Fifty males with the fragile X [fra(X)] syndrome, which we consider synonymous with the Martin-Bell syndrome, were identified by a chromosome analysis of patients with developmental delays or mental retardation and family studies of known fra(X) pedigrees. These males were evaluated for autism using three criteria: 1) the DSM III diagnostic criteria for Infantile Autism; 2) the Autism Behavior Checklist (ABC); and 3) the Diagnostic Checklist for Behavior Disturbed Children, Form E2. Sixteen percent of patients fulfilled all of the DSM III criteria for Infantile Autism and an additional 30% fulfilled criteria for Infantile Autism Residual State. Thirty-one percent of patients had autism using the ABC checklist but none of the patients fit the classical Kanner syndrome as described by the E2 questionnaire. Some autistic traits were seen in almost all of the 50 fra(X) patients, including eye avoidance in 90%, handflapping, handbiting or handstereotypies in 88%, and language delays with language peculiarities, usually echolalic speech, in 96%. A pervasive lack of responsiveness was seen in 18% at their present age and in 44% in earlier childhood only. Autistic symptoms are common in the fra(X) syndrome. Therefore, any patient with developmental delays and autism or autistic manifestations should have a chromosomal analysis, including fra(X) examination.

Previous studies have reported immunoglobulin-positive neurons in Alzheimer's disease (AD) brains, an observation indicative of blood-brain barrier (BBB) breakdown. Recently, we demonstrated the nearly ubiquitous presence of brain-reactive autoantibodies in human sera. The significance of these observations to AD pathology is unknown. Here, we show that IgG-immunopositive neurons are abundant in brain regions exhibiting AD pathology, including intraneuronal amyloid-β(42) (Aβ(42)) and amyloid plaques, and confirm by western analysis that brain-reactive autoantibodies are nearly ubiquitous in human serum. To investigate a possible interrelationship between neuronal antibody binding and Aβ pathology, we tested the effects of human serum autoantibodies on the intraneuronal deposition of soluble Aβ(42) peptide in adult mouse neurons in vitro (organotypic brain slice cultures). Binding of human autoantibodies to mouse neurons dramatically increased the rate and extent of intraneuronal Aβ(42) accumulation in the mouse cerebral cortex and hippocampus. Additionally, individual sera exhibited variable potency related to their capacity to enhance intraneuronal Aβ(42) peptide accumulation and immunolabel neurons in AD brain sections. Replacement of human sera with antibodies targeting abundant neuronal surface proteins resulted in a comparable enhancement of Aβ(42) accumulation in mouse neurons. Overall, results suggest that brain-reactive autoantibodies are ubiquitous in the blood and that a defective BBB allows these antibodies to access the brain interstitium, bind to neuronal surfaces and enhance intraneuronal deposition of Aβ(42) in AD brains. Thus, in the context of BBB compromise, brain-reactive autoantibodies may be an important risk factor for the initiation and/or progression of AD as well as other neurodegenerative diseases.

Major psychiatric disorders have a complex genetic aetiology. The study of psychiatric phenotypes in individuals with malformation syndromes may allow one to search for the genes that confer an increased risk for the same psychiatric disorders in the general population. The present authors report on the psychiatric evaluations of 13 patients with classic or incomplete features of Rubinstein-Taybi syndrome (RTS), a multiple congenital anomaly syndrome mapped to 16p13.3, whose psychiatric diagnoses fell within a consistent spectrum, suggesting a possible relationship between RTS and these psychiatric disorders. The diagnoses clustered into mood disorders and the tic/obsessive compulsive disorder (OCD) spectrum; all tic/OCD diagnoses occurred in patients with classical RTS. It was of interest that neuroleptic-induced movement disorders and neuroleptic malignant syndrome were common. While no conclusions can be drawn about the prevalence of psychiatric disorders in RTS, the pattern of psychiatric diagnoses in these patients appear non-random, and the occurrence and severity of neuroleptic side-effects is striking. Given the suspected relationship of these complications with the serotonergic and dopaminergic systems, the present authors suggest that the gene locus for RTS should be investigated for genes related to the regulation of these neurotransmitters.

There are reports of sex chromosomal abnormalities including XXY, XYY, and fragile X karyotypes in autistic individuals, but structural autosomal defects have rarely been reported. This paper presents four patients with autism, mental retardation, minor dysmorphic features, and structural autosomal defects. These patients shared autistic features including fascination with inanimate objects, catastrophic reactions to changes in their environment or their daily routine, echolalia, and poor relatedness; IQ scores indicate mild to severe retardation. Their autosomal abnormalities included inversion/duplications of 3p and 16q, 5p+, and 17p-. Parental chromosomes were all normal. Chromosomal analysis should be performed on mentally retarded, autistic individuals, especially those with minor physical anomalies and no specific etiology for their retardation.

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