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Iron is an essential nutrient for virtually all forms of life. Because of its redox properties and involvement in a wide range of biological processes, a number of qualitative and quantitative chemical tools have been developed to detect reduced (Fe 2+ ) and oxidized (Fe 3+ ) forms of iron in biomolecules. These types of measurements are not only important in detecting iron species in solution, but also in understanding iron distribution, accumulation, and role in physiological and pathological processes. Here, we use UV-vis spectrophotometry and three common chromogenic reagents, ferrozine, 2,2'-bipyridine, and 1,10-phenanthroline to detect and quantify the concentration of ferrous ions in aqueous solutions, owing to the unique absorption spectra, specific molar absorptivity, and characteristic colors of these Fe 2+ -chelator complexes. Our results show that the kinetics of the formation of the {Fe 2+ -(ferrozine) 3 } complex, but not the{Fe 2+ -(bipyridine) 3 } or the {Fe(II)-(phenanthroline) 3 } complexes depend on the concentration of the iron chelator, requiring up to 20 min to complete when close to stoichiometric ratios are employed. The molar absorptivity values of these complexes under excess chelator concentrations were ~ 10% to 15% higher than reported literature values (i.e. 31,500 ± 1500 M -1  cm -1 for ferrozine at 562 nm, 9950 ± 100 M -1  cm -1 for 2,2'-bipyridine at 522 nm, and 12,450 ± 370 M -1  cm -1 for 1,10-phenanthroline at 510 nm). Our results have important implications when quantifying iron in biological systems and reveal optimal experimental conditions that must be employed for the accurate measurements of ferrous ions, whether free in solution, or after reduction of protein-bound ferric ions., (Copyright © 2021. Published by Elsevier Inc.)

Data on features of regression and pre-regression developmental history in a case series of 53 girls and women with Rett syndrome are presented. Consistent with the diagnostic criteria, hand skills and verbal or non-verbal communication skills were the most common skills lost during regression. Play and motor skills were also lost in half the cases. Regression most commonly occurred between 12 and 18 months of age but was noted in a few cases before 6 months or after 36 months. Pre-regression developmental delays or abnormalities were noted in over two-thirds of cases, increasing to 85% of the youngest cases where parental reporting was likely to be more accurate. Age at regression was not associated with severity of physical and growth symptoms, and thus did not appear to be an index of neurological severity. There is a continuing need to further elucidate the pre- and post-regression features of Rett syndrome in order to aid early identification, diagnosis and referral for genotype mutation analysis., (Copyright 2002 Elsevier Science B.V.)

An international group recommends that papers relating phenotypes to genotypes involving mutations in the X chromosome gene MECP2 should provide a minimum data set reporting the range of disturbances frequently encountered in Rett Syndrome. A simple scoring system is suggested which will facilitate comparison among the various clinical profiles. Features are described which should prompt screening for MECP2 mutations.