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REPRODUCTION AND MEIOSIS IN XYY
831 come to term as
female infants with Turner’s
remainder being aborted spontaneously. This study was supported by the Medical
syndrome, the
Research Council of
ranncin-
Department of Anatomy, McMaster University,
Hamilton, Ontario, Canada.
DAVID H. CARR.
REPRODUCTION AND MEIOSIS IN XYY SIR,- The XYY sex-chromosome constitution is of unusual interest, because it seems to predispose to aggressive behaviour, mental subnormality, and tall stature.l Although XYY males have been reportedno data have been presented to our knowledge on the transmission of the extra Y chromosome to their offspring or on the behaviour of their chromosomes in meiosis. We here present findings on both. We studied the 7 children of an XYY man: 6 sons and 1 daughter. The 6 sons all had normal XY sex-chromosome complements, and the daughter had a normal XX constitution. The index case in the family was the daughter’s only child. This boy, who seems chromosomally normal, has mental
retardation, multiple anomalies, and tyrosinuria due to a newly delineated inborn error, tyrosine-transaminase deficiency.a The finding of XYY sex-chromosome constitution in his grandfather, whose leucocyte cultures do not show mosaicism, was therefore entirely unexpected. The fact that all 6 sons of the XYY man were XY is notable. Four classes of gametes are possible if secondary nondisj unction occurs in the first meiotic division in such males: X, YY, XY, and Y. Union of these gametes with X-bearing ova would produce XX, XYY, XXY, and XY zygotes. Thus, female offspring might all be expected to be normal, whereas 2 of the 3 types of males might be expected to be chromosomally abnormal. Neither XXY nor XYY was observed in the 6 sons, suggesting that selection may occur toward euploidy at either meiotic, gametic, and/or zygotic levels. Meiotic studies were refused by this man, but were subsequently carried out on another XYY male with no known offspring. Two leucocyte cultures and a testicular fibroblast culture showed XYY sex-chromosome constitution with no suggestion of mosaicism. A testicular biopsy-specimen was processed for meiotic studies by a modification of the technique described by Evans et al.4 Spermatogonial metaphases were scarce, but all twenty-two examined seemed to have only one Y chromosome. Seventeen of the twenty-two contained 46 chromosomes; eleven of these were karyotyped and showed a normal XY pattern. Of the non-modal cells, four had 45 chromosomes, which upon karyotyping showed scattered losses, and one had 47 chromosomes but contained only a single Y chromosome. Diakinesis and first-meiotic-metaphase figures were plentiful. Of a hundred and fifty-five cells examined none was clearly found to contain two Y chromosomes. Representative cells shown in the accompanying figure demonstrate several typical configurations of the XY bivalent and the X and Y univalents. Although some of these were initially felt to contain two Y chromosomes, comparison with meiotic figures of four chromosomally normal men showed no discernible differences in the various configurations of the sex chromosomes or in the relative frequencies of each type of configuration. Karyotypes of secondary spermatocytes were difficult to interpret, but thirty-four of thirty-nine figures examined contained 23 chromosomes; the other five contained 24-karyotypes of these did not show conclusive evidence as to the presence or absence of two Y chromosomes. 1.
Jacobs, P. A., Brunton, M., Melville, M. M., Brittain, R. P. Nature, Lond. 1965, 208, 1351. 2. Hauschka, T. S., Hasson, J. E., Goldstein, M. N., Koept, G. F., Sandberg, A. Am. J. hum. Genet. 1962, 14, 22. Tzoneva-Maneva, M. T., Bosajieva, E., Petrov, B. Lancet, 1966, i, 1000. 3. Campbell, R. A., Buist, N. R. M., Jacinto, E. Y., Koler, R. D., Hecht, F., Jones, R. T., Society for Pediatric Research (abstract). Atlantic 4.
City, 1967. Evans, E. P., Breckon, G., Ford, C. E. Cytogenetics, 1964. 3,
289.
