Global developmental delay and a de novo deletion of the 16p13.13 region

Many rare genetic variants are associated with the risk of atypical neurodevelopmental trajectories. In this study, we report a patient with developmental delay, autistic traits and multiple congenital anomalies, including congenital heart anomalies and orofacial cleft, with a 0.832 Mb de novo deletion of the 16p13.13 region classified as a variant of uncertain significance. Comparison of similar sized deletions and duplications overlapping the same genes in the DECIPHER database, revealed seven reports of copy number variants (CNVs), four duplications and three deletions. A neurodevelopmental phenotype including learning disability and intellectual disability was noted in some of the DECIPHER entries where phenotype was provided. Although the association between a deletion in this region and an atypical neurodevelopmental trajectory remains to be elucidated, the overlapping CNVs with neurodevelopmental phenotypes suggests possible candidate genes within the 16p13.13 region.

The Phenotypic variability of 16p11.2 distal BP2-BP3 deletion in a transgenerational family and in neurodevelopmentally ascertained samples

BACKGROUND

We present genomic and phenotypic findings of a transgenerational family consisting of three male offspring, each with a maternally inherited distal 220 kb deletion at locus 16p11.2 (BP2-BP3). Genomic analysis of all family members was prompted by a diagnosis of autism spectrum disorder (ASD) in the eldest child, who also presented with a low body mass index.

METHODS

All male offspring underwent extensive neuropsychiatric evaluation. Both parents were also assessed for social functioning and cognition. The family underwent whole-genome sequencing. Further data curation was undertaken from samples ascertained for neurodevelopmental disorders and congenital abnormalities.

RESULTS

On medical examination, both the second and third-born male offspring presented with obesity. The second-born male offspring met research diagnostic criteria for ASD at 8 years of age and presented with mild attention deficits. The third-born male offspring was only noted as having motor deficits and received a diagnosis of developmental coordination disorder. Other than the 16p11.2 distal deletion, no additional contributing variants of clinical significance were observed. The mother was clinically evaluated and noted as having a broader autism phenotype.

CONCLUSION

In this family, the phenotypes observed are most likely caused by the 16p11.2 distal deletion. The lack of other overt pathogenic mutations identified by genomic sequencing reinforces the variable expressivity that should be heeded in a clinical setting. Importantly, distal 16p11.2 deletions can present with a highly variable phenotype even within a single family. Our additional data curation provides further evidence on the variable clinical presentation among those with pathogenetic 16p11.2 (BP2-BP3) mutations.

Support to caregivers who have received genetic information about neurodevelopmental and psychiatric vulnerability in their young children: A narrative review

Diagnosis of pathogenic genetic variants associated with neurodevelopmental and psychiatric disorders (NPDs) is increasingly made early in life. This narrative review focuses on the need for, and provision of, psychological supports following genetic diagnosis. We conducted a literature search of publications on how caregivers are informed about the NPD vulnerability associated with genetic variants, challenges and unmet needs when receiving this information, and whether psychological supports are provided. Given its early recognition, the 22q11.2 deletion has been studied thoroughly for two decades, providing generalizable insights. This literature indicates the complex caregivers' needs related to learning about potential NPD vulnerabilities associated with a genetic variant, include how to communicate the diagnosis, how to identify early signs of NPDs, how to deal with stigma and a lack of medical expertise outside of specialized genetics clinics. With one exception, no publications describe psychotherapeutic support provided to parents. In the absence of support, caregivers struggle with several unmet needs regarding potential longer-term NPD implications of a genetic diagnosis. The field needs to go beyond explaining genetic diagnoses and associated vulnerabilities, and develop approaches to support caregivers with communicating and managing NPD implications across the child's lifespan.

Abstract 1785: Multi-step engineering of gene-edited CAR T cells using RNA lipid nanoparticles

Autologous chimeric antigen receptor (CAR) T therapies utilize patient cells and can be limited by cell quality, and the high manufacturing burden of viral vectors. As such, there is a need for allogeneic, “off-the-shelf” CAR T cells to make these transformative treatments widely available. However, allogeneic therapies require multiple genetic engineering steps to express CAR and to delete proteins responsible for graft-versus-host disease. Messenger RNA (mRNA) is a promising approach for expression of therapeutic proteins and gene editing nucleases. In this work, we demonstrate a new method for multi-step engineering of gene-edited CAR T cells using RNA lipid nanoparticles (LNPs).

