis (AC) of the shoulder, also known as frozen shoulder, causes substantial pain and disability. In cases of secondary AC, the inflammation and fibrosis of the synovial joint can be triggered by trauma or surgery to the joint followed by extended immobility. However, for primary AC the inciting trigger is unknown. The burden of the disorder among the elderly is also unknown leading to this age group being left out of therapeutic research studies, potentially receiving delayed diagnoses, and unknown financial costs to the Medicare system. The purpose of this analysis was to describe the epidemiology of AC in individuals over the age of 65, an age group little studied for this disorder. The second purpose was to investigate whether specific medications, co-morbidities, infections, and traumas are risk factors or triggers for primary AC in this population.

Methods

We used Medicare claims data from 2010–2012 to investigate the prevalence of AC and assess comorbid risk factors and seasonality. Selected medications, distal trauma, and classes of infections as potential inflammatory triggers for primary AC were investigated using a case–control study design with patients with rotator cuff tears as the comparison group. Medications were identified from National Drug codes and translated to World Health Organization ATC codes for analysis. Health conditions were identified using ICD9-CM codes.

Results

We found a one-year prevalence rate of AC of approximately 0.35% among adults aged 65 years and older which translates to approximately 142,000 older adults in the United States having frozen shoulder syndrome. Diabetes and Parkinson’s disease were significantly associated with the diagnosis of AC in the elderly. Cases were somewhat more common from August through December, although a clear seasonal trend was not observed. Medications, traumas, and infections were similar for cases and controls.

Conclusions

This investigation identified the burden of AC in the US elderly population and applied case–control methodology to identify triggers for its onset in this population. Efforts to reduce chronic health conditions such as diabetes may reduce seemingly unrelated conditions such as AC. The inciting trigger for this idiopathic condition remains elusive.

Tremors: A concept analysis

AIM

This article seeks to clarify and define the concept of tremors.

DESIGN

The Walker & Avant (2005) concept analysis method was followed.

METHODS

A search of PubMed, Academic Search Complete, CINAHL, ERIC, Google and Google Scholar was performed.

RESULTS

Through this process, uses of the concept were assessed including definitions and categories of tremors. Defining attributes were found to include "movement disorder," "shaking motions," "involuntary," "oscillatory," "rhythmic," "not painful or life threatening," "always present but variable" and "can sometimes be repressed." We identified two model cases and a borderline case, antecedents, consequences and empirical referents (including measurement tools) of tremors.

CONCLUSION

The concept analysis process has clarified and illuminated an operational definition of tremors: that tremors are a movement disorder characterized by shaking motions that are involuntary, oscillatory, rhythmic, non-painful, always present although vary in severity, and can be repressed by changing posture or going into a rest position.

The impact of pharmacogenetic testing in patients exposed to polypharmacy: a scoping review

Polypharmacy poses a significant risk for adverse reactions. While there are clinical decision support tools to assist clinicians in medication management, pharmacogenetic testing to identify potential drug-gene or drug-drug-gene interactions is not widely implemented in the clinical setting. A PRISMA-compliant scoping review was performed to determine if pharmacogenetic testing for absorption, distribution, metabolism, and excretion (ADME)-related genetic variants is associated with improved clinical outcomes in patients with polypharmacy. Six studies were reviewed. Five reported improved clinical outcomes, reduced side effects, reduction in the number of drugs used, or reduced healthcare utilization. The reviewed studies varied in methodological quality, risk of bias, and outcome measures. Age, diet, disease state, and treatment adherence also influence drug response, and may confound the relationship between genetic polymorphisms and treatment outcomes. Further studies using a randomized control design are needed. We conclude that pharmacogenetic testing represents an opportunity to improve health outcomes in patients exposed to polypharmacy, particularly in patients with psychiatric disorders and the elderly.

