The Prevalence and Characteristics of Children With Profound Autism, 15 Sites, United States, 2000-2016

OBJECTIVES

Autism spectrum disorder (autism) is a heterogeneous condition that poses challenges in describing the needs of individuals with autism and making prognoses about future outcomes. We applied a newly proposed definition of profound autism to surveillance data to estimate the percentage of children with autism who have profound autism and describe their sociodemographic and clinical characteristics.

METHODS

We analyzed population-based surveillance data from the Autism and Developmental Disabilities Monitoring Network for 20 135 children aged 8 years with autism during 2000-2016. Children were classified as having profound autism if they were nonverbal, were minimally verbal, or had an intelligence quotient <50.

RESULTS

The percentage of 8-year-old children with profound autism among those with autism was 26.7%. Compared with children with non-profound autism, children with profound autism were more likely to be female, from racial and ethnic minority groups, of low socioeconomic status, born preterm or with low birth weight; have self-injurious behaviors; have seizure disorders; and have lower adaptive scores. In 2016, the prevalence of profound autism was 4.6 per 1000 8-year-olds. The prevalence ratio (PR) of profound autism was higher among non-Hispanic Asian/Native Hawaiian/Other Pacific Islander (PR = 1.55; 95 CI, 1.38-1.73), non-Hispanic Black (PR = 1.76; 95% CI, 1.67-1.86), and Hispanic (PR = 1.50; 95% CI, 0.88-1.26) children than among non-Hispanic White children.

CONCLUSIONS

As the population of children with autism continues to change, describing and quantifying the population with profound autism is important for planning. Policies and programs could consider the needs of people with profound autism across the life span to ensure their needs are met.

Differential Performance of Social Communication Questionnaire Items in African American/Black vs. White Children

Screening for autism spectrum disorder (ASD) is an essential early step in the identification process and inaccurate screening may lead to significant delays in the onset of treatment. Past research has highlighted discrepancies in the performance of ASD screening tools such as the Social Communication Questionnaire (SCQ) among certain racial and ethnic groups. The current study explored the functioning of the SCQ among African American/Black and White respondents based on item level performance on the measure. Differential Item Functioning (DIF) analyses showed that 16 (41%) items of the SCQ functioned differently for African American/Black respondents when compared to White respondents. Implications, such as the potential for delayed diagnosis and treatment, and the influence on downstream outcomes, are discussed.

'They can stigmatize you': a qualitative assessment of the influence of school factors on engagement in care and medication adherence among adolescents with HIV in Western Kenya

School-related factors may influence retention in care and adherence to antiretroviral therapy (ART) among adolescents with human immunodeficiency virus (HIV). We analyzed data from in-depth interviews with 40 adolescents with HIV (aged 14 -19 years), 40 caregivers of adolescents with HIV, and 4 focus group discussions with healthcare workers to evaluate contextual factors affecting adherence to ART and clinic attendance among adolescents, with a focus on the school environment. Informed by Anderson's Model of Health Services Utilization, transcripts were systematically coded and synthesized to identify school-related themes. All groups identified the school environment as a critical barrier to engagement in HIV care and medication adherence for adolescents with HIV. Adolescent participants reported inflexible school schedules and disclosure to school staff as the biggest challenges adhering to clinic appointments and ART. Adolescents described experiencing stigma and discrimination by peers and school staff and would adjust when, where and how often they took ART to avoid inadvertent disclosure. Boarding school students faced challenges because they had limited private space or time. Caregivers were often instrumental in navigating school permissions, including identifying a treatment supporter among school staff. Additional research engaging school staff may guide interventions for schools to reduce stigma and improve adherence and retention.

CDC's "Learn the Signs. Act Early." Developmental Milestone Resources to Improve Early Identification of Children with Developmental Delays, Disorders, and Disabilities

Approximately 1 in 6 children in the US has a developmental delay, disorder, or disability (DD). Early identification of DDs can help families access services that empower children and families, and it can improve child outcomes. The "Learn the Signs. Act Early." (LTSAE) Program at the Centers for Disease Control and Prevention (CDC) encourages parents and providers to monitor every child's early development and act when there is a concern. In February 2022, LTSAE released revised materials that include updated developmental milestone checklists to better support ongoing conversations between families and professionals. This article describes the purpose of the checklists and how early childhood professionals can use these free resources to engage families in developmental monitoring.

