ISRAEL JOURNAL OF
VETERINARY MEDICINE
MOSAICISM 78,XX/77,XO IN A BULL TERRIER OF
SMALL STATURE
Vol. 57 (2) 2002
B. Goldschmidt, K. El Jaick, L. M. Souza, C. L. C. Abreu and T. G. Pinho,
Veterinary School, Fluminense Federal University, Vital Brazil Street, n0 64,
Niter—i, R J, Brazil
Abstract
A 78,XX/77,XO complement was detected in a one-year-old Bull Terrier, phenotypical female,
examined because of small stature. The bitch was smaller than its littermates. Other somatic
abnormalities associated with the XO karyotype in other species were not present. The estrus and the
progesterone level were compatible with presence of a corpus luteum.
Introduction
The chromosome basis of Turner’s Syndrome was estabilished in the human species in
1959 when the first patient who was studied cytogenetically had shown a 45,X chromosome
constitution (1).
Among liveborn human females with Turner’s Syndrome, about 50% have apparently a
non-mosaic 45,X constitution, while the remainder have a second cell line containing two sex
chromosomes which may be of X or Y chromosome origin (2).
The XO genotype has been reported in many species associated with ovarian dysgenesis (37). In dogs only two cases of XO chromosome constitution have been reported (8,9). The first
was a 6-month-old female Doberman Pinscher that had never shown signs of estrus, was of
small stature, had an enlarged clitoris and excessive skin in the ventrum of the neck. The
second related case was a 9-month-old miniature American Eskimo bitch with a history of
persistent proestrus. The bitch was small for her age and had a slightly sparse coat.
Case Report
A one-year-old female Bull Terrier (Fig. 1) was referred to the clinical service of the Fluminense
Veterinary School to investigate its short stature.
Heparinized blood was collected for cytogenetic evaluation and lymphocytes were isolated and
cultivated using procedures previously described (10). Fifty cell spreads examined by Giemsa staining
revealed a chromosome complement of 77 leaving one X chromosome in 20% of the cells (Fig. 2). The
remainder had the normal canine female complement of 78,XX chromosomes.
The bitch had skin lesions over all the body and according to the owners, presented two normal heats
since she was six months old. In the second estrus, progesterone level (24,5ng/ml), mesured by the
ELISA method, was compatible with the presence of a corpus luteum indicating that ovulation had
occured. She was mated and a single female pup was born.
Figure 2 - A metaphase showing monosomy of X chromo
Figure 1 - Female bull terrier with small stature
Discussion
Our case represents mosaicism of post-zygotic mitotic origin, where a Turner line originated from a
normal XX karyotype.
The short stature in this dog could be attributed to the XO genotype, since small stature and
hypoplasia of the genital system is commonly reported in animals of other species with monosomy-X.
The progesterone level (24,5 ng/ml) and the birth of only one pup suggest that in this level of
mosaicism the gonads were not completely dysgenetic.
The phenotypic manifestations of X monosomy in human females are due to the absence of the short
arm. The terminal Xp deletions have somatic trait characteristics of the Turner Syndrome, with short
stature whereas function is generally preserved. On other hand, more extensive Xp deletions
lengthening to the proximal region of Xp11 are associated in most cases with a complete Turner
Syndrome phenotype, including gonadal dysgenesis (11).
The proportion of detectable mosaicism is much lower among spontaneous abortions than livebirths
with a XO cell line (12) and it has been suggested that the non-mosaic XO constitution is a pre-natal
lethal condition and that liveborn individuals with Turner’s Syndrome have a second cell line, whether
or not it is demonstrable by conventional cytogenetic techniques (13).
X monosomy in dogs is an extremely rare chromosome aberration. As far as we know, very few
cases have been reported and none of them consisted of mosaicism (8,9).
This bitch had a short stature and low fertility in common with other mammals with an XO
karyotype.
References
1. Ford, C. E., Jones, K. W., Polani, P. E., De Almeida, J. C. And Briggs. J.H.: A Sex chromosome
anomaly in a case of gonadal dysgenesis (Turner’s Syndrome). Lancet i, 711-713, 1959
2. Magenis, R. E., Breg, W. R., Clark, K. A., Hook, E. B., Palmer, C. G., Pasztor, L. M., Summitt, R.
L. and Van Dyke, D.: Distribution of Sex chromosome complements in 651 patients with Turner’s
Syndrome. Am. J. Hum. Genet. 32: 79A, 1980.
3. Sharma, T. And Raman, R.: An XO female in the Indian mole rat. J. Hered. 62: 384-387, 1971.
4. Weiss, G., Weick, R .F., Knobil, E., Wolman, S. R. And Gorstein, F.: An XO anomaly and ovarian
dysgenesis in a Rhesus monkey. Folia Primatol (Basel) 19: 24-27, 1973.
5. Chandley, A. C., Fletcher, J., Rossdale, P.D., Peace, C. K., Ricketts, S. W., MaEnery, R. M., thorne,
J. O., Short, R. V. And Allen, W. R.: Chromosome abnormalities as a cause of infertility in mares. J.
Reprod. Fertil. (Suppl) 23: 337-383, 1975.
6. Long, S. E. and Berepubo, N. A.: A 37 XO chromosome complement in a kitten. J. Small Anim.
Pract. 21: 627-631, 1980.
7. Zartman, D. L., Hinesley, L. L. and Gnalkowski, M. W.: A 53X female sheep (Ovis aires).
Cytogenet. Cell Genet. 30: 54-58, 1981.
8. Smith, F. W., Bouen, L. C., Weber, A. F., Johnston, S. D., Randolph, J. F. and Waters, D.J.: Xchromosomal monosomy (77,XO) in a Doberman Pinscher with gonadal dysgenesis. J. Vet. Intern.
Med. 3: 90-95, 1989.
9. Lšfstedt, R. M., Buoen, L. C., Weber, A. F., Johnston, S. D., Huntington, A. and Concannon, P. W.:
Prolonged proestrus in a bitch with X chromosomal monosomy (77,XO). J. Am. Vet. Med. Assoc.
200(8): 1104-1106, 1992.
10. Moorhead, P. S., Nowell, P. C., Nellman, W. J., Battips, D. M. and Hungerford, D. A.:
Chromosome preparations of leucocytes cultures from human peripheral blood. Exp. Cell Res. 20:
613-616, 1960.
11. Jacobs, P. A., Betts, P. R., Cockwell, A. E., Crolla, J. A., MacKenzie, M. J., Robinson, D. O. And
Youings, S. A.: A cytogenetic and molecular reappraisal of a series of patients with Turner’s
Syndrome. Ann. Hum. Genet.54: 209-223, 1990.
12. Hassold, T., Benham, F. and Leppert, M.: Cytogenetic and molecular analysis of Sexchromosomes monosomy. Am. J. Hum. Genet. 42: 534-541, 1988.
13. Hook, E. B. and Warburton, D.: The distribution of chromosomal genotypes associated with
Turner’s syndrome: livebirth prevalence rates and evidence for diminished fetal mortality and severity
in genotypes associated with sructural X abnormalities or mosaicism. Hum. Genet. 64: 24-27, 1983.