Meiotic preparations from
an
XYY male.
Representative diplotene-diakinesis figures showing: (A) XY bivalent with commonly observed J-shaped configuration of the Y chromosome; (B) XY bivalent with folding of the Y chromosome as in (A), but giving the appearance of two separate parallel strands; (C) X and Y univalents separated; (D) examples of X and Y chromofrom other cells. All these configurations from normal XY males. somes
were
also observed in meiotic
preparations
These findings, although preliminary, suggest that selection toward chromosomally normal spermatocytes occurs before meiosis in XYY males. The mechanism responsible for this selection is unknown, but may be related to a similar one known to occur normally in the male creeping vole (Microtus oregoni), in which the somatic cells have an XY sex-chromosome constitution and the germ cells a YO constitution.5 This study was supported in part by grants HD 01343 and CA 07941, and from the Children’s Bureau. Department of Pediatrics, University of Oregon Medical School, Portland, Oregon 97201, and Fairview Hospital and Training Center, Salem, Oregon. Metabolic Division, Children’s Hospital of Los Angeles and Department of Pediatrics, University of Southern California, Los Angeles, California 90027. Department of Pediatrics (Crippled Children’s Division) and Division of Experimental Medicine, University of Oregon Medical School, Portland, Oregon 97201.
U.S. Public Health Service genetics programme grants
HAVELOCK THOMPSON.
JOHN
MELNYK.
FREDERICK HECHT.
TRISOMY 21 OR 22 IN DOWN’S SYNDROME? SIR,-The letter of Dr. Back and his colleagues 6 prompts us to report here a possible method of identifying the G-group chromosome involved in Down’s syndrome. We are specially interested’in the possibility of classifying the meiotic chromosomes in man in the same sequence as the standardised Denver karyotype pattern for mitotic 5. 6.
Ohno, S., Jainchill, J., Stenius, C. ibid. 1963, 2, 232. Back, F., Dormer, P., Baumann, P., Olbrich, E. Lancet, 1967, i, 1228.
female infants with Turner’s
remainder being aborted spontaneously. This study was supported by the Medical
syndrome, the
Research Council of
ranncin-
Department of Anatomy, McMaster University,
Hamilton, Ontario, Canada.
DAVID H. CARR.
REPRODUCTION AND MEIOSIS IN XYY SIR,- The XYY sex-chromosome constitution is of unusual interest, because it seems to predispose to aggressive behaviour, mental subnormality, and tall stature.l Although XYY males have been reportedno data have been presented to our knowledge on the transmission of the extra Y chromosome to their offspring or on the behaviour of their chromosomes in meiosis. We here present findings on both. We studied the 7 children of an XYY man: 6 sons and 1 daughter. The 6 sons all had normal XY sex-chromosome complements, and the daughter had a normal XX constitution. The index case in the family was the daughter’s only child. This boy, who seems chromosomally normal, has mental
retardation, multiple anomalies, and tyrosinuria due to a newly delineated inborn error, tyrosine-transaminase deficiency.a The finding of XYY sex-chromosome constitution in his grandfather, whose leucocyte cultures do not show mosaicism, was therefore entirely unexpected. The fact that all 6 sons of the XYY man were XY is notable. Four classes of gametes are possible if secondary nondisj unction occurs in the first meiotic division in such males: X, YY, XY, and Y. Union of these gametes with X-bearing ova would produce XX, XYY, XXY, and XY zygotes. Thus, female offspring might all be expected to be normal, whereas 2 of the 3 types of males might be expected to be chromosomally abnormal. Neither XXY nor XYY was observed in the 6 sons, suggesting that selection may occur toward euploidy at either meiotic, gametic, and/or zygotic levels. Meiotic studies were refused by this man, but were subsequently carried out on another XYY male with no known offspring. Two leucocyte cultures and a testicular fibroblast culture showed XYY sex-chromosome constitution with no suggestion of mosaicism. A testicular biopsy-specimen was processed for meiotic studies by a modification of the technique described by Evans et al.4 Spermatogonial metaphases were scarce, but all twenty-two examined seemed to have only one Y chromosome. Seventeen of the twenty-two contained 46 chromosomes; eleven of these were karyotyped and showed a normal XY pattern. Of the non-modal cells, four had 45 chromosomes, which upon karyotyping showed scattered losses, and one had 47 chromosomes but contained only a single Y chromosome. Diakinesis and first-meiotic-metaphase figures were plentiful. Of a hundred and fifty-five cells examined none was clearly found to contain two Y chromosomes. Representative cells shown in the accompanying figure demonstrate several typical configurations of the XY bivalent and the X and Y univalents. Although some of these were initially felt to contain two Y chromosomes, comparison with meiotic figures of four chromosomally normal men showed no discernible differences in the various configurations of the sex chromosomes or in the relative frequencies of each type of configuration. Karyotypes of secondary spermatocytes were difficult to interpret, but thirty-four of thirty-nine figures examined contained 23 chromosomes; the other five contained 24-karyotypes of these did not show conclusive evidence as to the presence or absence of two Y chromosomes. 1.