Genetic Findings as the Potential Basis of Personalized Pharmacotherapy in Phelan-McDermid Syndrome

Phelan-McDermid syndrome (PMS) is a genetic disorder often characterized by autism or autistic-like behavior. Most cases are associated with haploinsufficiency of the SHANK3 gene resulting from deletion of the gene at 22q13.3 or from a pathogenic variant in the gene. Treatment of PMS often targets SHANK3, yet deletion size varies from <50 kb to >9 Mb, potentially encompassing dozens of genes and disrupting regulatory elements altering gene expression, inferring the potential for multiple therapeutic targets. Repurposed drugs have been used in clinical trials investigating therapies for PMS: insulin-like growth factor 1 (IGF-1) for its effect on social and aberrant behaviors, intranasal insulin for improvements in cognitive and social ability, and lithium for reversing regression and stabilizing behavior. The pharmacogenomics of PMS is complicated by the CYP2D6 enzyme which metabolizes antidepressants and antipsychotics often used for treatment. The gene coding for CYP2D6 maps to 22q13.2 and is lost in individuals with deletions larger than 8 Mb. Because PMS has diverse neurological and medical symptoms, many concurrent medications may be prescribed, increasing the risk for adverse drug reactions. At present, there is no single best treatment for PMS. Approaches to therapy are necessarily complex and must target variable behavioral and physical symptoms of PMS.

Comprehensive investigation of the phenotype of MEF2C-related disorders in human patients: A systematic review

MEF2C-related disorders (aka MEF2C-haploinsufficiency) are caused by variations in or involving the MEF2C gene and are characterized by intellectual disability, developmental delay, lack of speech, limited walking, and seizures. Despite these findings, the disorder is not easily recognized clinically. We performed a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to assemble the most comprehensive list of patients and their phenotypes. Through searching PubMed, Web of Science, and MEDLINE, 43 articles met the inclusion criteria and were fully reviewed. One hundred and seventeen patients were identified from these publications with most having a phenotype of intellectual disability, developmental delay, seizures, hypotonia, absent speech, inability to walk, stereotypic movements, and MRI abnormalities. Nonclassical findings included one patient with a question mark ear, two patients with a jugular pit, one patient with a unique neuroendocrine finding, and nine patients that did not have MEF2C deletions or disruptions but may be affected due to a positional effect on MEF2C. This systematic review characterizes the phenotype of MEF2C-related disorders, documents the severity of this condition, and will help providers to better diagnose and care for patients and their families. Additionally, this compiled information provides a comprehensive resource for investigators interested in pursuing specific genotype-phenotype correlations.

DNA methylation epi-signature is associated with two molecularly and phenotypically distinct clinical subtypes of Phelan-McDermid syndrome

Background

Phelan-McDermid syndrome is characterized by a range of neurodevelopmental phenotypes with incomplete penetrance and variable expressivity. It is caused by a variable size and breakpoint microdeletions in the distal long arm of chromosome 22, referred to as 22q13.3 deletion syndrome, including the SHANK3 gene. Genetic defects in a growing number of neurodevelopmental genes have been shown to cause genome-wide disruptions in epigenomic profiles referred to as epi-signatures in affected individuals.

Results

In this study we assessed genome-wide DNA methylation profiles in a cohort of 22 individuals with Phelan-McDermid syndrome, including 11 individuals with large (2 to 5.8 Mb) 22q13.3 deletions, 10 with small deletions (< 1 Mb) or intragenic variants in SHANK3 and one mosaic case. We describe a novel genome-wide DNA methylation epi-signature in a subset of individuals with Phelan-McDermid syndrome.

Conclusion

We identified the critical region including the BRD1 gene as responsible for the Phelan-McDermid syndrome epi-signature. Metabolomic profiles of individuals with the DNA methylation epi-signature showed significantly different metabolomic profiles indicating evidence of two molecularly and phenotypically distinct clinical subtypes of Phelan-McDermid syndrome.

