David Peakman

Comparison of G-, Q-, and R-banding in 28 cases of chromosomal abnormalities

Twenty-eight cases of chromosomal abnormalities were ascertained using G-banding. Seventeen of these had structural abnormalities of a complex nature and are discussed in detail. An independent assessment of chromosome abnormalities was carried out using sequential Q- and R-banding. In no case was there a difference in the identification of the abnormal chromosome, but in two cases a more precise localization or definition of the abnormality was obtained from the R-banded cells. In one case the initial diagnosis of the terminal deletion was altered to interstitial deletion; in the second case a break point in one chromosome involved in a reciprocal translocation was found to be in a different band by R-banding. In several others better delineation of break points or confirmation of complex abnormalities was obtained from the R-banded cells. R-banding was especially helpful in the localization of break points because of the color differentiation obtained with acridine orange. Q-banding was not found to have added any additional information. It was concluded from this study that the use of both G-banding and R-banding in complex abnormalities proved worthwhile.

Missing Y chromosome in juvenile chronic myelogenous leukemia

SummaryA child with Ph1-negative juvenile chronic myelogenous leukemia (CML) is presented. The only chromosomal abnormality in hematopoietic tissues consisted of an absent Y chromosome. While a missing Y chromosome in adult patients with CML may be associated with a better prognosis, the clinical course in our patient was as malignant as that usually observed in other children with Ph1-negative juvenile CML.This publication is No. 626 from the Department of Biophysics and Genetics, University of Colorado Medical Center.

Two cases of Down syndrome with unusual de novo translocation.

Two children with the clinical features of Down syndrome were found to have several unusual cell lines. In both cases the same reverse tandem translocation between two 21 chromosomes was present in one line. This may be an unstable rearrangement. In addition, the findings offer some support for current efforts to localize the portion of chromosome 21 responsible for clinical features of Down syndrome to band 21q22. Acridine orange R banding was found to be especially useful in the identification of the break points on the translocations. The origin of the abnormality was found to be paternal in one case and was indeterminate in the second.

551 CHROMOSOMAL MOSAICISM IN AMNIOTIC FLUID CELL CULTURES

The ability to differentiate true from pseudomosaicism is of major concern in prenatal diagnosis. Of 1000 amniotic fluids processed by in situ methods, a total of 26 demonstrated some degree of chromosomal mosaicism. Two, which had more than one colony possessing the same abnormality, were interpreted as true mosaicism. In both cases the same mosaicism (45,X/46,XX and 46,XX/47,XX+21) was shown to be present in the newborn or fetus. The remaining 24 cases, including 10 with trisomy 2, were interpreted as pseudomosaicism since only a single colony or partial colony demonstrated the aberrant chromosome complement. No phenotypic abnormalities have been noted in the babies delivered following a diagnosis of pseudomosaicism.

Screening for abnormalities of the Y chromosome

To the Editor: The recent report by Honig and Lindley (J. PZDIATm 78: 633, 1971 ) was most interesting to us. However, we would suggest an alternative explanation for an apparently specific deficiency of Hageman factor in some patients with the nephrotic syndrome. Recent workers have recognized that in many cases the nephrotic syndrome is associated with an inflammatory process, with or without the deposition of antibody-antigen complexes in the glomerular tuft. Ratnoff 1 and associates have described a key role for Hageman factor in mediating the inflammatory response, as well as having a potential for independently activating such crucial systems as the complement and kinin systems. We note that among Honig and Lindleys patients the only one with a clearly noninflammatory etiology for proteinuria, the patient with Lowes syndrome, was the only one whose level was well within normal values. We raise the possibility that some of the patients reported may have diminished levels of Hageman factor, not only on the basis of urinary loss but also as a result of immunologic or nonspecific activation of the Hageman factor with subsequent triggering of inflammatory systems in the glomerulus and elsewhere. Improvement of the level of Hageman factor with therapy treatment of the renal disease may then represent amelioration of the underlying disease which had been leading to consumption of the factor. Paul Edelson, M.D. Mark Ballow, M.D. Department o[ Pediatrics Yale University School o[ Medicine New Haven, Conn.

Screening of newborns for sex chromosomal abnormalities by a fluorescent technique

The importance of screening newborn infant populations for abnormalities of sex chromosomes has been demonstrated. We report an improved method of identifying Y chromosome abnormalities using the affinity of this chromosome for the fluorescent dye Quinacrine Hydrochloride. Cells obtained from Wharton Jelly of the umbilical cord were used. Also, these cells exhibit fluorescence of the Barr body in female cells, a hitherto undescribed phenomenon. This body differs significantly from the fluorescent Y body in its size, form and intensity of staining. Touch preparations of a freshly cut section of the cord were prepared and were stained with Quinacrine Hydrochloride. Blind sex determination was carried out on slides prepared from the cords of 249 infants. All of the 120 females were correctly diagnosed by the fluorescence of the Barr body. One hundred male specimens were correctly indentified by the presence of a fluorescent Y body and absence of a fluorescent Barr body.Three hundred fifty males have been screened for abnormalities in the number of Y chromosomes and thus far none have been found. A sequential staining technique using Quinacrine Hydrochloride and Carbol Fuchsin on the same specimen verified the identity of the fluorescent Barr body with the conventional Barr body. In addition to the obvious power of this technique in screening newborns for sex chromosomal abnormalities we believe it may be of great use in the rapid diagnosis of sex in utero.