Jacobs, P. A., Brunton, M., Melville, M. M., Brittain, R. P. Nature, Lond. 1965, 208, 1351. 2. Hauschka, T. S., Hasson, J. E., Goldstein, M. N., Koept, G. F., Sandberg, A. Am. J. hum. Genet. 1962, 14, 22. Tzoneva-Maneva, M. T., Bosajieva, E., Petrov, B. Lancet, 1966, i, 1000. 3. Campbell, R. A., Buist, N. R. M., Jacinto, E. Y., Koler, R. D., Hecht, F., Jones, R. T., Society for Pediatric Research (abstract). Atlantic 4.
City, 1967. Evans, E. P., Breckon, G., Ford, C. E. Cytogenetics, 1964. 3,
289.
Meiotic preparations from
an
XYY male.
Representative diplotene-diakinesis figures showing: (A) XY bivalent with commonly observed J-shaped configuration of the Y chromosome; (B) XY bivalent with folding of the Y chromosome as in (A), but giving the appearance of two separate parallel strands; (C) X and Y univalents separated; (D) examples of X and Y chromofrom other cells. All these configurations from normal XY males. somes
were
also observed in meiotic
preparations
These findings, although preliminary, suggest that selection toward chromosomally normal spermatocytes occurs before meiosis in XYY males. The mechanism responsible for this selection is unknown, but may be related to a similar one known to occur normally in the male creeping vole (Microtus oregoni), in which the somatic cells have an XY sex-chromosome constitution and the germ cells a YO constitution.5 This study was supported in part by grants HD 01343 and CA 07941, and from the Children’s Bureau. Department of Pediatrics, University of Oregon Medical School, Portland, Oregon 97201, and Fairview Hospital and Training Center, Salem, Oregon. Metabolic Division, Children’s Hospital of Los Angeles and Department of Pediatrics, University of Southern California, Los Angeles, California 90027. Department of Pediatrics (Crippled Children’s Division) and Division of Experimental Medicine, University of Oregon Medical School, Portland, Oregon 97201.
U.S. Public Health Service genetics programme grants
HAVELOCK THOMPSON.
JOHN
MELNYK.
FREDERICK HECHT.
TRISOMY 21 OR 22 IN DOWN’S SYNDROME? SIR,-The letter of Dr. Back and his colleagues 6 prompts us to report here a possible method of identifying the G-group chromosome involved in Down’s syndrome. We are specially interested’in the possibility of classifying the meiotic chromosomes in man in the same sequence as the standardised Denver karyotype pattern for mitotic 5. 6.
Ohno, S., Jainchill, J., Stenius, C. ibid. 1963, 2, 232. Back, F., Dormer, P., Baumann, P., Olbrich, E. Lancet, 1967, i, 1228.