LNPs encapsulating Spy-Cas9 mRNA, TCR and CD52 guide RNA (sgRNA), and CAR mRNA were produced using microfluidics. The CAR construct contained an anti-CD19 scFv binding domain and CD3ζ/4-1BB co-stimulatory domains. Microgram quantities of RNA LNPs were produced to optimize LNP packaging, cargo ratios, and sgRNA combinations. Lead candidates were scaled to milligrams. Purified human primary T cells were cultured, activated, and expanded in serum-free media in plates, flasks and bioreactors. CAR+, TCR− or CD52− cells were generated by addition of the corresponding LNP to activated cells. Cytotoxic killing was determined by co-culture assays with leukemia cells. Gene knockout, CAR expression, viability and cell killing were measured using flow-cytometry.

CD19 CAR was selected as a relevant protein for expression, with TCR and CD52 proteins as gene knockout targets. Single-step addition of CAR LNPs to T cells resulted in transfection efficiencies of 95.0 ± 2.1% and high protein expression. Upon TCR or CD52 LNP addition to T cells, the onset of gene editing was within 48 hours, reaching single target knockout efficiencies of 92.3 ± 3.0% (TCR−), and double knockouts (TCR−/CD52−) of 74.5 ± 6.1%. Similar results were obtained when comparing different LNP batch sizes (microgram to milligram RNA) and cell culture vessels (125,000 to 45 million cells), demonstrating scalability of both the LNP production and cell treatment. Cell viabilities above 90% were maintained at all steps and for all RNA LNPs. Finally, as proof-of-concept for multi-step engineering, sequential addition of TCR LNPs and CAR LNPs resulted in simultaneous CAR expression and TCR gene knockout. These “off-the-shelf” gene-edited CAR T cells were functionally equivalent to non-edited cells in a B cell killing assay, efficiently clearing over 80% of leukemia target cells at a 1:1 ratio.

Our findings demonstrate the advantages of LNPs for RNA delivery to T cells. The simple and gentle nature of LNP cell treatment allows for multiple genetic engineering steps for simultaneous expression and deletion of proteins. Furthermore, LNPs can be easily manufactured using microfluidics, enabling small-scale screening of RNA libraries and rapid scale-up of lead candidates for clinical translation.

Citation Format: Samuel Clarke, R Geczy, A Balgi, S Park, R Zhao, M Swaminathan, R Tieu, N Hoang, C Webb, E Watt, M Wong, M Fujisawa, N Jain, Angela Zhang, Anitha Thomas. Multi-step engineering of gene-edited CAR T cells using RNA lipid nanoparticles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1785.

Genomic architecture of autism from comprehensive whole-genome sequence annotation

Fully understanding autism spectrum disorder (ASD) genetics requires whole-genome sequencing (WGS). We present the latest release of the Autism Speaks MSSNG resource, which includes WGS data from 5,100 individuals with ASD and 6,212 non-ASD parents and siblings (total n = 11,312). Examining a wide variety of genetic variants in MSSNG and the Simons Simplex Collection (SSC; n = 9,205), we identified ASD-associated rare variants in 718/5,100 individuals with ASD from MSSNG (14.1%) and 350/2,419 from SSC (14.5%). Considering genomic architecture, 52% were nuclear sequence-level variants, 46% were nuclear structural variants (including copy-number variants, inversions, large insertions, uniparental isodisomies, and tandem repeat expansions), and 2% were mitochondrial variants. Our study provides a guidebook for exploring genotype-phenotype correlations in families who carry ASD-associated rare variants and serves as an entry point to the expanded studies required to dissect the etiology in the ∼85% of the ASD population that remain idiopathic.

Developmental implications of genetic testing for physical indications

In children undergoing genetic testing for physical health concerns, we examined how often the results also revealed information about their risk for neurodevelopmental disorders. The study sample consisted of 3056 genetic tests (1686 chromosomal microarrays--CMAs, and 1378 next-generation sequencing--NGS panels) ordered at a tertiary pediatric hospital because of a physical/congenital health problem. Tests ordered to investigate developmental concerns were excluded. Pathogenic, or likely pathogenic variants were manually reviewed for diagnostic likelihood, and for evidence of an association with a neurodevelopmental disorder (e.g., autism or intellectual disability). A total of 169 CMAs (10%) and 232 NGS panels (17%) had likely diagnostic results. More than half (52%) of all diagnostic results had established evidence of a neurodevelopmental disorder association. In summary, there is a high prevalence of neurodevelopmental implications from genetic tests ordered for physical/congenital indications. This broad clinical utility suggests a growing need for genetics-first developmental care pathways.

