together of positive and negative cells in 5-95% range.
Xga antigen on a red blood-cell
precursor of that cell and not by any other cell, which seems likely,7 12 one may conclude that complete inactivation of one of the two X chromosomes in each precursor of a red blood-cell does not occur in women in the frequency predicted by the Lyon hypothesis. The hypo-
thesis may hold for certain regions and loci, however. It now appears that the hypothesis must be tested locus by locus, preferably at the cellular level. We thank Dr. Amos Cahan, of Knickerbocker Biologicals, for a gift of anti-Xga. This research was supported by grants from the Medical Research Council (Canada), National Institutes of Health (GM 07950-02), and the National Foundation (U.S.A.). Departments of Zoology and Pædiatrics, University of Toronto,
and Research Institute, The Hospital for Sick Children, Toronto, Canada. Department of Pharmacology, University of Toronto. Rh Laboratory, University of Manitoba, Winnipeg, Canada.
T. EDWARD REED. NANCY E. SIMPSON. BRUCE CHOWN.
SIMULTANEOUS 18-TRISOMY AND 21-TRISOMY CLUSTER SIR,-Following the observation of two patients with the 18-trisomy syndrome in this small community,13 we noticed at the same time an unusual increase of Down’s syndrome (mongolism) among our newborns. The population in our area has been fairly stable in number and composition throughout the past decade. Since more than 99% of our deliveries are conducted in the hospitals, our hospitals serve a population of 30,000 (judged on the average birth-rate for South Dakota from 1954-61 14 : 26-54 per 1000
population). A check of the hospital records, supplemented by interrogations and questionnaires, revealed several interesting facts: (1) The overall incidence of 21-trisomies in our area is very high. From Jan. 1,1954, to Feb. 28, 1963, 6929 deliveries were registered in Watertown hospitals. In this period, 20 children with mongolism were born. The incidence-rate in our area would therefore be one mongoloid child per 346-5 deliveries. The expected rate of incidence is one mongoloid child per 714 deiiveries.l5 In Australia the reported rate of incidence is one mongoloid child per 688 live births.4 (2) In the reported period, 2 18-trisomy births were also registered. The expected rate, based on Smith’s report,3 would be 1-6 18-trisomy births for a comparable number of deliveries. However, since this syndrome has been known only for a few years, it appears possible that more have occurred but were not recognised or recorded in the early part of the studied period. (3) The occurrence of Down’s syndrome (mongolism) was not equally distributed throughout the studied period. The graphic presentation shows three distinct cluster formations (see figure). This is the first confirmation in this country of the Australian observation.16 12. Race, R. R., Sanger, R. Blood Groups in Man. Oxford, 1962. 13. Clin. Ped. 1963, 2, 25. 14. South Dakota Department of Health. Public Health Statistics. 15. Ped. Clin. N. Amer. May, 1963, p. 404. 16. Amer. J. publ. Hlth. 1962, 52, 813.
Cluster A lasted from Sept. 23, 1954, to May 24, 1956 (615 days), containing 7 mongoloids in 1370 deliveries, or 1 Down’s syndrome per 195-7 deliveries. Cluster B lasted from June 30, 1958, to June 6, 1960 (708 days), containing 8 mongoloids in 1437 deliveries, or 1 Down’s syndrome per 179-6 deliveries. Cluster C lasted from Dec. 17, 1961, to Feb. 8, 1963 (419 days). There is no indication that the period of this cluster is It contains 4 mongoloids, so far, in 711 deliveries; or over. 1 Down’s syndrome per 177-75 deliveries. If one adds the two 18-trisomy syndromes, the relative incidence for these two autosomic trisomies would be one in 118-5 deliveries.
Remarkably similar are the relative incidences of Down’s syndrome in each cluster. The length of the cluster is unpredictable; however, the peaks appear every 31/2 to 4 years. The simultaneous occurrence of an 18-trisomy cluster with a 21-trisomy cluster in one area has not hitherto been reported. The fact that both syndromes are autosomal trisomies, the coincidence of their appearance by time and location as well as the biphasic age-distribution of the mothers at birth of these children in both syndromes 1617 appears to be circumstantial evidence that they are caused by the same as yet unknown xtiological agent. We have no knowledge as to the cause of the unusual incidence and the cluster formations in our area, but further investigations are on the way and will be published later. E. H. HEINRICHS Department of Pediatrics, Bartron Clinic and Medical S. W. ALLEN, Jr. Arts Clinic, Watertown, P. S. NELSON. South Dakota. EXTRA ACROCENTRIC CHROMOSOME IN A CASE OF GIANT CAVERNOUS HÆMANGIOMA WITH SECONDARY THROMBOCYTOPENIA
SIR,-We describe here the chromosomal study of a baby, aged 21/2 years, with giant haemangioma. When the patient was 4 months of age, there appeared on the
thigh two circular reddish spots, which later changed to a deep wine colour and coarse texture. There was rapid growth on the entire left thigh and buttock. After 2 months traumatic purple spots appeared. At this time the patient was admitted to hospital with a diagnosis of giant hmmangioma, which, by skin biopsy, proved to be of the capillary type. Sclerotic treatment was tried with local infiltration of 25 ml. (12-5 g.) of ethanolamine oleate. The child was later readmitted owing to accentuation of the haemorrhagic phenomena. The haemangioma had extended to the entire posterior region of the left thigh and buttock. The left thigh had attained a circumference of 52 cm. in contrast to a circumference of 22 cm. of the other thigh. From the time of readmission the child presented petechiae and ecchymoses, but without haemorrhagic manifestations from the natural orifices. The hypothesis of giant cavernous haemangioma with secondary thrombocytopenia was confirmed by blood and bone-marrow examinations. It was learned from X-rays that the femur in the affected thigh was 2 cm. longer than the other. The patient was submitted to radiotherapy (120 kW, aluminum filter 3, 5 mA), receiving three series of 900r in the anterior,
back of the left
lateral, and posterior region of the left thigh. The patient was
to 90r for 2 minutes on a skin of 15 x 10 cm., with an interval of 10 days between each series. After treatment, palpation revealed slight sclerosis of the hxmangioma. During therapy the patient received bloodtransfusions. The thrombocytes, which had oscillated between 1000 and 22,000 per c.mm.,
previous levels within 5 days.
(in the press).