Measuring state-level infant and toddler well-being in the United States: Gaps in data lead to gaps in understanding

Children who are nurtured, protected, and supported in the first years of life tend to have better individual outcomes and are more likely to grow to become healthy, productive adults. Child well-being varies across states, yet the field lacks a comprehensive review of infant and toddler indicators measured at the state-level. This paper reviews indicators of well-being from the prenatal period to three years that meet certain a priori criteria. Most of the child-level indicators identified were in the physical health domain; relatively fewer indicators were found in the early cognition and language or social-emotional-behavioral domains. While some states are making progress toward developing integrated early childhood data systems, more work is needed to provide robust data on infant and toddler development. These results highlight the need to develop a broader range of indicators of infant and toddler well-being and improve measurement sources to better inform policies and programs advancing population health.

Patterns of Special Education Eligibility and Age of First Autism Spectrum Disorder (ASD) Identification Among US Children with ASD

The study examined timing of autism spectrum disorder (ASD) identification in education versus health settings for 8-year-old children with ASD identified through records-based surveillance. The study also examined type of ASD symptoms noted within special education evaluations. Results indicated that children with records from only education sources had a median time to identification of ASD over a year later than children with records from health sources. Black children were more likely than White children to have records from only education sources. Restricted and repetitive behaviors were less frequently documented in educational evaluations resulting in developmental delay eligibility compared to specific ASD eligibility among children with ASD. Future research could explore strategies reduce age of identification in educational settings and increase equitable access to health evaluations.

Pica, Autism, and Other Disabilities

BACKGROUND AND OBJECTIVES

Pica, the repeated ingestion of nonfood items, can be life-threatening. Although case reports describe pica in children with autism spectrum disorder (ASD) or intellectual disability (ID), there has been little systematic study of pica prevalence. We assessed pica in children 30 to 68 months of age (median = 55.4 months) with and without ASD.

METHODS

Our sample from the Study to Explore Early Development, a multisite case-control study, included children with ASD (n = 1426), children with other developmental disabilities (DDs) (n = 1735), and general population-based controls (POPs) (n = 1578). We subdivided the ASD group according to whether children had ID and the DD group according to whether they had ID and/or some ASD characteristics. Standardized developmental assessments and/or questionnaires were used to define final study groups, subgroups, and pica. We examined pica prevalence in each group and compared ASD and DD groups and subgroups to the POP group using prevalence ratios adjusted for sociodemographic factors.

RESULTS

Compared with the prevalence of pica among POPs (3.5%), pica was higher in children with ASD (23.2%) and DD (8.4%), and in the following subgroups: ASD with ID (28.1%), ASD without ID (14.0%), DD with ID (9.7%), DD with ASD characteristics (12.0%), and DD with both ID and ASD characteristics (26.3%); however, pica prevalence was not elevated in children with DD with neither ID nor ASD characteristics (3.2%). Between-group differences remained after adjustment (adjusted prevalence ratio range 1.9-8.0, all P <.05).

CONCLUSIONS

Pica may be common in young children with ASD, ASD characteristics, and ID. These findings inform the specialized health care needs of these children.

Gastrointestinal Symptoms in 2- to 5-Year-Old Children in the Study to Explore Early Development

Gastrointestinal symptoms (GIS) are commonly reported in children with autism spectrum disorder (ASD). This multi-site study evaluated the prevalence of GIS in preschool-aged children with ASD/(n = 672), with other developmental delays (DD)/(n = 938), and children in the general population (POP)/(n = 851). After adjusting for covariates, children in the ASD group were over 3 times more likely to have parent-reported GIS than the POP group, and almost 2 times more likely than the DD group. Children with GIS from all groups had more behavioral and sleep problems. Within the ASD group, children with developmental regression had more GIS than those without; however, there were no differences in autism severity scores between children with and without GIS. These findings have implications for clinical management.

Association between pica and gastrointestinal symptoms in preschoolers with and without autism spectrum disorder: Study to Explore Early Development

BACKGROUND

Pica, the repeated ingestion of nonfood items, can result in gastrointestinal (GI) outcomes. Children with autism spectrum disorder (ASD) and other developmental disabilities (DDs) are disproportionately affected by both pica and GI symptoms. Study of the inter-relationship between pica, GI symptoms, and ASD/DD is limited.

OBJECTIVE/HYPOTHESIS

We assessed associations between pica and GI symptoms in preschool-aged children with and without ASD and other (non-ASD) DDs in the Study to Explore Early Development.