Neurodevelopmental functioning in probands and non-proband carriers of 22q11.2 microduplication

Microduplication of the LCR22-A to LCR22-D region on chromosome 22q11.2 is a recurrent copy number variant found in clinical populations undergoing chromosomal microarray, and at lower frequency in controls. Often inherited, there is limited data on intellectual (IQ) and psychological functioning, particularly in those individuals ascertained through a family member rather than because of neurodevelopmental disorders. To investigate the range of cognitive-behavioral phenotypes associated with 22q11.2 duplication, we studied both probands and their non-proband carrier relatives. Twenty-two individuals with 22q11.2 duplication (10 probands, 12 non-proband carriers) were prospectively assessed with a battery of neuropsychological tests, physical examination, and medical record review. Assessment measures with standardized norms included IQ, academic, adaptive, psychiatric, behavioral, and social functioning. IQ and academic skills were within the average range, with a trend toward lower scores in probands versus non-probands. Adaptive skills were within age expectations. Prevalence of attention deficits (probands only) and anxiety (both groups) was high compared with norms. The prevalence of autism spectrum disorder was relatively low (5% of total sample). Assessment of both probands and non-probands with 22q11.2 duplication suggests that the phenotypic spectrum with respect to neurodevelopment overlaps significantly with the general population. IQ and academic abilities are in the average range for most of the individuals with 22q11.2 duplication in our study, regardless of ascertainment as a proband or non-proband relative. Symptoms of attention deficit and anxiety were identified, which require further study. Results of this study further clarify the phenotype of individuals with 22q11.2 duplication, and provides important information for genetic counseling regarding this recurrent copy number variant.

Sleep phenotype of individuals with autism spectrum disorder bearing mutations in the PER2 circadian rhythm gene

The Per family of genes functions as a primary circadian rhythm maintenance in the brain. Mutations in PER2 are associated with familial advanced sleep-phase syndrome 1 (FASPS1), and recently suggested in delayed sleep phase syndrome and idiopathic hypersomnia. The detection of PER2 variants in individuals with autism spectrum disorder (ASD) and without reported sleep disorders, has suggested a role of circadian-relevant genes in the pathophysiology of ASD. It remains unclear whether these individuals may have, in addition to ASD, an undiagnosed circadian rhythm sleep disorder. The MSSNG database was used to screen whole genome sequencing data of 5,102 individuals with ASD for putative mutations in PER2. Families identified were invited to complete sleep phenotyping consisting of a structured interview and two standardized sleep questionnaires: the Pittsburgh Sleep Quality Index and the Morningness-Eveningness Questionnaire. From 5,102 individuals with ASD, two nonsense, one frameshift, and one de novo missense PER2 variants were identified (0.08%). Of these four, none had a diagnosed sleep disorder. Three reported either a history of, or ongoing sleep disturbances, and one had symptoms highly suggestive of FASPS1 (as did a mutation carrier father without ASD). The individual with the missense variant did not report sleep concerns. The ASD and cognitive profiles of these individuals varied in severity and symptoms. The results support a possible role of PER2-related circadian rhythm disturbances in the dysregulation of sleep overall and sometimes FASPS1. The relationship between dysregulated sleep and the pathophysiology of ASD require further exploration.