Intellectual functioning in alpha-mannosidosis

Alpha-mannosidosis is a rare inherited metabolic disorder (OMIM #248500) caused by mutations in the enzyme α-mannosidase encoded by the gene MAN2B1. Patients have distinct physical and developmental features, but only limited information regarding standardized cognitive functioning of patients has been published. Here we contribute intellectual ability scores (IQ) on 12 patients with alpha-mannosidosis (ages 8-59 years, 10 males, 2 females). In addition, a pooled analysis was performed with data collected from this investigation and 31 cases obtained from the literature, allowing a comprehensive analysis of intellectual functioning in this rare disease. The initial and pooled analyses show that patients with alpha-mannosidosis have variable degrees of intellectual disability but show decline in IQ with age, particularly during the first decade of life. Patients treated with hematopoietic stem cell transplantation tend to show stabilized cognitive abilities.

Functional genomics analysis of Phelan-McDermid syndrome 22q13 region during human neurodevelopment

Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder characterized by varying degrees of intellectual disability, severely delayed language development and specific facial features, and is caused by a deletion within chromosome 22q13.3. SHANK3, which is located at the terminal end of this region, has been repeatedly implicated in other neurodevelopmental disorders and deletion of this gene specifically is thought to cause much of the neurologic symptoms characteristic of PMS. However, it is still unclear to what extent SHANK3 deletions contribute to the PMS phenotype, and what other genes nearby are causal to the neurologic disease. In an effort to better understand the functional landscape of the PMS region during normal neurodevelopment, we assessed RNA-sequencing (RNA-seq) expression data collected from post-mortem brain tissue from developmentally normal subjects over the course of prenatal to adolescent age and analyzed expression changes of 65 genes on 22q13. We found that the majority of genes within this region were expressed in the brain, with ATNX10, MLC1, MAPK8IP2, and SULT4A1 having the highest overall expression. Analysis of the temporal profiles of the highest expressed genes revealed a trend towards peak expression during the early post-natal period, followed by a drop in expression later in development. Spatial analysis revealed significant region specific differences in the expression of SHANK3, MAPK8IP2, and SULT4A1. Region specific expression over time revealed a consistently unique gene expression profile within the cerebellum, providing evidence for a distinct developmental program within this region. Exon-specific expression of SHANK3 showed higher expression within exons contributing to known brain specific functional isoforms. Overall, we provide an updated roadmap of the PMS region, implicating several genes and time periods as important during neurodevelopment, with the hope that this information can help us better understand the phenotypic heterogeneity of PMS.

Cholesterol Control Among Uninsured Adults Did Not Improve From 2001-2004 to 2009-2012 as Disparities With Both Publicly and Privately Insured Adults Doubled

BACKGROUND

Low-density lipoprotein cholesterol (LDL-C) control is higher among insured than uninsured adults, but data on time trends and contributing factors are incomplete and important for improving health equity.

METHODS AND RESULTS

Awareness, treatment, and control of elevated LDL-C were compared among insured versus uninsured and publicly versus privately insured adults, aged 21 to 64 years, in National Health and Nutrition Examination Surveys from 2001 to 2004, 2005 to 2008, and 2009 to 2012 using Adult Treatment Panel-3 criteria. Compared with insured adults, uninsured adults were younger; were more often minority; reported lower incomes, less education, and fewer healthcare encounters; and had lower awareness and treatment of elevated LDL-C (P<0.0001). LDL-C control was higher among insured than uninsured adults in 2001 to 2004 (mean±SEM, 21.4±1.6% versus 10.5±2.6%; P<0.01), and the gap widened by 2009 to 2012 (35.1±1.9% versus 11.3±2.2%; P<0.0001). Despite more minorities (P<0.01), greater poverty, and less education (P<0.001), publicly insured adults had more healthcare visits/year than privately insured adults (P<0.001) and similar awareness, treatment, and control of LDL-C from 2001 to 2012. In multivariable logistic regression, significant positive predictors of cholesterol awareness, treatment, and control included more frequent health care (strongest), increasing age, private healthcare insurance versus uninsured, and hypertension. Public insurance (versus uninsured) was a significant positive predictor of LDL-C control, whereas income <200% versus ≥200% of federal poverty was a significant negative predictor.

