J Med Genet: first published as 10.1136/jmg.7.1.37 on 1 March 1970. Downloaded from Journal of Medical Genetics (1970). 7, 37. A Family with a Large Y Chromosome OMAR S. EL-ALFI From the Unit of Medical Genetics, Sabah Hospital, Kuwait It is generally agreed that the Y chromosome TABLE I shows greater variations in size than other chromo- MAIN CLINICAL FEATURES OF PATIENTS somes (Carr, Barr, and Plunkett, 1961; Bishop, Blank, and Hunter, 1962). In many cases, this 1.1 II.1 II.2 II.3 variability in length is artefactual (De la Chapelle et Age (yr.) 34 6i 5 3j Height (cm.) 185 130 127 107 al., 1963), in others it may only be an elongation Skull circumference (cm.) 55 55 52 52 effect (Wennstrom and De la Carrying angle (± 180) + + + + Chapelle, 1963). External genitalia (large) + + + + Occasionally, however, there is a true addition of Behaviour disorder + + + + + + Mental subnormality - + - + chromosomal material to the Y chromosome, re- EEG abnormalities + + + + sulting either from duplication or from transloca- Serum protein band + + + + Sex chromatin (buccal) - _ _ tion from another chromosome (De la Chapelle et ABO group 0 B A B al., 1963). A review of the cases reported to have a large Y chromosome shows that, so far, there is no uniform (b) All four males showed skeletal overgrowth, as or repeatable clinical pattern (Makino and Takagi, compared to the average stature of the population in the area. The father is 182 cm. in and 1965) that qualifies for the designation 'large Y height, muscular, has copyright. syndrome'. a coarse voice. The three boys are well above the 90th percentile curve of height for children of the same ethnic Family group (Abboud et al., 1957) (Fig. 2). In all four, the Report increase in The height was relatively more in the trunk than present family, living in Kuwait, Arabia, consists in the extremities, resulting in a slightly increased ratio of the two parents (the father 34 years old, working as a of cephalopubic/total height. An additional skeletal barber; the mother 25 years), and three sons, 6+, 5, and feature in the eldest son is a short second metacarpal bone http://jmg.bmj.com/ 3j years old. At the time of preparation of this paper, in both hands. the mother delivered a full-term female with Down's syndrome and cyanotic congenital heart disease; the girl 137* 90pc died within 24 hours of birth (Fig. 1). 132- I 127 5/Opc on September 24, 2021 by guest. Protected 122- II I l-Iw2 w3 4 FIG. 1. Family pedigree. See Table I for main clinical features. 112. IOpc The clinical features (Table I), common to all four males in the family, are as follows. 107 - (a) Behaviour disorder, mildest in the father, with 3211 5- 8 9 1 hyperkinesia in all three sons, together with a destructive tendency and moderate degree of mental subnormality 102 in two of them. All four showed generalized, non- specific, electroencephalographic changes, with question- 97 able paroxysmal abnormality in the older son, but no 3 4 5 6 7 8' 9' 10 history of epileptic fits. Age (years) Received 8 August 1969. FIG. 2. Heights of the three children compared to those of children from the same ethnic group. 37 38 Omar S. El-Alfi J Med Genet: first published as 10.1136/jmg.7.1.37 on 1 March 1970. Downloaded from 11.1 13r.3_~~~ fr- -lE FId3 t I; Sons 1 1 FIG. 3. Acrylamiide gel electrophoresis for sera from the father (I.1), the three sons (II.1, II.2, and II.3), and control (c). (c) The cubital carrying angle is straightened, almost normal sera (H. E. Sutton, 1968, personal communica- 180°, in all four males. tion) (Fig. 3). (d) All four have oversized external genitalia, the youngest boy- 3j years old-has a penis 5 cm. long, with Chromosomal Study a few hairs on the pubic region. The size of the testicles Cultures of peripheral blood leucocytes were pre- is also slightly enlarged in the three sons. Urinary 17- pared from the father, the mother, and the three sons as ketosteroids in the father were 23 mg./24 hours (control well as the newborn girl, using a modified technique 10-20). described elsewhere (El-Alfi, Ragab, and Eassa, 1967). (e) Serum protein electrophoresis (cellulose acetate, Incubation was maintained for 72 hours, followed by 2copyright. barbitone buffer pH 8-6) revealed an extra band im- hours' exposure to colcemid (1 ug./10 ml.), hypotonic mediately following the ,B-globulin, well seen in the treatment, fixation in 1: 3 acetic-methanol, then flaming. father and the three sons, but not in the mother. A An average of 60 metaphases was examined from each study of the sera of the father and the three sons on culture. The mother showed a karyotype of 