Genome-wide detection of tandem DNA repeats that are expanded in autism

Tandem DNA repeats vary in the size and sequence of each unit (motif). When expanded, these tandem DNA repeats have been associated with more than 40 monogenic disorders1. Their involvement in disorders with complex genetics is largely unknown, as is the extent of their heterogeneity. Here we investigated the genome-wide characteristics of tandem repeats that had motifs with a length of 2-20 base pairs in 17,231 genomes of families containing individuals with autism spectrum disorder (ASD)2,3 and population control individuals4. We found extensive polymorphism in the size and sequence of motifs. Many of the tandem repeat loci that we detected correlated with cytogenetic fragile sites. At 2,588 loci, gene-associated expansions of tandem repeats that were rare among population control individuals were significantly more prevalent among individuals with ASD than their siblings without ASD, particularly in exons and near splice junctions, and in genes related to the development of the nervous system and cardiovascular system or muscle. Rare tandem repeat expansions had a prevalence of 23.3% in children with ASD compared with 20.7% in children without ASD, which suggests that tandem repeat expansions make a collective contribution to the risk of ASD of 2.6%. These rare tandem repeat expansions included previously undescribed ASD-linked expansions in DMPK and FXN, which are associated with neuromuscular conditions, and in previously unknown loci such as FGF14 and CACNB1. Rare tandem repeat expansions were associated with lower IQ and adaptive ability. Our results show that tandem DNA repeat expansions contribute strongly to the genetic aetiology and phenotypic complexity of ASD.

A large data resource of genomic copy number variation across neurodevelopmental disorders

Copy number variations (CNVs) are implicated across many neurodevelopmental disorders (NDDs) and contribute to their shared genetic etiology. Multiple studies have attempted to identify shared etiology among NDDs, but this is the first genome-wide CNV analysis across autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia (SCZ), and obsessive-compulsive disorder (OCD) at once. Using microarray (Affymetrix CytoScan HD), we genotyped 2,691 subjects diagnosed with an NDD (204 SCZ, 1,838 ASD, 427 ADHD and 222 OCD) and 1,769 family members, mainly parents. We identified rare CNVs, defined as those found in <0.1% of 10,851 population control samples. We found clinically relevant CNVs (broadly defined) in 284 (10.5%) of total subjects, including 22 (10.8%) among subjects with SCZ, 209 (11.4%) with ASD, 40 (9.4%) with ADHD, and 13 (5.6%) with OCD. Among all NDD subjects, we identified 17 (0.63%) with aneuploidies and 115 (4.3%) with known genomic disorder variants. We searched further for genes impacted by different CNVs in multiple disorders. Examples of NDD-associated genes linked across more than one disorder (listed in order of occurrence frequency) are NRXN1, SEH1L, LDLRAD4, GNAL, GNG13, MKRN1, DCTN2, KNDC1, PCMTD2, KIF5A, SYNM, and long non-coding RNAs: AK127244 and PTCHD1-AS. We demonstrated that CNVs impacting the same genes could potentially contribute to the etiology of multiple NDDs. The CNVs identified will serve as a useful resource for both research and diagnostic laboratories for prioritization of variants.

Meta-analysis and multidisciplinary consensus statement: exome sequencing is a first-tier clinical diagnostic test for individuals with neurodevelopmental disorders

Purpose

For neurodevelopmental disorders (NDDs), etiological evaluation can be a diagnostic odyssey involving numerous genetic tests, underscoring the need to develop a streamlined algorithm maximizing molecular diagnostic yield for this clinical indication. Our objective was to compare the yield of exome sequencing (ES) with that of chromosomal microarray (CMA), the current first-tier test for NDDs.

Methods

We performed a PubMed scoping review and meta-analysis investigating the diagnostic yield of ES for NDDs as the basis of a consensus development conference. We defined NDD as global developmental delay, intellectual disability, and/or autism spectrum disorder. The consensus development conference included input from genetics professionals, pediatric neurologists, and developmental behavioral pediatricians.

Results

After applying strict inclusion/exclusion criteria, we identified 30 articles with data on molecular diagnostic yield in individuals with isolated NDD, or NDD plus associated conditions (such as Rett-like features). Yield of ES was 36% overall, 31% for isolated NDD, and 53% for the NDD plus associated conditions. ES yield for NDDs is markedly greater than previous studies of CMA (15–20%).

Conclusion

Our review demonstrates that ES consistently outperforms CMA for evaluation of unexplained NDDs. We propose a diagnostic algorithm placing ES at the beginning of the evaluation of unexplained NDDs.

