J Med Genet: first published as 10.1136/jmg.10.1.74 on 1 March 1973. Downloaded from Journal of Medical (1973). 10, 74.

Human Dicentric Y Case Report and Review of the Literature MAIMON M. COHEN,* MARGARET H. MAcGILLIVRAY, VINCENT J. CAPRARO, and THOMAS A. ACETO

Divisions of Human Genetics and Endocrinology, Department of Pediatrics, State University of New York at Buffalo School of Medicine and Children's Hospital of Buffalo, Buffalo, New York, USA Summary. A phenotypic female with histological evidence of mixed gonadal dysgenesis, and 45,X/46,X,dic(Yq) mosaicism is described. A review of the litera- ture yielded 15 additional cases of dicentric Y chromosomes. Among the cases, a wide range ofvariation in phenotype, external genitalia, histology, and chromosomal findings was observed. Factors possibly contributing to such variability are dis- cussed and include: the exact site of breakage and exchange in the Y ; the timing of dicentric formation (meiotic vs mitotic); the occurrence of non-dis- junction; and the presence or absence of a in cells of the gonadal anlage during a critical ontogenic period.

Morphologically the human Y chromosome is, logical and cytogenetic variability. The possible probably, the most variable chromosome of the bases for such disparity are considered in this paper. human . Extreme variations of length have been observed both in normal individuals and in individuals with physical abnormalities (Makino Subjects and Methods et al, 1963; Gripenberg, 1964; Cohen, Shaw, and Case Report. L.P., an 11-year-old girl, was the MacCluer, 1966; McKenzie et al, 1972). Family product of a normal pregnancy but was born with an http://jmg.bmj.com/ studies have demonstrated that such length vari- enlarged clitoris, rugated labia majora, absence of labia minora, and posterior labial fusion (Fig. la). She was ation is heritable (Bishop, Blank, and Hunter, 1962; delivered by breech extraction and weighed 2500 g. At de la Chappelle et al, 1963; Borgaonkar et al, 1969; birth, a buccal smear was negative; serum electrolytes McKenzie et al, 1972). Additionally, a wide spec- and urinary 17-ketosteroids and pregnanetriol were trum of structural rearrangements, altering Y repeatedly found to be in the normal range. An intra- chromosome morphology, have been observed: venous pyelogram showed a double collecting system on deletions (Conen et al, 1961; Muldal and the left with no evidence of hydronephrosis. The

Ockey, on October 1, 2021 by guest. Protected copyright. 1962; Nakagome et al, 1965); initial diagnosis was probable pseudohermaphroditism. (Klevit, Mellman, and Eberlein, 1963; Jacobs and At age 4 years, the enlarged clitoris, measuring 3 x 1 Ross, 1966; Jacobs, 1969); translocations (van den cm was totally excised (Fig. lb). A vaginogram per- and formed through the urogenital sinus opening confirmed Berghe, 1965; Federman, Davidoff, Ouellette, the presence of a normal vagina measuring 4 cm in 1967; Nakagome, Smith, and Soukup, 1968; length. The urethra was anatomically normal. Lapa- Schmid, 1969; Biihler, Muller, and Stalder, 1971; rotomy revealed that the uterus (24 x 1 cm) was normally Caspersson et al, 1971; Noel et al, 1971); inversions located with a normal tube and round ligament on the (Jacobs and Ross, 1966; Sparkes, Muller, and right side. The right ovary appeared to be a streak Veomett, 1970); and dicentrics (see Table I). gonad 4 cm long and 8 mm wide. Comparison of 16 patients with dicentric Y chromo- The structures on the left, however, were distinctly somes reveals a wide range of phenotypic, histo- abnormal in appearance. A ligamentous element, gross- ly resembling a fallopian tube, extended from the left cornu of the uterus. Attached to this structure at the Received 3 July 1972. was a x 1 * Present address: Department of Human Genetics, Hadassah level of the internal inguinal ring gonad (1 I cm) Hebrew University Medical Center, Jerusalem, Israel. which had the appearance of a testis with a vas deferens. 74 J Med Genet: first published as 10.1136/jmg.10.1.74 on 1 March 1973. Downloaded from

Human Dicentric Y Chromosomes 75

A,.. ..: a X.. :' :::: :. ^ .! b

FIG. 1. The external genitalia of the proposita. Fig. la-before surgery. Note the clitoral enlargement, scrotalized labia majora, posterior perineal fusion, and a urogenital sinus. Fig. lb-following total .