METHODS

Our sample included children with ASD (n = 1244), other DDs (n = 1593), and population (POP) controls (n = 1487). Data to define final case-control status, pica, and GI symptoms were from standardized developmental assessments/questionnaires. Prevalence ratios, adjusted for sociodemographic factors (aPRs), and 95% confidence intervals were derived from modified Poisson regression.

RESULTS

Within each group (ASD, DD, POP) and for the total sample, pica was associated with vomiting (aPR for total sample 2.6 [1.7, 4.0]), diarrhea (1.8 [1.4, 2.2]), and loose stools (1.8 [1.4, 2.2]). In the DD group, pica was associated with constipation (1.4 [1.03, 1.9]) and pain on stooling (1.8 [1.2, 2.6]). In analyses of the subgroup without pica, increases in GI symptoms were still evident in the ASD and DD groups compared to POP group.

CONCLUSION

These findings highlight an important adverse effect of pica, GI symptoms, in children with and without ASD and DDs; nonetheless, pica does not fully explain the increased risk for GI symptoms among children with ASD and DDs. These findings inform the specialized healthcare needs of children with ASD and other DDs.

A Preliminary Epidemiologic Study of Social (Pragmatic) Communication Disorder Relative to Autism Spectrum Disorder and Developmental Disability Without Social Communication Deficits

The goal of this preliminary investigation was to compare demographic and clinical characteristics in a sample of children with likely Social (Pragmatic) Communication Disorder (SCD) (N = 117) to those in children with possible (N = 118) and some (N = 126) SCD traits, other developmental delay (DD) (N = 91) and autism spectrum disorder (ASD) (N = 642). We used data from the Study to Explore Early Development (SEED), a multi-site case-control study. Items reflecting SCD DSM-5 criteria were selected from an autism diagnostic measure, with SCD categories identified by creating quartiles. Our results suggest that SCD may fall along a continuum involving elevated deficits (in comparison to DD with no SCD) in social communication and restricted and repetitive behavior that do not reach the clinical threshold for ASD.

Injury-related treatments and outcomes in preschool children with autism spectrum disorder: Study to Explore Early Development (SEED)

BACKGROUND

Evidence about injury management and outcomes in children with autism spectrum disorder (ASD) is limited.

METHOD

Cross-sectional analyses included children aged 30-68 months with at least one medically attended injury. Standardized diagnostic instruments determined ASD cases. Parent-reported injury treatments and outcomes were examined in ASD cases (n = 224) versus developmental delays/disorders (DD) (n = 188) and population (POP) (n = 267) controls, adjusting for child and family characteristics using logistic regression.

RESULTS

Injury characteristics were similar between groups. Most children (82.5%) had emergency care (EC) or hospitalization after injury. Nearly half (46.4%) ever received a medication or injection, mostly analgesics (53.4%) and local anesthetics (23.8%), while 9.4% ever received surgery, most often for open wound (47.0%) or fracture (16.7%). ASD group children were less likely than DD group children to receive medication/injection (41.1% vs. 53.2%, adjusted odds ratio [aOR] = 0.60 [0.40, 0.90]); receipt of EC/hospitalization and surgery were comparable. Children with ASD more often had surgery than POP children (14.3% vs. 4.9%, aOR = 2.62 [1.31, 5.25]); receipt of EC/hospitalization and medication/injection were similar. Loss of consciousness was uncommon (ASD = 6.3%, DD = 5.3%, POP = 3.4%), as was long-term or significant behavior change (ASD = 5.4%, DD = 3.2%, POP = 3.2%); differences were not significant.

CONCLUSIONS

Injured children with ASD received fewer medications/injections than children with non-ASD developmental delays/disorders and more surgical treatments than general population children. Injury management was otherwise similar between groups. Understanding whether these results reflect child or injury characteristics or provider perceptions about behaviors and pain thresholds of children with ASD, and how these may influence care, requires further study.

Community-based service use in preschool children with autism spectrum disorder and associations with insurance status

BACKGROUND

ASD-related services can improve outcomes for children, but less is known about service outside of school settings during preschool age. We aimed to describe amount and category of community-based service use among 3-5-year-old children with ASD and examine differences by health insurance.

METHODS

We used cross-sectional data on 792 children with ASD diagnoses in the Study to Explore Early Development, a community-based study of neurodevelopment with enrollment between 2012-2016. Mothers reported current child service use and insurance status at study entry. We used log-Poisson and logistic regression to compare service use by insurance group.