CONCLUSIONS

LDL-C control improved similarly over time in publicly and privately insured adults but was stagnant among the uninsured. Healthcare insurance largely addresses socioeconomic barriers to effective LDL-C management, yet poverty retains an independent adverse effect.

Opportunities for improving cardiovascular health outcomes in adults younger than 65 years with guideline-recommended statin therapy

The impact of age, race/ethnicity, healthcare insurance, and selected clinical variables on statin-preventable ASCVD were quantified in adults aged 21 to 79 years from National Health and Nutrition Examination Surveys 2007-2012 using the 2013 American College of Cardiology/American Heart Association guideline on the treatment of cholesterol. Among ≈42.4 million statin-eligible, untreated adults, 52.6% were hypertensive and 71% were younger than 65 years. Of ≈232 000 statin-preventable ASCVD events annually, most occur in individuals younger than 65 years, with higher proportions in blacks and Hispanics than whites (73.0% and 69.2% vs 56.9%, respectively; P<.01). Among adults younger than 65 years, the ratio of statin-eligible but untreated to statin-treated adults was higher in blacks and Hispanics than whites (3.0 and 2.9 vs 1.3, respectively; P<.01), and blacks, men, hypertensives, and cigarette smokers were more likely to be statin eligible than their statin-ineligible counterparts by multivariable logistic regression. Two thirds of untreated statin-eligible adults had two or more healthcare visits per year. Identifying and treating more statin-eligible adults in the healthcare system could improve cardiovascular health equity.

When folic acid fails: Insights from 20 years of neural tube defect surveillance in South Carolina

Neural tube defects (NTDs) are the most common of the severe malformations of the brain and spinal cord. Increased maternal intake of folic acid (FA) during the periconceptional period is known to reduce NTD risk. Data from 1046 NTD cases in South Carolina were gathered over 20 years of surveillance. It was possible to determine maternal periconceptional FA use in 615 NTD-affected pregnancies. In 163 occurrent (26.9%) and two recurrent (22%) NTD cases, the mothers reported periconceptional FA use. These women were older and more likely to be white. Maternal periconceptional FA usage was reported in 40.4% of cases of spina bifida with other anomalies but in only 25.2% of isolated spina bifida cases (P = 0.02). This enrichment for associated anomalies was not noted among cases of anencephaly or of encephalocele. Among the 563 subsequent pregnancies to mothers with previous NTD-affected pregnancies, those taking FA had a 0.4% NTD recurrence rate, but the recurrence without FA was 8.5%. NTDs with other associated findings were less likely to be prevented by FA, suggesting there is a background NTD rate that cannot be further reduced by FA. Nonetheless, the majority (73.9%) of NTDs in pregnancies in which the mothers reported periconceptional FA use were isolated NTDs of usual types. Cases in which FA failed in prevention of NTDs provide potential areas for further study into the causation of NTDs. The measures and techniques implemented in South Carolina can serve as an effective and successful model for prevention of NTD occurrence and recurrence.

Clinical and genomic evaluation of 201 patients with Phelan-McDermid syndrome

This study is the first to describe age-related changes in a large cohort of patients with Phelan-McDermid syndrome (PMS), also known as 22q13 deletion syndrome. Over a follow-up period of up to 12 years, physical examinations and structured interviews were conducted for 201 individuals diagnosed with PMS, 120 patients had a focused, high-resolution 22q12q13 array CGH, and 92 patients' deletions were assessed for parent-of-origin. 22q13 genomic anomalies include terminal deletions of 22q13 (89 %), terminal deletions and interstitial duplications (9 %), and interstitial deletions (2 %). Considering different age groups, in older patients, behavioral problems tended to subside, developmental abilities improved, and some features such as large or fleshy hands, full or puffy eyelids, hypotonia, lax ligaments, and hyperextensible joints were less frequent. However, the proportion reporting an autism spectrum disorder, seizures, and cellulitis, or presenting with lymphedema or abnormal reflexes increased with age. Some neurologic and dysmorphic features such as speech and developmental delay and macrocephaly correlated with deletion size. Deletion sizes in more recently diagnosed patients tend to be smaller than those diagnosed a decade earlier. Seventy-three percent of de novo deletions were of paternal origin. Seizures were reported three times more often among patients with a de novo deletion of the maternal rather than paternal chromosome 22. This analysis improves the understanding of the clinical presentation and natural history of PMS and can serve as a reference for the prevalence of clinical features in the syndrome.