The entire left gonad and ligamentous structure were cultures of the patient by conventional techniques removed for histological examination. with exposure of the cells to 01 ,tc/ml of tritiated Histologically, the right gonad was diagnosed as a thymidine for the last 41 to 5 hours of culture streak ovary with no follicles; no testicular tissue was (Schmid, 1963). More precise chromosome identi- observed. The left gonad consisted mainly of testicular fication was achieved by fluorescent staining using elements with distinct tubules and a well formed epi- of and didymis paralleled by a well differentiated tube which the method Lin, Uchida, Byrnes (1971). http://jmg.bmj.com/ had a fimbriated end. Near the epididymis was an adrenal nest, consisting of well encapsulated trabecules Results of vacuolated adrenal cortical cells. However, one The X- patterns of the parents were small segment of ovarian stroma within the left gonad compatible with the phenotypic sex; however, the suggested an ovotestis. proposita showed a chromatin negative buccal The patient's development and health to the present smear. The of the parents were mor- are normal. Her linear growth has progressed along the phologically and numerically normal. The father 10th centile but intellectually she is in the dull nor- a Y chromosome smaller than the mal range. At age 11 years, the patient manifests no possessed slightly on October 1, 2021 by guest. Protected copyright. obvious phenotypical stigmata of Turner's syndrome members of group G (21-22) (Fig. 2b). other then mutiple naevi, and her external genitalia are The patient's chromosomes revealed two stem those of a normal prepubertal girl. lines of cells: one with 45 chromosomes, lacking a member of the C group and the other with 46 chromosomes and a morphologically abnormal Cytogenetic Studies element (Fig. 2a). This marker chromosome was X-chromatin determination from buccal smears similar in size to a member of group E (16-18) and was performed on the proposita and her parents possessed two obvious in close proxi- using cresyl echt violet staining. Chromosome pre- mity to each other (dicentric). Of 100 leucocyte parations from cultures of phytohaemagglutinin metaphases studied, 52% contained 46 chromo- stimulated peripheral lymphocytes were made somes with marker, the remainder being cells with following a modification of the technique of Moor- 45 chromosomes. In skin fibroblasts, 28% of the head et al (1960). Fibroblasts derived from a skin cells had 46 chromosomes (with the marker) and biopsy obtained at laparotomy were also examined. 72% had 45 chromosomes. The X-chromatin Autoradiography was performed on lymphocyte negative buccal smear suggested that the missing J Med Genet: first published as 10.1136/jmg.10.1.74 on 1 March 1973. Downloaded from 76 Cohen, MacGillivray, Capraro, and Aceto

,.- K L ..... a, :.:. s Ga . ...i.

*: Sw , .. FX S. b .8 e . -.^ 19-20 21 -22 y

FIG. 2. Partial karyotypes of (a) the proposita showing dicentric Y chromosome and its fluorescent pattern and (b) her father showing small Y chromosome. Note the smaller than normal fluorescent regions in the Y chromosome of both individuals.

chromosome of group C, in the cells with 45 chro- dicentric following II and the reduction of mosomes, was an . the . (2) By a break in either arm of the Autoradiographic analysis demonstrated that the Y followed by sister-strand reunion leading to dicentric marker was indeed late replicating, but duplication-deficiency chromosomes of short or more definitive identification came from fluorescent long arm material, depending on the location of the studies. The dicentric chromosome showed a breaks. (3) By breaks in either arm of the two Y brightly fluorescent area, characteristic of a Y chromosomes in an XYY individual, followed by ex- chromosome (Fig. 2a), at each end. The brightly change. The most likely mechanism for the origin fluorescent regions were greatly reduced in size of the dicentric Y is either alternative 1 or 2. The when compared with the more commonly observed fact that all but one of the patients thus far report- human Y chromosome. This observation is ed are mosaics, each possessing an 45,X cell line, understandable following fluorescence ofthe father's would suggest a post-zygotic origin of the dicentric

