1. Braun JM, Kalkbrenner A. {{Autism prevalence and precipitation: the potential for cross-level bias}}. {Arch Pediatr Adolesc Med};2009 (May);163(5):492; author reply 492-493.
2. Losh M, Adolphs R, Poe MD, Couture S, Penn D, Baranek GT, Piven J. Neuropsychological profile of autism and the broad autism phenotype. Arch Gen Psychiatry;2009 (May);66(5):518-526.
CONTEXT: Multiple articles describe a constellation of language, personality, and social-behavioral features present in relatives that mirror the symptom domains of autism, but are much milder in expression. Studies of this broad autism phenotype (BAP) may provide a potentially important complementary approach for detecting the genes causing autism and defining associated neural circuitry by identifying more refined phenotypes that can be measured quantitatively in both affected and unaffected individuals and that are tied to functioning in particular regions of the brain. OBJECTIVE: To gain insight into neuropsychological features that index genetic liability to autism. DESIGN: Case-control study. SETTING: The general community. PARTICIPANTS: Thirty-eight high-functioning individuals with autism and parents of autistic individuals, both with and without the BAP (n = 83), as well as control individuals. MAIN OUTCOME MEASURES: A comprehensive battery of neuropsychological tasks assessing social cognition, executive function, and global vs local processing strategies (central coherence). RESULTS: Both individuals with autism and parents with the BAP differed from controls on measures of social cognition, with performance in the other 2 domains being more similar to controls. CONCLUSIONS: Data suggest that the social cognitive domain may be an important target for linking phenotype to cognitive process to brain structure in autism and may ultimately provide insight into the genes involved in autism.
3. Luyster R, Gotham K, Guthrie W, Coffing M, Petrak R, Pierce K, Bishop S, Esler A, Hus V, Oti R, Richler J, Risi S, Lord C. {{The Autism Diagnostic Observation Schedule-Toddler Module: A New Module of a Standardized Diagnostic Measure for Autism Spectrum Disorders}}. {J Autism Dev Disord};2009 (May 5)
The Autism Diagnostic Observation Schedule (ADOS; Lord et al., J Autism Dev Disord, 30(3):205-223, 2000) is widely accepted as a « gold standard » diagnostic instrument, but it is of restricted utility with very young children. The purpose of the current project was to modify the ADOS for use in children under 30 months of age. A modified ADOS, the ADOS Toddler Module (or Module T), was used in 360 evaluations. Participants included 182 children with best estimate diagnoses of ASD, non-spectrum developmental delay or typical development. A final set of protocol and algorithm items was selected based on their ability to discriminate the diagnostic groups. The traditional algorithm « cutoffs » approach yielded high sensitivity and specificity, and a new range of concern approach was proposed.
4. Mosconi MW, Cody-Hazlett H, Poe MD, Gerig G, Gimpel-Smith R, Piven J.{{ Longitudinal study of amygdala volume and joint attention in 2- to 4-year-old children with autism}}. {Arch Gen Psychiatry};2009 (May);66(5):509-516.
CONTEXT: Cerebral cortical volume enlargement has been reported in 2- to 4-year-olds with autism. Little is known about the volume of subregions during this period of development. The amygdala is hypothesized to be abnormal in volume and related to core clinical features in autism. OBJECTIVES: To examine amygdala volume at 2 years with follow-up at 4 years of age in children with autism and to explore the relationship between amygdala volume and selected behavioral features of autism. DESIGN: Longitudinal magnetic resonance imaging study. SETTING: University medical setting. PARTICIPANTS: Fifty autistic and 33 control (11 developmentally delayed, 22 typically developing) children between 18 and 35 months (2 years) of age followed up at 42 to 59 months (4 years) of age. MAIN OUTCOME MEASURES: Amygdala volumes in relation to joint attention ability measured with a new observational coding system, the Social Orienting Continuum and Response Scale; group comparisons including total tissue volume, sex, IQ, and age as covariates. RESULTS: Amygdala enlargement was observed in subjects with autism at both 2 and 4 years of age. Significant change over time in volume was observed, although the rate of change did not differ between groups. Amygdala volume was associated with joint attention ability at age 4 years in subjects with autism. CONCLUSIONS: The amygdala is enlarged in autism relative to controls by age 2 years but shows no relative increase in magnitude between 2 and 4 years of age. A significant association between amygdala volume and joint attention suggests that alterations to this structure may be linked to a core deficit of autism.
5. O’Connor RD, Zayzafoon M, Farach-Carson MC, Schanen NC. Mecp2 {{Deficiency Decreases Bone Formation and Reduces Bone Volume in a Rodent Model of Rett Syndrome}}. {Bone};2009 (May 1)
Rett Syndrome (RTT), a neurological disorder characterized by neurological impairment and a high frequency of osteopenia which often manifests early in childhood, most often is caused by inactivating mutations in the X-linked gene encoding a regulator of epigenetic gene expression, methyl CpG binding protein, MeCP2. Clinical data show that, along with neurological defects, females with RTT frequently have marked decreases in Bone Mineral Density (BMD) beyond that expected from disuse atrophy. To investigate the relationship between loss of Mecp2 and reduced BMD, we used a Mecp2 null mouse model, Mecp2(-/yBIRD), for our histological and biochemical studies. Mecp2(-/yBIRD) mice have significantly shorter femurs and an overall reduced skeletal size compared to wild-type mice by post-natal day 60 (P60). Histological and histomorphometric studies identified growth plate abnormalities as well as decreased cortical and trabecular bone in P21 and especially in P60 Mecp2(-/yBIRD) mice. Dynamic histomorphometry revealed decreased Mineral Apposition Rates (MAR) in Mecp2 null femoral trabecular bone as well as in calvarial bone samples. While changes in MAR of cortical bone were not significant, loss of Mecp2 significantly reduced cortical, trabecular and calvarial bone volume compared with age-matched wild-type animals. These differences indicate that Mecp2 deficiency leads to osteoblast dysfunction, which translates into reduced osteoid deposition accounting for the reduced bone volume phenotype. While individual variations were observed in OPG and Rankl concentrations, molar ratios of OPG:Rankl at P21 and P60 were comparable between wild-type and Mecp2(-/yBIRD) mice and showed a consistent excess of OPG. In tibial sections, TRAP staining demonstrated equivalent osteoclast number per bone surface measurements between wild-type and null animals. Our work with a Mecp2 null mouse model suggests epigenetic regulation of bone in the Mecp2(-/yBIRD) mice which is associated with decreased osteoblast activity rather than increased osteoclastic bone loss.