22q13.2q13.32 genomic regions associated with severity of speech delay, developmental delay, and physical features in Phelan-McDermid syndrome

PURPOSE

Phelan-McDermid syndrome is a developmental disability syndrome with varying deletions of 22q13 and varying clinical severity. We tested the hypothesis that, in addition to loss of the telomeric gene SHANK3, specific genomic regions within 22q13 are associated with important clinical features.

METHODS

We used a customized oligo array comparative genomic hybridization of 22q12.3-terminus to obtain deletion breakpoints in a cohort of 70 patients with terminal 22q13 deletions. We used association and receiver operating characteristic statistical methods in a novel manner and also incorporated protein interaction networks to identify 22q13 genomic locations and genes associated with clinical features.

RESULTS

Specific genomic regions and candidate genes within 22q13.2q13.32 were associated with severity of speech/language delay, neonatal hypotonia, delayed age at walking, hair-pulling behaviors, male genital anomalies, dysplastic toenails, large/fleshy hands, macrocephaly, short and tall stature, facial asymmetry, and atypical reflexes. We also found regions suggestive of a negative association with autism spectrum disorders.

CONCLUSION

This work advances the field of research beyond the observation of a correlation between deletion size and phenotype and identifies candidate 22q13 loci, and in some cases specific genes, associated with singular clinical features observed in Phelan-McDermid syndrome. Our statistical approach may be useful in genotype-phenotype analyses for other microdeletion or microduplication syndromes.

Prevalence of SHANK3 variants in patients with different subtypes of autism spectrum disorders

Autism spectrum disorders (ASDs) include three main conditions: autistic disorder (AD), pervasive developmental disorder, not otherwise specified (PDD-NOS), and Asperger syndrome. It has been shown that many genes associated with ASDs are involved in the neuroligin-neurexin interaction at the glutamate synapse: NLGN3, NLGN4, NRXN1, CNTNAP2, and SHANK3. We screened this last gene in two cohorts of ASD patients (133 patients from US and 88 from Italy). We found 5/221 (2.3%) cases with pathogenic alterations: a 106 kb deletion encompassing the SHANK3 gene, two frameshift mutations leading to premature stop codons, a missense mutation (p.Pro141Ala), and a splicing mutation (c.1820-4 G>A). Additionally, in 17 patients (7.7%) we detected a c.1304+48C>T transition affecting a methylated cytosine in a CpG island. This variant is reported as SNP rs76224556 and was found in both US and Italian controls, but it results significantly more frequent in our cases than in the control cohorts. The variant is also significantly more common among PDD-NOS cases than in AD cases. We also screened this gene in an independent replication cohort of 104 US patients with ASDs, in which we found a missense mutation (p.Ala1468Ser) in 1 patient (0.9%), and in 8 patients (7.7%) we detected the c.1304+48C>T transition. While SHANK3 variants are present in any ASD subtype, the SNP rs76224556 appears to be significantly associated with PDD-NOS cases. This represents the first evidence of a genotype-phenotype correlation in ASDs and highlights the importance of a detailed clinical-neuropsychiatric evaluation for the effective genetic screening of ASD patients.

Association between deletion size and important phenotypes expands the genomic region of interest in Phelan-McDermid syndrome (22q13 deletion syndrome)

BACKGROUND

The clinical features of Phelan-McDermid syndrome (also known as 22q13 deletion syndrome) are highly variable and include hypotonia, speech and other developmental delays, autistic traits and mildly dysmorphic features. Patient deletion sizes are also highly variable, prompting this genotype-phenotype association study.