small Y which also exhibited only a small fluorescent Y. However, since this particular abnormality may http://jmg.bmj.com/ distal portion (Fig. 2b). Therefore, the karyotype be unstable and therefore selected against, mosaic- of the patient is interpreted as 45,X/46,X,dic(Yq). ism alone should not be used as a criterion for tem- poral aetiology and a distinction between alternatives Discussion 1 and 2 cannot readily be made. Dicentric chromosomes are generally considered The apparent morphological similarity of many of unstable elements since improper alignment of two the human dicentric Ys may be due to a specific centromeres on the metaphase spindle might lead to location(s) on the Y chromosome which might be the formation of a bridge during anaphase. None- highly vulnerable to breakage. In most cases, the on October 1, 2021 by guest. Protected copyright. theless, some dicentrics do persist and replicate original breakage event in the Yq dicentrics must normally (Darlington and Wiley, 1953) since the occur in the proximal region of the short arm, since proximity of the two centromeres is such that they breaks in the proximal region of the long arm would may behave as monocentric elements (Sears and lead to a dic (Yp) (Starkman and Jaffe, 1967). The Camera, 1952). Dicentric chromosomes are per- more distal the break in either arm, the greater will haps the most frequently encountered example of be the distance between centromeres, and those structural rearrangements of the Y chromosome and breaks beyond a critical distance from the centro- 16 such cases have been reported (Table I). In mere might lead to structural rearrangements which marked contrast, dicentric are extremely may be incapable of undergoing mitosis. There- rare. fore, by selection, the long arm dicentric Ys as a Dicentric Y chromosome formation may occur in group and the short arm dicentric Ys as a group three alternative ways. (1) By a break in the short should appear relatively morphologically similar. arm of the Y followed by reunion of the proximal The mosaicism observed in the patients in Table I ends of the in meiosis I, resulting in a could have arisen by either a prezygotic or a post- J Med Genet: first published as 10.1136/jmg.10.1.74 on 1 March 1973. Downloaded from Human Dicentric Y Chromosomes 77 TABLE I PATIENTS POSSESSING DICENTRIC Y CHROMOSOMES