RESULTS

Nearly 40% of children were not receiving community-based services at study entry. Children with public insurance had fewer total services than children with private or both insurances. After adjustment for sociodemographic confounders, insurance status was not associated with types of different categories of community-based services. However, children with public insurance alone were least likely to receive community-based behavioral therapy and most likely to receive psychotropic medication compared to other insurances.

CONCLUSION

Many preschool-aged children do not receive community-based services, with receipt associated with insurance type. Increasing access and availability for evidence-based service, especially for beneficiaries of public insurance, may improve service use and outcomes.

Trends in documented co-occurring conditions in children with autism spectrum disorder, 2002-2010

BACKGROUND

Autism spectrumdisorder (ASD) commonly presents with co-occurring medical conditions (CoCs). Little is known about patterns in CoCs in a time of rising ASD prevalence.

AIMS

To describe trends in number and type of documented CoCs in 8-year-old children with ASD.

METHODS

We used Autism and Developmental Disabilities Monitoring Network (ADDM) data, a multi-source active surveillance system monitoring ASD prevalence among 8-year-old children across the US. Data from surveillance years 2002, 2006, 2008, and 2010 were used to describe trends in count, categories, and individual CoCs.

RESULTS

Mean number of CoCs increased from 0.94 CoCs in 2002 to 1.06 CoCs in 2010 (p < 0.001). The percentage of children with ASD with any CoC increased from 44.5% to 56.4% (p < 0.001). CoCs with the greatest increases were in general developmental disability (10.4% to 14.5%), language disorder (18.9% to 23.6%), and motor developmental disability (10.5% to 15.6%). Sex modified the relationship between developmental (P = 0.02) and psychiatric (P < 0.001) CoCs and surveillance year. Race/ethnicity modified the relationship between neurological conditions (P = 0.04) and surveillance year.

CONCLUSIONS

The increase in the percentage of children with ASD and CoCs may suggest the ASD phenotype has changed over time or clinicians are more likely to diagnose CoCs.

Comparison of autism spectrum disorder surveillance status based on two different diagnostic schemes: Findings from the Metropolitan Atlanta Developmental Disabilities Surveillance Program, 2012

For the first time, the Autism and Developmental Disabilities Monitoring Network (ADDM) at the Centers for Disease Control and Prevention (CDC) reported prevalence estimates based on two different diagnostic schemes in the 2014 surveillance period. Results found substantial agreement between surveillance case status based on Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition-Text Revision (DSM-IV-TR) criteria and DSM-5 criteria ASD (kappa = 0.85). No study has replicated this agreement in another independent sample of surveillance records. The objectives of this study were to (1) replicate agreement between surveillance status based on DSM-IV-TR criteria and DSM-5 criteria for ASD, (2) quantify the number of children who met surveillance status based on only DSM-IV-TR criteria and only DSM-5 criteria for ASD, and (3) evaluate differences in characteristics of these latter two groups of children. The study sample was 8-year-old children who had health and education records reviewed for ASD surveillance in metropolitan Atlanta, GA in the 2012 surveillance year. Results found substantial agreement between child's surveillance status using DSM-IV-TR criteria and DSM-5 criteria for ASD (kappa = 0.80). There were no differences in child race/ethnicity, child sex, or intellectual disability between surveillance status defined by DSM-IV-TR criteria and that defined by DSM-5 criteria. Children who met surveillance status based on DSM-IV-TR criteria, but not DSM-5 criteria, were more likely to have developmental concerns and evaluations in the first three years. Children who met surveillance status based on DSM-5 criteria, but not DSM-IV-TR criteria, were more likely to have been receiving autism-related services or previously diagnosed with ASD. These results suggest that surveillance status of ASD based on DSM-5 criteria is largely comparable to that based on DSM-IV-TR criteria, and identifies children with similar demographic and intellectual characteristics.

Screening for Autism with the SRS and SCQ: Variations across Demographic, Developmental and Behavioral Factors in Preschool Children

The Social Communication Questionnaire (SCQ) and the Social Responsiveness Scales (SRS) are commonly used screeners for autism spectrum disorder (ASD). Data from the Study to Explore Early Development were used to examine variations in the performance of these instruments by child characteristics and family demographics. For both instruments, specificity decreased as maternal education and family income decreased. Specificity was decreased with lower developmental functioning and higher behavior problems. This suggests that the false positive rates of the SRS and the SCQ are associated with child characteristics and family demographic factors. There is a need for ASD screeners that perform well across socioeconomic and child characteristics. Clinicians should be mindful of differential performance of these instruments in various groups of children.

Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years - Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2014

PROBLEM/CONDITION

Autism spectrum disorder (ASD).

PERIOD COVERED

2014.

DESCRIPTION OF SYSTEM

The Autism and Developmental Disabilities Monitoring (ADDM) Network is an active surveillance system that provides estimates of the prevalence of autism spectrum disorder (ASD) among children aged 8 years whose parents or guardians reside within 11 ADDM sites in the United States (Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin). ADDM surveillance is conducted in two phases. The first phase involves review and abstraction of comprehensive evaluations that were completed by professional service providers in the community. Staff completing record review and abstraction receive extensive training and supervision and are evaluated according to strict reliability standards to certify effective initial training, identify ongoing training needs, and ensure adherence to the prescribed methodology. Record review and abstraction occurs in a variety of data sources ranging from general pediatric health clinics to specialized programs serving children with developmental disabilities. In addition, most of the ADDM sites also review records for children who have received special education services in public schools. In the second phase of the study, all abstracted information is reviewed systematically by experienced clinicians to determine ASD case status. A child is considered to meet the surveillance case definition for ASD if he or she displays behaviors, as described on one or more comprehensive evaluations completed by community-based professional providers, consistent with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) diagnostic criteria for autistic disorder; pervasive developmental disorder-not otherwise specified (PDD-NOS, including atypical autism); or Asperger disorder. This report provides updated ASD prevalence estimates for children aged 8 years during the 2014 surveillance year, on the basis of DSM-IV-TR criteria, and describes characteristics of the population of children with ASD. In 2013, the American Psychiatric Association published the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which made considerable changes to ASD diagnostic criteria. The change in ASD diagnostic criteria might influence ADDM ASD prevalence estimates; therefore, most (85%) of the records used to determine prevalence estimates based on DSM-IV-TR criteria underwent additional review under a newly operationalized surveillance case definition for ASD consistent with the DSM-5 diagnostic criteria. Children meeting this new surveillance case definition could qualify on the basis of one or both of the following criteria, as documented in abstracted comprehensive evaluations: 1) behaviors consistent with the DSM-5 diagnostic features; and/or 2) an ASD diagnosis, whether based on DSM-IV-TR or DSM-5 diagnostic criteria. Stratified comparisons of the number of children meeting either of these two case definitions also are reported.

RESULTS

For 2014, the overall prevalence of ASD among the 11 ADDM sites was 16.8 per 1,000 (one in 59) children aged 8 years. Overall ASD prevalence estimates varied among sites, from 13.1-29.3 per 1,000 children aged 8 years. ASD prevalence estimates also varied by sex and race/ethnicity. Males were four times more likely than females to be identified with ASD. Prevalence estimates were higher for non-Hispanic white (henceforth, white) children compared with non-Hispanic black (henceforth, black) children, and both groups were more likely to be identified with ASD compared with Hispanic children. Among the nine sites with sufficient data on intellectual ability, 31% of children with ASD were classified in the range of intellectual disability (intelligence quotient [IQ] <70), 25% were in the borderline range (IQ 71-85), and 44% had IQ scores in the average to above average range (i.e., IQ >85). The distribution of intellectual ability varied by sex and race/ethnicity. Although mention of developmental concerns by age 36 months was documented for 85% of children with ASD, only 42% had a comprehensive evaluation on record by age 36 months. The median age of earliest known ASD diagnosis was 52 months and did not differ significantly by sex or race/ethnicity. For the targeted comparison of DSM-IV-TR and DSM-5 results, the number and characteristics of children meeting the newly operationalized DSM-5 case definition for ASD were similar to those meeting the DSM-IV-TR case definition, with DSM-IV-TR case counts exceeding DSM-5 counts by less than 5% and approximately 86% overlap between the two case definitions (kappa = 0.85).