METHODS

Terminal deletion breakpoints were identified for 71 individuals in a patient cohort using a custom-designed high-resolution oligonucleotide array comparative genomic hybridisation platform with a resolution of 100 bp.

RESULTS

Patient deletion sizes were highly variable, ranging from 0.22 to 9.22 Mb, and no common breakpoint was observed. SHANK3, the major candidate gene for the neurologic features of the syndrome, was deleted in all cases. Sixteen features (neonatal hypotonia, neonatal hyporeflexia, neonatal feeding problems, speech/language delay, delayed age at crawling, delayed age at walking, severity of developmental delay, male genital anomalies, dysplastic toenails, large or fleshy hands, macrocephaly, tall stature, facial asymmetry, full brow, atypical reflexes and dolichocephaly) were found to be significantly associated with larger deletion sizes, suggesting the role of additional genes or regulatory regions proximal to SHANK3. Individuals with autism spectrum disorders (ASDs) were found to have smaller deletion sizes (median deletion size of 3.39 Mb) than those without ASDs (median deletion size 6.03 Mb, p=0.0144). This may reflect the difficulty in diagnosing ASDs in individuals with severe developmental delay.

CONCLUSIONS

This genotype-phenotype analysis explains some of the phenotypic variability in the syndrome and identifies new genomic regions with a high likelihood for causing important developmental phenotypes such as speech delay.

Effect of population stratification on the identification of significant single-nucleotide polymorphisms in genome-wide association studies

The North American Rheumatoid Arthritis Consortium case-control study collected case participants across the United States and control participants from New York. More than 500,000 single-nucleotide polymorphisms (SNPs) were genotyped in the sample of 2000 cases and controls. Careful adjustment for the confounding effect of population stratification must be conducted when analyzing these data; the variance inflation factor (VIF) without adjustment is 1.44. In the primary analyses of these data, a clustering algorithm in the program PLINK was used to reduce the VIF to 1.14, after which genomic control was used to control residual confounding. Here we use stratification scores to achieve a unified and coherent control for confounding. We used the first 10 principal components, calculated genome-wide using a set of 81,500 loci that had been selected to have low pair-wise linkage disequilibrium, as risk factors in a logistic model to calculate the stratification score. We then divided the data into five strata based on quantiles of the stratification score. The VIF of these stratified data is 1.04, indicating substantial control of stratification. However, after control for stratification, we find that there are no significant loci associated with rheumatoid arthritis outside of the HLA region. In particular, we find no evidence for association of TRAF1-C5 with rheumatoid arthritis.

Confirming the Utility of Four Kidney Biomarker Tests in a Longitudinal Follow-Up Study

In this follow-up study, 526 persons were followed for almost 5 years to assess the reversibility and predictive value of four kidney biomarkers in a field epidemiology setting. This study examined (a) whether elevations in urinary albumin, N-acetyl-beta-D-glucosaminidase, retinol-binding protein, and alanine aminopeptidase remained elevated at follow-up and (b) whether these initial elevations were predictive of kidney disease (as measured by markers of kidney dysfunction: serum creatinine, serum cystatin C, creatinine clearance, and urine osmolality) at follow-up. Study participants were 8-76 years of age at baseline and were followed for an average of 4.5 years. Approximately 50% of adults who had an elevated biomarker did not have an elevation at followup. Youths with elevated biomarkers at baseline, but who completed adolescence by the time of the follow-up, no longer had any elevations in biomarkers at follow-up. Adult participants who had elevated biomarkers and selected health conditions at baseline (diabetes and, to a lesser extent, heart disease, hypertension, gout, and urinary tract disease) were more likely to show early indicators of kidney impairment at follow-up. Participants with these health conditions and normal kidney biomarker values at baseline had kidney test results at follow-up that were similar to results of study participants who did not have these health conditions at baseline. The presence or absence of elevated biomarkers at baseline among generally healthy participants was not associated with the development of early indicators of kidney impairment at follow-up. This longitudinal study confirmed the utility of these four kidney biomarker tests as markers of preclinical organ dysfunction among adults with certain preexisting medical conditions.