Expanding the neurodevelopmental phenotypes of individuals with de novo KMT2A variants

De novo loss-of-function (LoF) variants in the KMT2A gene are associated with Wiedemann-Steiner Syndrome (WSS). Recently, de novo KMT2A variants have been identified in sequencing studies of cohorts of individuals with neurodevelopmental disorders (NDDs). However, most of these studies lack the detailed clinical information required to determine whether those individuals have isolated NDDs or WSS (i.e. syndromic NDDs). We performed thorough clinical and neurodevelopmental phenotyping on six individuals with de novo KMT2A variants. From these data, we found that all six patients met clinical criteria for WSS and we further define the neurodevelopmental phenotypes associated with KMT2A variants and WSS. In particular, we identified a subtype of Autism Spectrum Disorder (ASD) in five individuals, characterized by marked rigid, repetitive and inflexible behaviours, emotional dysregulation, externalizing behaviours, but relative social motivation. To further explore the clinical spectrum associated with KMT2A variants, we also conducted a meta-analysis of individuals with KMT2A variants reported in the published literature. We found that de novo LoF or missense variants in KMT2A were significantly more prevalent than predicted by a previously established statistical model of de novo mutation rate for KMT2A. Our genotype-phenotype findings better define the clinical spectrum associated with KMT2A variants and suggest that individuals with de novo LoF and missense variants likely have a clinically unrecognized diagnosis of WSS, rather than isolated NDD or ASD alone. This highlights the importance of a clinical genetic and neurodevelopmental assessment for individuals with such variants in KMT2A.

Communicating complex genomic information: A counselling approach derived from research experience with Autism Spectrum Disorder

Individuals with Autism Spectrum Disorder (ASD) share characteristics (impairments in socialization and communication, and repetitive interests and behaviour), but differ in their developmental course, pattern of symptoms, and cognitive and language abilities. The development of standardized phenotyping has revealed ASD to clinically be vastly heterogeneous, ranging from milder presentations to more severe forms associated with profound intellectual disability. Some 100 genes have now been implicated in the etiology of ASD, and advances in genome-wide testing continue to yield new data at an unprecedented rate. As the translation of this data is incorporated into clinical care, genetic professionals/counsellors, as well as other health care providers, will benefit from guidelines and tools to effectively communicate such genomic information. Here, we present a model to facilitate communication regarding the complexities of ASD, where clinical and genetic heterogeneity, as well as overlapping neurological conditions are inherent. We outline an approach for counselling families about their genomic results grounded in our direct experience from counselling families participating in an ASD research study, and supported by rationale from the literature.

Atypical autism in a boy with double duplication of 22q11.2: implications of increasing dosage

Duplication of chromosome 22q11.2 (LCR A-D) has been reported at higher frequencies in clinical samples than the general population, but phenotypes vary widely. Triplication (4 copies) is rare, but studying the associated phenotype may provide insight into dosage-sensitivity of the genes in this chromosomal interval. We describe a proband with a triplication, specifically a “double duplication” (two copies per chromosome) of the 22q11.2 region, while his parents and two siblings each have a single duplication (3 copies). The proband had a heart malformation, dysmorphic features, and learning and socialization deficits, whereas the other family members did not. This family illustrates that while duplication of the 22q11.2 may not be sufficient to cause clinically significant neurodevelopmental or health-related phenotypes, triplication of the same region may result in a phenotype characterized by a mild neurodevelopmental disorder, facial dysmorphism, and possibly cardiac anomalies.

Mutations in RAB39B in individuals with intellectual disability, autism spectrum disorder, and macrocephaly

Background

Autism spectrum disorder (ASD), a developmental disorder of early childhood onset, affects males four times more frequently than females, suggesting a role for the sex chromosomes. In this study, we describe a family with ASD in which a predicted pathogenic nonsense mutation in the X-chromosome gene RAB39B segregates with ASD phenotype.

Methods

Clinical phenotyping, microarray, and whole genome sequencing (WGS) were performed on the five members of this family. Maternal and female sibling X inactivation ratio was calculated, and phase was investigated. Mutant-induced pluripotent stem cells engineered for an exon 2 nonsense mutation were generated and differentiated into cortical neurons for expression and pathway analyses.

Results

Two males with an inherited RAB39B mutation both presented with macrocephaly, intellectual disability (ID), and ASD. Their female sibling with the same mutation presented with ID and a broad autism phenotype. In contrast, their transmitting mother has no neurodevelopmental diagnosis. Our investigation of phase indicated maternal preferential inactivation of the mutated allele, with no such bias observed in the female sibling. We offer the explanation that this bias in X inactivation may explain the absence of a neurocognitive phenotype in the mother. Our cellular knockout model of RAB39B revealed an impact on expression in differentiated neurons for several genes implicated in brain development and function, supported by our pathway enrichment analysis.