INTERPRETATION

Findings from the ADDM Network, on the basis of 2014 data reported from 11 sites, provide updated population-based estimates of the prevalence of ASD among children aged 8 years in multiple communities in the United States. The overall ASD prevalence estimate of 16.8 per 1,000 children aged 8 years in 2014 is higher than previously reported estimates from the ADDM Network. Because the ADDM sites do not provide a representative sample of the entire United States, the combined prevalence estimates presented in this report cannot be generalized to all children aged 8 years in the United States. Consistent with reports from previous ADDM surveillance years, findings from 2014 were marked by variation in ASD prevalence when stratified by geographic area, sex, and level of intellectual ability. Differences in prevalence estimates between black and white children have diminished in most sites, but remained notable for Hispanic children. For 2014, results from application of the DSM-IV-TR and DSM-5 case definitions were similar, overall and when stratified by sex, race/ethnicity, DSM-IV-TR diagnostic subtype, or level of intellectual ability.

PUBLIC HEALTH ACTION

Beginning with surveillance year 2016, the DSM-5 case definition will serve as the basis for ADDM estimates of ASD prevalence in future surveillance reports. Although the DSM-IV-TR case definition will eventually be phased out, it will be applied in a limited geographic area to offer additional data for comparison. Future analyses will examine trends in the continued use of DSM-IV-TR diagnoses, such as autistic disorder, PDD-NOS, and Asperger disorder in health and education records, documentation of symptoms consistent with DSM-5 terminology, and how these trends might influence estimates of ASD prevalence over time. The latest findings from the ADDM Network provide evidence that the prevalence of ASD is higher than previously reported estimates and continues to vary among certain racial/ethnic groups and communities. With prevalence of ASD ranging from 13.1 to 29.3 per 1,000 children aged 8 years in different communities throughout the United States, the need for behavioral, educational, residential, and occupational services remains high, as does the need for increased research on both genetic and nongenetic risk factors for ASD.

Trends in the prevalence of autism spectrum disorder, cerebral palsy, hearing loss, intellectual disability, and vision impairment, metropolitan atlanta, 1991-2010

This study examined the prevalence and characteristics of autism spectrum disorder (ASD), cerebral palsy (CP), hearing loss (HL), intellectual disability (ID), and vision impairment (VI) over a 15-20 year time period, with specific focus on concurrent changes in ASD and ID prevalence. We used data from a population-based developmental disabilities surveillance program for 8-year-olds in metropolitan Atlanta. From 1991-2010, prevalence estimates of ID and HL were stable with slight increases in VI prevalence. CP prevalence was constant from 1993-2010. The average annual increase in ASD prevalence was 9.3% per year from 1996-2010, with a 269% increase from 4.2 per 1,000 in 1996 to 15.5 per 1,000 in 2010. From 2000-2010, the prevalence of ID without ASD was stable; during the same time, the prevalence of ASD with and without co-occurring ID increased by an average of 6.6% and 9.6% per year, respectively. ASD prevalence increases were found among both males and females, and among nearly all racial/ethnic subgroups and levels of intellectual ability. Average annual prevalence estimates from 1991-2010 underscore the significant community resources needed to provide early intervention and ongoing supports for children with ID (13.0 per 1,000), CP, (3.5 per 1,000), HL (1.4 per 1,000) and VI (1.3 in 1,000), with a growing urgency for children with ASD.

Population attributable fractions for three perinatal risk factors for autism spectrum disorders, 2002 and 2008 autism and developmental disabilities monitoring network

PURPOSE

Numerous studies establish associations between adverse perinatal outcomes/complications and autism spectrum disorder (ASD). There has been little assessment of population attributable fractions (PAFs).

METHODS

We estimated average ASD PAFs for preterm birth (PTB), small for gestational age (SGA), and Cesarean delivery (CD) in a U.S. population. Average PAF methodology accounts for risk factor co-occurrence. ASD cases were singleton non-Hispanic white, non-Hispanic black, and Hispanic children born in 1994 (n = 703) or 2000 (n = 1339) who resided in 48 U.S. counties included within eight Autism and Developmental Disabilities Monitoring Network sites. Cases were matched on birth year, sex, and maternal county of residence, race-ethnicity, age, and education to 20 controls from U.S. natality files.

RESULTS

For the 1994 cohort, average PAFs were 4.2%, 0.9%, and 7.9% for PTB, SGA, and CD, respectively. The summary PAF was 13.0% (1.7%-19.5%). For the 2000 cohort, average PAFs were 2.0%, 3.1%, and 6.7% for PTB, SGA, and CD, respectively, with a summary PAF of 11.8% (7.5%-15.9%).

CONCLUSIONS

Three perinatal risk factors notably contribute to ASD risk in a U.S. population. Because each factor represents multiple etiologic pathways, PAF estimates are best interpreted as the proportion of ASD attributable to having a suboptimal perinatal environment resulting in PTB, SGA, and/or CD.

