Impact of a Genetic Diagnosis for a Child's Autism on Parental Perceptions.

Genetic testing is recommended as part of an autism assessment, and most parents support genetic testing for their minor children. However, the impact on parents of receiving a monogenetic/ copy number variant diagnosis for autism in their child is not well understood. To explore this, we surveyed and interviewed parents of children in the SPARK study, a study of autism that includes genetic testing. Surveys were administered one month before and one and 12 months after parents received their child's genetic result. Interviews were conducted approximately one month after results disclosure. A genetic diagnosis (GD) for their child appeared to reduce parents' sense of self-blame and feelings of guilt, and this impact was relatively stable. The data also indicate a modest impact on parents' actions related to the condition, perceptions of themselves, and some aspects of life planning for their child, as measured by quantitative instruments at one month and 12 months after receipt of results. Other measures of parental identity and expectations for their child, in contrast, showed little change following receipt of genetic findings. Overall, parents who were told that no GD was identified showed minimal changes in their responses over time. These results suggest a discernable but relatively limited impact of genetic test results on parents of children with autism. These results should be reassuring to clinicians caring for children with autism and are consistent with studies in other areas of medicine that have suggested that genetic results tend to have fewer effects-negative or positive-than were anticipated.

Expression of presynaptic markers in a neurodevelopmental animal model with relevance to schizophrenia.

Administration of N-methyl-D-aspartate receptor antagonist phencyclidine (PCP) to rat pups at postnatal day (PND) 7, 9, and 11 [neonatal PCP (neoPCP) model] induces cognitive deficits similar to those observed in schizophrenia. Expression of presynaptic SNARE protein, synaptosomal-associated protein of 25 kDa (Snap25), has been shown to be downregulated in postmortem brains from patients with schizophrenia. The present study was designed to investigate the long-term effects of neoPCP administration on expression of presynaptic markers altered in schizophrenia. Using radioactive in-situ hybridization, the expression of Snap25 was measured in the prefrontal cortex and the hippocampal formation (CA1, CA3, CA4, and dentate gyrus) at PND 29 and 80 in neoPCP and control rats. As a secondary presynaptic marker, the expressional level of synaptophysin was also measured in the same areas. Stereological estimation of the number of neurons and volume was used to exclude potential bias in cell numbers. A significant reduction in the expression of Snap25 in the hippocampal CA4 region was observed in adult neoPCP rats (PND 80, P<0.01), but not in preadolescent rats (PND 29), indicating a late developmental manifestation of a presynaptic pathology. The number of neurons and volume of the CA4 region showed no change in PCP rats compared with the controls. Furthermore, expression of another presynaptic marker, synaptophysin, remained unaffected by the PCP treatment. These findings indicate that perinatal PCP injections induce a delayed presynaptic impact on the vesicle fusion machinery in a brain region important for cognitive processes.

Differential expression of parvalbumin in neonatal phencyclidine-treated rats and socially isolated rats.

Decreased parvalbumin expression is a hallmark of the pathophysiology of schizophrenia and has been associated with abnormal cognitive processing and decreased network specificity. It is not known whether this decrease is due to reduced expression of the parvalbumin protein or degeneration of parvalbumin-positive interneurons (PV(+) interneurons). In this study, we examined PV(+) expression in two rat models of cognitive dysfunction in schizophrenia: the environmental social isolation (SI) and pharmacological neonatal phencyclidine (neoPCP) models. Using a stereological method, the optical fractionator, we counted neurons, PV(+) interneurons, and glial cells in the medial prefrontal cortex (mPFC) and hippocampus (HPC). In addition, we quantified the mRNA level of parvalbumin in the mPFC. There was a statistically significant reduction in the number of PV(+) interneurons (p = 0.021) and glial cells (p = 0.024) in the mPFC of neonatal phencyclidine rats, but not in SI rats. We observed no alterations in the total number of neurons, hippocampal PV(+) interneurons, parvalbumin mRNA expression or volume of the mPFC or HPC in the two models. Thus, as the total number of neurons remains unchanged following phencyclidine (PCP) treatment, we suggest that the decreased number of counted PV(+) interneurons represents a reduced parvalbumin protein expression below immunohistochemical detection limit rather than a true cell loss. Furthermore, these results indicate that the effect of neonatal PCP treatment is not limited to neuronal populations.

Developmental and diurnal expression of the synaptosomal-associated protein 25 (Snap25) in the rat pineal gland.

Snap25 (synaptosomal-associated protein) is a 25 kDa protein, belonging to the SNARE-family (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) of proteins, essential for synaptic and secretory vesicle exocytosis. Snap25 has by immunohistochemistry been demonstrated in the rat pineal gland but the biological importance of this is unknown. In this study, we demonstrate a high expression of mRNA encoding Snap25 in all parts of the rat pineal complex, the superficial-, and deep-pineal gland, as well as in the pineal stalk. Snap25 showed a low pineal expression during embryonic stages with a strong increase in expression levels just after birth. The expression showed no day/night variations. Neither removal of the sympathetic input to the pineal gland by superior cervical ganglionectomy nor bilateral decentralization of the superior cervical ganglia significantly affected the expression of Snap25 in the gland. The pineal expression levels of Snap25 were not changed following intraperitoneal injection of isoproterenol. The strong expression of Snap25 in the pineal gland suggests the presence of secretory granules and microvesicles in the rat pinealocyte supporting the concept of a vesicular release. At the transcriptional level, this Snap25-based release mechanism does not exhibit any diurnal rhythmicity and is regulated independently of the sympathetic nervous input to the gland.

Total numbers of neurons and glial cells in cortex and basal ganglia of aged brains with Down syndrome--a stereological study.

The total numbers of neurons and glial cells in the neocortex and basal ganglia in adults with Down syndrome (DS) were estimated with design-based stereological methods, providing quantitative data on brains affected by delayed development and accelerated aging. Cell numbers, volume of regions, and densities of neurons and glial cell subtypes were estimated in brains from 4 female DS subjects (mean age 66 years) and 6 female controls (mean age 70 years). The DS subjects were estimated to have about 40% fewer neocortical neurons in total (11.1 × 10(9) vs. 17.8 × 10(9), 2p ≤ 0.001) and almost 30% fewer neocortical glial cells with no overlap to controls (12.8 × 10(9) vs. 18.2 × 10(9), 2p = 0.004). In contrast, the total number of neurons in the basal ganglia was the same in the 2 groups, whereas the number of oligodendrocytes in the basal ganglia was reduced by almost 50% in DS (405 × 10(6) vs. 816 × 10(6), 2p = 0.01). We conclude that trisomy 21 affects cortical structures more than central gray matter emphasizing the differential impairment of brain development. Despite concomitant Alzheimer-like pathology, the neurodegenerative outcome in a DS brain deviates from common Alzheimer disease.