Combined with the availability of excellent animal models this makes RTT and MECP2-related disorders not only a fascinating and tractable subject for study, but the understanding that comes from such studies will likely provide insight into a wide spectrum of neurodevelopmental, neurological, and psychiatric diseases. The promise provided by the reversibility of disease in the mouse model of RTT has become and inspiration for the entire neurodevelopmental field and great hope exists that therapeutic options developed for RTT will prove useful

for other neurodevelopmental disorders.
Both categorical and Inhibitors,research,lifescience,medical dimensional approaches to diagnosis have been utilized, although in actual clinical practice diagnostic approaches (for many reasons) tend to be ideographic, ie, encompassing all the complexities of the specific individual.5 Categorical approaches have tended to dominate in official Inhibitors,research,lifescience,medical classification schemes, but are not incompatible with dimensional ones, eg, selection of an Docetaxel molecular weight arbitrary “cutoff point” for hypertension or intellectual disability. Categorical approaches have become much more sophisticated in recent years—notably with the advent of the research diagnostic criteria (RDC) Inhibitors,research,lifescience,medical adopted with DSM-III (which first officially recognized autism in 1980).6,7 Categorical systems have great value for record-keeping and statistical purposes but face some intrinsic challenges, eg, the problem of setting a specific diagnostic

threshold while recognizing “subthreshold” forms of conditions, dealing with co-occurring conditions (comorbidity), and addressing developmental change, as well as the enduring tension between narrow vs broader definitions. The latter reflects, in part, an intended use for research Inhibitors,research,lifescience,medical or more general clinical approaches. Inhibitors,research,lifescience,medical The

official approaches applied in DSM-IV and ICD-10 exemplify this difference, with DSM-IV being intended for both clinical and research use, while ICD-10 provides two different guides for these two purposes. Similarly, ICD-10, in general, discourages comorbidity while this is more acceptable in DSM-IV (see ref 4 for a discussion). The tensions between narrow vs broad definitions have important implications for service planning, as well as for research. For the latter purpose a very specific definition is often the goal while for purposes of service provision a broader diagnostic concept may be more appropriate. The latter is particularly an issue in the US where CYTH4 labels like autism may provide specific rights to service from schools and other services. As discussed subsequently, other issues arise given advances in science, eg, with the identification of genetic and other pathophysiological mechanisms. Dimensional approaches to diagnosis Dimensional approaches offer some considerable advantages, with instruments often having had extensive periods of development and well known psychometric properties, ie, of reliability.