Conclusions

Penetrance for ASD is high among males but more variable among females with RAB39B mutations. A critical role for this gene in brain development and function is demonstrated.

Variable phenotype expression in a family segregating microdeletions of the NRXN1 and MBD5 autism spectrum disorder susceptibility genes

Autism spectrum disorder is a developmental condition of early childhood onset, which impacts socio-communicative functioning and is principally genetic in etiology. Currently, more than 50 genomic loci are deemed to be associated with susceptibility to autism spectrum disorder, showing de novo and inherited unbalanced copy number variants and smaller insertions and deletions (indels), more complex structural variants, as well as single-nucleotide variants deemed of pathological significance. However, the phenotypes associated with many of these genes are variable, and penetrance is largely unelaborated in clinical descriptions. This case report describes a family harboring two copy number variant microdeletions, which affect regions of NRXN1 and MBD5—each well-established in association with risk of autism spectrum disorder and other neurodevelopmental disorders. Although each copy number variant would likely be categorized as pathologically significant, both genomic alterations are transmitted in this family from an unaffected father to the proband, and shared by an unaffected sibling. This family case illustrates the importance of recognizing that phenotype can vary among exon overlapping variants of the same gene, and the need to evaluate penetrance of such variants in order to properly inform on risks.

Does personal genome testing drive service utilization in an adult preventive medicine clinic?

Personal genome testing (PGT) that assesses risk for common diseases may influence the use of preventive health services, but outcome data are limited. We aimed to assess health service utilization following PGT. We conducted a retrospective matched cohort study at an adult health clinic. Medical records of clients who pursued PGT at their comprehensive health assessment (CHA) over a 1-year period (N = 388) were reviewed and compared to age- and sex-matched clients who underwent CHA but not PGT (N = 388). We measured condition-specific health services used post CHA up to two subsequent visits while accounting for confounding factors (e.g., family history, health status, and age). A relatively equal number of post CHA services were used by clients who pursued PGT and those who did not pursue PGT (52% and 48%, respectively). Overall and across the majority of conditions examined, clients' service utilization was significantly associated with health status, e.g., clients identified as "at risk" on CHA for heart attack used 2.86 times more services than clients not at risk. Pursuing PGT was not significantly associated with increased use of services post CHA overall or for most of the conditions examined. Our data demonstrate that health status rather than pursuing PGT is the strongest driver of service utilization in this population. Overall, pursuit of PGT and PGT results does not appear to significantly drive the utilization of downstream health services.

Whole genome sequencing resource identifies 18 new candidate genes for autism spectrum disorder

We are performing whole-genome sequencing of families with autism spectrum disorder (ASD) to build a resource (MSSNG) for subcategorizing the phenotypes and underlying genetic factors involved. Here we report sequencing of 5,205 samples from families with ASD, accompanied by clinical information, creating a database accessible on a cloud platform and through a controlled-access internet portal. We found an average of 73.8 de novo single nucleotide variants and 12.6 de novo insertions and deletions or copy number variations per ASD subject. We identified 18 new candidate ASD-risk genes and found that participants bearing mutations in susceptibility genes had significantly lower adaptive ability (P = 6 × 10^-4). In 294 of 2,620 (11.2%) of ASD cases, a molecular basis could be determined and 7.2% of these carried copy number variations and/or chromosomal abnormalities, emphasizing the importance of detecting all forms of genetic variation as diagnostic and therapeutic targets in ASD.