Phenotype Ascertainment Karyotype eal Reference(s) Female Turner's syndrome X/X,dic(Y) Infantile female Bilateral streaks Angell and Polani (cited by McIlree et al, 1966) Female Tumer's syndrome X/X,dic(Y) Infantile female Angell and Polani (cited by Mcllree et al, 1966) Ambiguous genitalia X/X,dic(Yq) Ambiguous Testicular tissue Jacobs (cited by McIlree et al, 1966) Male Azoospermia X/X,dic(Yq) Normal male Mcllree et al (1966) Female Turner's syndrome X/X,dic(Yp) Infantile female Ovarian stroma Starkman and Jaffe (1967) Female Turner's syndrome X/X,dic(Yp) Infantile female Ovarian stroma Starkman and Jaffe (1967) I ~~~~~(right) fibrous streak (left) I______Male _Hypospadias;_testiscryptorchidism X/X,dic(Yq)/XYq - Male Undifferentiated Boschetti et al (1968) Male Hypospadias X/X,dic(Yq) Male Streak (left); Ferrier et al (1968) testis (right) Male Ambiguous genitalia X/Xdic,(Yq) Ambiguous Testiculartissue Yunis (1965) Male Ambiguous genitalia X/XY/XX/X,dic(Yq)/ Ambiguous Testicular tissue Jalbert et al (1969) XX,dic(Yq) Inneme Ba lsa;___l(9 Female Turner's syndrome X/X,dic(Yq) Infantile female Bilateral streaks; Angell et al (1970) ~~~~~testicular Female Turner's syndrome X/X,dic(Yq) IInfantile female Bilateral streaks Angell et al (1970) Female Turner's syndrome X/X,dic(Yp) Infantile female Angell et a! (1970) Male Ambiguous genitalia X/X,dic(Yq)/XY,dic Ambiguous Ovotestis Ying and Ives (1971) (Yq)/XY/X,dic (Yq)dic(Yq) Female Turner's syndrome X,dic(Yq) Female Streak ovaries; Armendares et al (1972) FemaleAmbiguous genitalia [X/Xgdic(Y~)Ambiguous ovarian stroma Female lAmbiguous genitalia |X/X,dic(Yq) |Ambiguous Ovotestis Present case zygotic event. If, during meiosis the dicentric were Turner's syndrome. However, the cytogenetic and formed and non-disjunction occurred at some stage histological evidence strongly suggests mixed http://jmg.bmj.com/ following fertilization, mosaics with different pro- gonadal dysgenesis. Of the 16 patients described portions ofthe resultant cell lines would be observed. in Table I, nine have been classified as female and However, another possible mechanism which does six as male (one unclassified). They manifest a not involve non-disjunction exists. If during the wide spectrum of phenotypic variation, being ascer- first zygotic division, the dicentric Y is formed, it will tained due to clinical manifestations of Turner's behave as an attached Y chromosome after replica- syndrome, ambiguous genitalia, hypospadias, and tion. Therefore, following mitosis two cell lines azoospermia. Similar variation occurs in the ap- (X/X,dic[Y]) will occur. This mechanism will pearance of the external genitalia, which range from on October 1, 2021 by guest. Protected copyright. explain most of the observed cases. However, the normal male or infantile female to ambiguous cases of Jalbert et al (1969) and Ying and Ives genitalia of varying degrees. Histological examina- (1971) must have undergone such a process later in tion of the gonads of these patients exhibits multiple embryonic development since multiple cell lines combinations of tissue, such as undifferentiated exist, one of which retains a normal Y chromosome. ovarian streaks, ovotestis, and frank testicular These two cases, of necessity, also involve non- architecture but without evidence of spermato- disjunction. The non-mosaic case of Armendares genesis. It is therefore obvious that, although all et al (1972) most likely represents a prezygotic event, the patients possess a dicentric Y chromosome, a resulting in dicentric formation before the second unique phenotype cannot be ascribed to this chro- meiotic division, and fertilization by a sperm bearing mosomal abnormality. a dicentric Y chromosome without subsequent The dicentric Y chromosome is, obviously, not non-disjunction. identical in all patients. Most cases involve the The patient described in this report does not ex- duplication of predominantly long arm material hibit the phenotype commonly associated with (dic[Yq]), while three patients possess a duplication J Med Genet: first published as 10.1136/jmg.10.1.74 on 1 March 1973. Downloaded from 78 Cohen, MacGillivray, Capraro, and Aceto primarily ofthe short arm (dic[Yp]). It is interesting J. M. (1972). A dicentric Y chromosome without evidence of sex histological evidence of testicular material chromosomal mosaicism, 46,XYq dic, in a patient with features of that was Turner's syndrome. Journal of Medical Genetics, 9,96-100. present in almost all cases of dic(Yq), but in none of Berghe, H. van den, Steeno, O., Verresen, H., and Moor, P. de the dic(Yp) individuals, who exhibit only ovarian (1965). Hypogonadism associate with chromosomal break in No. 2 translocation presumably on the Y chromosome. stroma (see Table I). This finding, perhaps, sug- Journal of Clinical Endocrinology and Metabolism, 25, 1246-1250. gests that the determinants for testicular develop- Bishop, A., Blank, C. E., and Hunter, H. (1962). Heritable variation ment in the length of the Y chromosome. Lancet, 2, 18-20. may reside in the long arm of the Y chromo- Borgaonkar, D. S., McKusick, V. A., Herr, H. M., de los Cabos, L., some which does not agree with the suggestion of and Yoder, 0. C. (1969). Constancy of the length of human Y male determining genes on the