Insulin and glucagon modulate hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity by affecting immunoreactive protein levels

The question of whether the effects of insulin and glucagon on hepatic 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity are mediated largely by changes in the phosphorylation state of the enzyme or by changes in the quantity of enzyme protein was investigated by measuring enzyme protein and mRNA levels. If phosphorylation/dephosphorylation is responsible for the observed changes in HMG-CoA reductase activity, one would not expect to see changes in immunoreactive protein or mRNA levels in response to induction of diabetes, administration of insulin, or administration of insulin and glucagon. It was found that hepatic HMG-CoA reductase mRNA levels were decreased to 12% of control in diabetic rats. Immunoreactive protein was reduced to essentially undetectable levels. Administration of insulin restored both mRNA and immunoreactive protein levels. Glucagon blocked these effects. Enzyme activity changes were fully accounted for by changes in HMG-CoA reductase mRNA and immunoreactive protein. Fasting caused parallel falls in HMG-CoA reductase activity and immunoreactive protein levels with a lesser effect on mRNA levels. The insulin-mediated changes in HMG-CoA reductase gene expression correlated well with changes in blood glucose levels, indicating a physiological effect. Taken together, these results indicate that insulin and glucagon regulate HMG-CoA reductase gene expression largely at the level of enzyme protein through changes in mRNA concentrations.

Reduced formation of lesions in the DNA of a multidrug-resistant L1210 subline selected for teniposide resistance

Earlier studies have suggested that higher cellular levels of teniposide (VM-26) are required for the inhibition of growth in L1210/VM-26 sublines than in parental L1210 cells. On the basis of this observation, we hypothesized that resistance to VM-26, which is partly attributed to multidrug resistance, also resulted in reduced formation of DNA lesions by the drug. In confirmation of this hypothesis, equitoxic concentrations of VM-26 produced fewer breaks in the DNA of LIa5 microM cells, the prototype L1210/VM-26 subline, than in that of L1210 cells. Previously, potassium cyanide (KCN) and verapamil were shown to increase the levels of VM-26 in LIa5 microM but not L1210 cells. These agents also selectively increased the formation of breaks in the DNA of LIa5 microM but not L1210 cells. The DNA unknotting assay with phage P4 DNA indicated equivalent DNA type II topoisomerase activity in nuclear extracts of LIa5 microM and L1210 cells. The factor that reduced the formation of breaks in cellular LIa5 microM DNA by VM-26 provided less protection against equitoxic levels of doxorubicin, to which LIa5 microM cells are cross-resistant.

Expressions of resistance and cross-resistance in teniposide-resistant L1210 cells

Resistance to teniposide (VM-26) by VM-26 selected resistant L1210 cells in culture was attributed to alterations in the flux of VM-26 across the plasma membrane and to functions of homogeneously staining regions that appeared on one or more chromosomes. In the present study, electrophoresis of membrane-cytosol fractions of these resistant sublines demonstrated a protein band, Mr 22 kd, that was not evident in similar fractions of drug-sensitive L1210 cells or three revertant sublines. The distribution of this protein among various cellular fractions could be altered by manipulation of the concentration of calcium ions. A representative subline, LIa5 microM, was observed to have vesicles that reacted with Sudan black B stain, an indication of altered lipid metabolism. The LIa5 microM subline was cross-resistant to etoposide, vincristine, doxorubicin, amsacrine, and actinomycin D. Concentrations of VM-26 that inhibited cell division to the same extent caused an accumulation of fewer cells in the G2 stage of cell division in LIa5 microM cultures than in L1210 cultures. These observations indicate that the LIa5 microM subline expressed multiple drug resistance, as well as changes in the expression of cytotoxicity to VM-26.

Pericentric inversion of chromosome 19: prenatal diagnosis and genetic counselling

During prenatal diagnosis for advanced maternal age, a pericentric inversion of a chromosome 19 was detected in a male fetus. The inversion was familial, transmitted to the fetus by the phenotypically normal mother. The pregnancy resulted in a term birth of a phenotypically normal male infant. Inversion 19 appears to be a rare abnormality with only seven families reported thus far including ours. Infants with duplication deficiencies for chromosome 19 have not been reported in these families. This may suggest an apparent suppression of crossing over and recombination within the inverted segment of chromosome 19 during meiosis.