46,XX, acrylamide gel showed this band to be a strong repre- with no detectable abnormality. The newborn girl's sentation of a weaker band that is sometimes detected in karyotype was 47,XX,G + in all cells examined. The http://jmg.bmj.com/ on September 24, 2021 by guest. Protected FIG. 4. Karyotype of father. J Med Genet: first published as 10.1136/jmg.7.1.37 on 1 March 1970. Downloaded from Family with a Large Y Chromosome 39 FIG. 5. Karyotype of third son. father andithe three sons had a karyotype of 46,XY with segment has no active genes, for there is general a large Y chromosome in all the cells studied (Fig. 4 and agreement that a major part of the normal Y chro- 5). The Y chromosome in all is comparable in length to mosome carries no active genes (Makino et al., copyright. the 13-15 (D) group of chromosomes, and in most of the 1963). metaphases studied the ratio of the length of the Y to the mean length of the D chromosomes ranged between 0 95 On the other hand, the human Y chromosome is, and 1.10. The increase in length of the Y chromosome thought to influence behaviour, stature, cubital appeared to be all in the long arm (centromeric index 11- angle, and male genital development (Jacobs et al., 12%). In a few plates more than one secondary con- 1965; Court Brown, Price, and Jacobs, 1968; striction was suspected on the long arm of the Y, but the Lancet, 1965; Patanelli and Nelson, 1961; Muldal usual pattern, however, in the plates where a distinct and Ockey, 1962). The multiplicity of phenotypes http://jmg.bmj.com/ secondary constriction was seen, was a single secondary among many of the large Y males might thenibe constriction situated within the distal third of the long explained by the different combinations of genes, arm. added to-or lost from-the Y chromosome, Discussion through duplication or translocation (whether from Conclusions drawn by various authors, from some an autosome, or from the X chromosome). 60 cases of large Y chromosome reported in the All four males in the family of the present report literature, point out that the enlargement of the Y have a large Y chromosome, together with a on September 24, 2021 by guest. Protected chromosome is not essentially correlated to uniform clinical picture consisting of behaviour dis- specific abnormal phenotype (Bishop et al., 1962; order, skeletal overgrowth, straight carrying angle, Makino and Takagi, 1965). Large Y chromosomes genital overgrowth, and an abnormal serum protein were reported in normal males (Bender and Gooch, band. It may be assumed that these clinical mani- 1961; Gripenberg, 1964), as well as in males mani- festations are related to the abnormal large Y festing various disorders including multiple con- chromosome that all four males carry. Some of genital malformations (Makino and Takagi, 1965), these manifestations, namely skeletal overgrowth Down's syndrome (Dekaban, Bender, and Econo- and behaviour disorders, are reported in many mos, 1963), hypogonadism (De la Chapelle and 47,XYY males (Jacobs et al., 1965; Court Brown Hortling, 1963), mental retardation (Tonomura and et al., 1968), and could probably be the result, in Ono, 1963), etc. More than one-third of the cases those cases, of the duplication ofthe Y chromosome. reported had a normal phenotype. The large Y This clinical resemblance with 47,XYY cases sug- chromosome in these cases may be explained either gests that the large Y chromosome in the present by an elongation of the chromosome, or by assum- family represents a duplication of a segment of the Y ing that the added or duplicated chromosomal chromosome or possibly a translocation of 2 normal J Med Genet: first published as 10.1136/jmg.7.1.37 on 1 March 1970. Downloaded from 40 Omar S. El-Alfi Y chromosomes in the father, so that effectively A girl with a karyotype 47,XX,G + was born in the father and sons are all XYY. The band seen this family. on serum protein electrophoresis, being a strong representation of a weaker band occasionally de- REFERENCES in normal sera E. Abboud, M. A., El-Alfi, O., Hefny, A., and El-Mazny, A. R. (1957). tected (H. Sutton, 1968, personal An anthropometric study of Arabian school-children. Gazette of communication), might as well be the result of a the Egyptian Paediatric Association, 5, 493-503. dose-effect of a gene carried by the Y chromosome. Bender, M. A., and Gooch, P. C. (1961). An unusually long human Y chromosome. Lancet, 2, 463-464. The birth of a 47,XX,G + girl in this family Bishop, A., Blank, C. E., and Hunter, H. (1962). Heritable variation raises a question whether there is a relation between in the length of the Y chromosome.