Microdeletion syndromes, balanced translocations, and gene mapping.

High resolution prometaphase chromosome banding has allowed the detection of discrete chromosome aberrations which escaped earlier metaphase examinations. Consistent tiny deletions have been detected in some well established malformation syndromes: an interstitial deletion in 15q11/12 in the majority of patients with the Prader-Willi syndrome and in a minority of patients with the Angelman (happy puppet) syndrome; a terminal deletion of 17p13.3 in most patients examined with the Miller-Dieker syndrome; an interstitial deletion of 8q23.3/24.1 in a large majority of patients with the Giedion-Langer syndrome; an interstitial deletion of 11p13 in virtually all patients with the WAGR (Wilms' tumour-aniridia-gonadoblastoma-retardation) syndrome; and an interstitial deletion in 22q11 in about one third of patients with the DiGeorge sequence. In addition, a combination of chromosome prometaphase banding and DNA marker studies has allowed the localisation of the genes for retinoblastoma and for Wilms' tumour and the clarification of both the autosomal recessive nature of the mutation and the possible somatic mutations by which the normal allele can be lost in retina and kidney cells. After a number of X linked genes had been mapped, discrete deletions in the X chromosome were detected by prometaphase banding with specific attention paid to the sites of the gene(s) in males who had from one to up to four different X linked disorders plus mental retardation. Furthermore, the detection of balanced translocations in probands with disorders caused by autosomal dominant or X linked genes has allowed a better insight into the localisation of these genes. In some females with X linked disorders, balanced X; autosomal translocations have allowed the localisation of X linked genes at the breakpoint on the X chromosome. Balanced autosome; autosome translocations segregating with autosomal dominant conditions have provided some clues to the gene location of these conditions. In two conditions, Greig cephalopolysyndactyly and dominant aniridia, two translocation families with one common breakpoint have allowed quite a confident location of the genes at the common breakpoint at 7p13 and 11p13, respectively

A new method for assaying propantheline and its degradation product, xanthene-9- carboxylic acid using high performance liquid chromatography

A rapid, specific, and precise high-performance liquid chromatographic method is described for the simultaneous analysis of propantheline bromide and its hydrolysis product, xanthene-9-carboxylic acid. Reversed-phase chromatography was conducted using a mobile phase of 40:60, acetonitrile-0.05 M phosphate buffer (pH 2.5) delivered at 2 ml/min. Detection was at 254 nm. Methantheline bromide (internal standard), propantheline bromide, and xanthene-9-carboxylic acid gave retention times of 4.1, 5.4, and 8.3 min, respectively. Within-day, between-day, and total precision (CV) for assay of 15 mg/10 ml propantheline bromide are 1.2, 1.1, and 1.6%, respectively (n = 20). Similar precision was obtained for xanthene-9-carboxylic acid. The limit of detection was 2 ng. The assay is useful for routine quality assurance of propantheline in dosage forms and for stability and kinetic studies