Capturing the clinical utility of genomic testing: medical recommendations following pediatric microarray

Interpretation of pediatric chromosome microarray (CMA) results presents diagnostic and medical management challenges. Understanding management practices triggered by CMA will inform clinical utility and resource planning. Using a retrospective cohort design, we extracted clinical and management-related data from the records of 752 children with congenital anomalies and/or developmental delay who underwent CMA in an academic pediatric genetics clinic (2009–2011). Frequency distributions and relative rates (RR) of post-CMA medical recommendations in children with reportable and benign CMA results were calculated. Medical recommendations were provided for 79.6% of children with reportable results and 62.0% of children with benign results. Overall, recommendations included specialist consultation (40.8%), imaging (32.5%), laboratory investigations (17.2%), surveillance (4.6%), and family investigations (4.9%). Clinically significant variants and variants of uncertain clinical significance were associated with higher and slightly higher rates of management recommendations, respectively, compared with benign/no variants (RR=1.34; 95% CI (1.22–1.47); RR=1.23; 95% CI (1.09–1.38)). Recommendation rates for clinically significant versus uncertain results depended upon how uncertainty was classified (RR_broad=1.09; 95% CI (0.99–1.2); RR_narrow=1.12; 95% CI (1.02–1.24)). Recommendation rates also varied by the child's age and provider type. In conclusion, medical recommendations follow CMA for the majority of children. Compared with benign CMA results, clinically significant CMA variants are a significant driver of pediatric medical recommendations. Variants of uncertain clinical significance drive recommendations, but to a lesser extent. As a broadening range of specialists will need to respond to CMA results, targeted capacity building is warranted.

Clinical Efficacy and Effects of Xylitol Wipes on Bacterial Virulence

The aim of the study was to investigate whether xylitol-wipe use in young children prevented caries by affecting bacterial virulence. In a double-blinded randomized controlled clinical trial, 44 mother-child pairs were randomized to xylitol-wipe or placebo-wipe groups. Salivary mutans streptococci levels were enumerated at baseline, 6 months, and one year. Ten mutans streptococci colonies were isolated and genotyped from each saliva sample. Genotype-colonization stability, xylitol sensitivity, and biofilm formation of these isolates were studied. Despite a significant reduction in new caries at one year in the xylitol-wipe group, no significant differences were found between the two groups in levels of mutans streptococci. Children in the xylitol-wipe group had significantly fewer retained genotypes (p = 0.06) and more transient genotypes of mutans streptococci (p = 0.05) than those in the placebo-wipe group. At one year, there was no significant difference in the prevalence of xylitol-resistant genotypes or in biofilm formation ability of mutans streptococci isolates between the two groups. The mechanism of the caries-preventive effect of xylitol-wipe use may be related to the stability of mutans streptococci colonization. Further studies with genomic characterization methods are needed to determine specific gene(s) that account for the caries-preventive effect of xylitol.

In vivo intersegmental motion of the cervical spine using an inverse kinematics procedure

BACKGROUND

The main functions of the cervical spine are the stabilization and the orientation of the head. Pathologies are complex and difficult to diagnose. The first sign of the dysfunction is an abnormal intervertebral motion. It is the purpose of this feasibility study to determine the intersegmental motions and loading conditions of the cervical spine in vivo with standard clinical investigation methods.

METHODS

We propose a new approach which merges full flexion-extension X-ray images, and continuous motion of the whole cervical spine obtained with a tracking motion system. These data were used as input for a subject-specific rigid body model of the cervical spine computed with the software MSC.Adams. This model simulates the cervical spine extension/flexion, the intervertebral motions are deduced using an inverse kinematics procedure.

FINDINGS

Subject-specific rigid body models were computed from data of two subjects. The intersegmental motion and loading conditions were calculated. We found that the loading amplitudes depended on the intervertebral level, and that subject specific patterns were highlighted. We noticed an unsymmetrical behavior in flexion and extension. Furthermore intervertebral rotations were correlated with the global motion of the cervical spine.

INTERPRETATION

A subject-specific rigid body model merged data from classical flexion-extension radiographs and noninvasive external motion capture. Our approach is based on inverse kinematics allowing the estimation of the intervertebral motion and mechanical behavior of the cervical spine in vivo, which gives valuable information concerning biomechanics of the cervical spine in vivo for cervical spine clinical investigation.

Management of facial necrotizing fasciitis

Necrotizing fasciitis is a progressive, life-threatening, bacterial infection of the skin, the subcutaneous tissue and the underlying fascia, in most cases caused by ss-hemolytic group A streptococcus. Only early diagnosis and aggressive therapy including broad spectrum antibiotics and surgical intervention can avoid systemic toxicity with a high mortality rate. This uncommon disease generally occurs in the lower extremities and trunk, and only rarely affects the head and neck region. When located in the face necrotizing fasciitis is associated with severe cosmetic and functional restrictions due to the invasive infection and often to the necessary surgical treatment. Generally surgical intervention cannot be performed in the face as aggressively as in the extremities and trunk, since a lot of vital structures are found in a relatively small area. In the following article, we present the successful diagnostic and therapeutic management of an isolated facial necrotizing fasciitis as a consequence of a nasal bone fracture with a minor dermal cut.