Influence of environmental zinc on the association between environmental and biological measures of lead in children

Exposure to lead, a common environmental contaminant found at hazardous waste sites, has been associated with adverse health effects to humans. Zinc, a nutritionally essential metal, may influence both the absorption and the toxicity of lead. The purpose of this study was to determine if zinc levels present in the environment affect the association between environmental lead measured in two small communities in the northeastern United States and biological measurements of lead in the residents of these communities. Soil and dust sampled in and around the homes of all participants were tested for lead and zinc. Residents aged 6 months to 14 years (n=214) provided blood samples for the determination of blood lead concentrations. Soil and dust measurements of environmental lead were positively associated with blood lead, regardless of the corresponding zinc levels in these samples. However, the magnitude of this association was 20% to 46% lower in areas with high environmental measures of zinc. The interactions between environmental lead and environmental zinc levels and blood lead concentrations suggest that zinc may influence the association between soil and dust lead and corresponding blood lead levels.

Effects of exposure to low levels of environmental cadmium on renal biomarkers

We conducted a study among residents of a small community contaminated with heavy metals from a defunct zinc smelter and residents from a comparison community to determine whether biologic measures of cadmium exposure were associated with biomarkers of early kidney damage. Creatinine-adjusted urinary cadmium levels did not differ between the smelter and comparison communities; thus we combined individuals from both communities (n = 361) for further analyses. The overall mean urinary cadmium level was low, 0.26 microg/g creatinine, similar to reference values observed in the U.S. general population. For children ages 6-17 years, urinary concentration of N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), and albumin were positively associated with urinary cadmium, but these associations did not remain statistically significant after adjusting for urinary creatinine and other potential confounders. For adults ages 18 or older, urinary concentration of NAG, AAP, and albumin were positively associated with urinary cadmium. The associations with NAG and AAP but not with albumin remained statistically significant after adjusting for creatinine and other potential confounders. We found a positive dose-effect relationship between levels of creatinine-adjusted urinary cadmium and NAG and AAP activity, and statistically significant differences in mean activity for these two enzymes between the highest (> or =1.0 microg cadmium/g creatinine) and the lowest (< or =0.25 microg cadmium/g creatinine) exposure groups. The findings of this study indicate that biologic measures of cadmium exposure at levels below 2.0 microg/g creatinine may produce measurable changes in kidney biomarkers.

Serum immunoglobulins and lymphocyte subset distributions in children and adults living in communities assessed for lead and cadmium exposure

This study assessed the impact of environmental cadmium and lead exposure on the immune system of more than 2000 children and adults. Serum immunoglobulins [immunoglobulins (Ig) A, G, and M] and peripheral blood lymphocyte phenotypes (T cells, B cells, NK cells, and CD4/CD8 subsets) were measured in a total of 2041 children and adults who lived either in sites with elevated soil levels of cadmium and lead (n = 1561) or in comparison communities (n = 480). The blood lead and urine cadmium levels of participants were somewhat higher than national averages. Mean blood lead levels were 7 microg/dl for participants aged 6-35 mo; 6 microg/dl for participants aged 36-71 mo, 4 microg/dl for participants aged 6-15 yr; and 4.3 microg/dl for participants aged 16-75 yr. Multivariate analysis indicated no marked differences in any of the immune marker distributions attributed to lead for adults or children over 3 yr of age. However, in children under age 3, increased blood lead levels, principally those over 15 microg/dl, were associated with increases in IgA, IgG, IgM, and circulating B lymphocytes. Among adults, urine cadmium levels over 1.5 microg/g were associated with higher levels of IgA and circulating B lymphocytes. No evidence of immunosuppression was noted. The findings of potential immunologic effects at lead levels > 15 microg/dl in young children and at urine cadmium levels > 1.5 microg/g in adults are interesting, but too few participants had these high levels to delineate a threshold. Therefore, we find these results intriguing, but requiring confirmation in populations with higher exposure levels.