short arm of the Y chromosome. Annaks de Genetique, 12, 262-264. Boschetti, R., Gilbertas, A., Noel, B., and Quack, Bernadette (1968). chromosome (Ferguson-Smith, 1965; Jacob and Pseudohermaphrodisme masculin et mosaique 45,X/46,XY dic/ Ross, 1966; McIlree et al, 1966). However, addi- 46,XXq--. Annales de Genitique, 11, 62-65. Biihler, E. M., Muller, H., and Staider, G. R. (1971). A strongly tional evidence that the long arm of the Y chromo- fluorescing abnormal chromosome in a malformed child. Human- some may also contain genes for testicular develop- genetik, 12, 64-66. ment exists et Caspersson, T., Hult6n, M., Jonasson, J., Lindsten, J., Therkelsen, (Federman al, 1967; Sarto, Opitz, A., and Zech, L. (1971). Translocations causing non-fluorescent and Inhorn, 1969). Even among the cases of Yq Y chromosomes in human XO/XY mosaics. Hereditas, Genetiskt dicentrics, although the marker chromosomes may Arkiv, 68, 317-324. Chapelle, A. de la, Hortling, H., Edgren, J., and Kaariainen, R. be morphologically similar, the sites of breakage and (1963). Evidence for existence of heritable large Y chromo- reunion may not be exactly the same. Therefore somes unassociated with developmental disorder. A cyto- genetical and clinical study of 4 males with hypogonadism, one the presence or absence of given genes depends di- with mongolism, and their relatives. Hereditas, Genetiskt Arkiv, rectly upon the point of breakage. Even though a 50, 351-360. dic(Yq) might be present, the genes necessary for Cohen, M. M., Shaw, M. W., and MacCluer, J. W. (1966). Racial differences in the length of the human Y chromosome. Cyto- testicular development may be lacking, due to the genetics, 5, 34-52. specific location of the break. Since testicular Conen, P. E., Bailey, J. D., Allemang, W. H., Thompson, D. W., and Ezrin, C. (1961). A probable partial of the Y chro- tissue might be absent, such patients might resemble mosome in an intersex patient. Lancet, 2, 294-295. females according to the studies of Jost (1947). A Darlington, C. D. and Wylie, A. P. (1953). A dicentric cycle in case in point is patient No. 2 described by Angell, Narcissus. Heredity, 6 (supplement) pp. 197-213. Federman, D. D., Davidoff, F. M., and Ouellette, E. (1967). Giannelli, and Polani (1970). Presumptive Y/D translocation in mixed gonadal dysgenesis. Finally, the fact that all cases of Y dicentrics, with Journal of Medical Genetics, 4, 36-40. Ferguson-Smith, M. A. (1965). Karyotype-phenotype correlations the exception of the one reported by Armendares in gonadal dysgenesis and their bearing on the pathogenesis of et al (1972), are mosaic individuals must be con- malformations. Journal of Medical Genetics, 2,142-155. indi- Ferrier, P. E., Ferrier, S. A., and Bill, A. H. (1968). A male pseudo- sidered. Since mosaicism most frequently hermaphrodite with a dicentric Y chromosome. Humangenetik, cates a postzygotic event, the precise stage at which 6, 131-141. the non-disjunction might occur would have an Gripenberg, U. (1964). Size variation and orientation of the human Y chromosome. Chromosoma, 15, 618-629. http://jmg.bmj.com/ important bearing as to the phenotype ofthe patient. Jacobs, P. A. (1969). Structural abnormalities of the sex chromo- If the Y chromosome were present during the pro- some. British Medical Bulletin, 25, 94-98. per ontologic period of gonadal development, male Jacobs, P. A. and Ross, E. J. (1966). Structural abnormalities of the Y chromosome in man. Nature, 210, 352-354. structures might be present. If, however, the non- Jalbert, P., Convert, A., Mouriquand, C., and Malka, J. (1969). A disjunction had occurred before this time so that propos d'une observation d'Y dicentrique chez un pseudoherma- phrodite masculin avec mosaique gonosomale complexe. Annales a 45,X constitution existed in the critical cells of the de Genetique, 12,253-258. gonadal anlage, such individuals would probably Jost, A. (1947). Recherches sur la differenciation sexuelle de l'em- bryon de lapin. Archives d'Anatomie Microscopique et de Morpho- exhibit manifestations of Turner's syndrome. The logie Explrimentale, 36, 151-286. on October 1, 2021 by guest. Protected copyright. embryonic timing of such events, therefore, may Klevit, H. D., Mellman, W. J., and Eberlein, W. R. (1963). Triple also influence the phenotypic variability observed. mosaicism with an derived from partially deleted Yin a male pseudohermaphrodite. Pediatrics, 32,56-62. Lin, C. C., Uchida, I. A., and Byrnes, E. (1971). A suggestion for We thank Drs H. Jockin and J. Fisher for the histo- the nomenclature of the fluorescent banding patterns in human logical studies; Pamela Borchert, Laurie Quinn, Geri metaphase chromosomes. Canadian Journal of Genetics and Krypel, Terry Hartnett, and Claudia Hastings for techni- Cytology, 13, 361-363. cal assistance. Additionally, we are indepted to Drs J. Makino, S., Sasaki, M. S., Yamada, K., and Kujii, T. (1963). A Wahrman and R. G. Davidson for helpful discussion and long Y chromosome in man. Chromosoma, 14, 154-161. critical reading of the manuscript. The work was McIlree, M. E., Price, W. H., Court Brown, W. M., Tulloch, W. S., supported in part by a grant from the US Department of Newsan, J. E., and Maclean, N. (1966). 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