Hybrid HIV/MSCV LTR enhances transgene expression of lentiviral vectors in human CD34(+) hematopoietic cells

HIV-based lentiviral vectors can transduce nondividing cells, an important advantage over murine leukemia virus (MLV)-based vectors when transducing slowly dividing hematopoietic stem cells. However, we find that in human CD34(+) hematopoietic cells, the HIV-based vectors with an internal cytomegalovirus (CMV) promoter express transgenes 100- to 1,000-fold less than the MLV-based retroviral vector murine stem cell virus (MSCV). To increase the expression of the integrated lentivirus, we replaced CMV promoter with that of the Rous sarcoma virus or MSCV and obtained a modest augmentation in expression. A more dramatic effect was seen when the CMV enhancer/promoter was removed and the HIV long-terminal repeat (LTR) was replaced by a novel HIV/MSCV hybrid LTR. This vector retains the ability to transduce nondividing cells but now expresses its transgene (enhanced green fluorescent protein) 10- to 100-fold greater than the original HIV-based vector. When compared under identical conditions, the HIV vector with the hybrid LTR transduced a higher percentage of CD34(+) cells than the MSCV-based retroviral vector (19.4% versus 2.4%). The number of transduced cells and level of transgene expression remain constant over 5-8 weeks as determined by long-term culture-initiating cells, fluoresence-activated cell sorting, and nonobese diabetic/severe combined immunodeficiency repopulation assay.

Nuclear localization or inclusion body formation of ataxin-2 are not necessary for SCA2 pathogenesis in mouse or human

Instability of CAG DNA trinucleotide repeats is the mutational mechanism for several neurodegenerative diseases resulting in the expansion of a polyglutamine (polyQ) tract. Proteins with long polyQ tracts have an increased tendency to aggregate, often as truncated fragments forming ubiquitinated intranuclear inclusion bodies. We examined whether similar features define spinocerebellar ataxia type 2 (SCA2) pathogenesis using cultured cells, human brains and transgenic mouse lines. In SCA2 brains, we found cytoplasmic, but not nuclear, microaggregates. Mice expressing ataxin-2 with Q58 showed progressive functional deficits accompanied by loss of the Purkinje cell dendritic arbor and finally loss of Purkinje cells. Despite similar functional deficits and anatomical changes observed in ataxin-1[Q80] transgenic lines, ataxin-2[Q58] remained cytoplasmic without detectable ubiquitination.

Association of diabetes mellitus and chronic hepatitis C virus infection

While patients with liver disease are known to have a higher prevalence of glucose intolerance, preliminary studies suggest that hepatitis C virus (HCV) infection may be an additional risk factor for the development of diabetes mellitus. To further study the correlation of HCV infection and diabetes, we performed a retrospective analysis of 1,117 patients with chronic viral hepatitis and analyzed whether age, sex, race, hepatitis B virus (HBV) infection, HCV infection, and cirrhosis were independently associated with diabetes. In addition, a case-control study was conducted to determine the seroprevalence of HCV infection in a cohort of 594 diabetics and 377 clinic patients assessed for thyroid disease. In the former study after the exclusion of patients with conditions predisposing to hyperglycemia, diabetes was observed in 21% of HCV-infected patients compared with 12% of HBV-infected subjects (P =.0004). Multivariate analysis revealed that HCV infection (P =.02) and age (P =.01) were independent predictors of diabetes. In the diabetes cohort, 4.2% of patients were found to be infected with HCV compared with 1.6% of control patients (P =.02). HCV genotype 2a was observed in 29% of HCV-RNA-positive diabetic patients versus 3% of local HCV-infected controls (P <.005). In conclusion, the data suggest a relatively strong association between HCV infection and diabetes, because diabetics have an increased frequency of HCV infection, particularly with genotype 2a. Furthermore, it is possible that HCV infection may serve as an additional risk factor for the development of diabetes, beyond that attributable to chronic liver disease alone.