Cancer Genetics and Cytogenetics 183 (2008) 114e116

Short communication

Testicular tumor in an XXY dog

Nicola Reimann-Berga,b, Hugo Murua Escobara,b, Ingo Nolteb, Jorn Bullerdieka,b,*aCenter for Human Genetics, University of Bremen, Leobener Str. ZHG, 28359 Bremen, Germany

bSmall Animal Clinic, University of Veterinary Medicine Hanover, Bischofsholer Damm 15, 30173 Hanover, Germany

Received 8 January 2008; received in revised form 6 February 2008; accepted 15 February 2008

Abstract Klinefelter syndrome has been described in various species in addition to humans, including cat, pig,horse, and dog. It is associated with low levels of male hormones, sterility, breast enlargement, andsmall testes. Patients with Klinefelter syndrome have a higher risk for several malignancies. Know-ledge about genetic disorders of the dog is comparatively sparse. This is mainly due to the difficultcanine karyotypic pattern. We present the case of a canine patient with clinically and cytogeneticallyconfirmed Klinefelter syndrome who developed a testicular tumor at a very early age. Testicular tu-mors are common in dogs, normally affecting elderly patients (median age, O9 years). In the presentcase, however, the dog was only 5 years old, allowing the conclusion that the XXY constitution mayhave promoted the early onset of testicular tumor disease. � 2008 Elsevier Inc. All rights reserved.

1. Introduction

Klinefelter syndrome is a genetic disorder of male sex-ual differentiation characterized by an XXY karyotype orsimilar karyotypic deviations including mosaicism. It is of-ten associated with a higher risk for several types of malig-nancies, including mediastinal germ cell neoplasms [1,2],male breast cancer [3], and eventually hematological ma-lignancies [4]. The sex chromosome constitution XXY iswell know in humans [5,6], but it has also been describedfor some domestic animals, such as cat [7,8], pig [9,10],horse [11], and dog [12e15]. Most of the dogs describedin earlier reports exhibited a 78,XY/79,XXY mosaicism.

Here, we present the case of a dog with a constitutionalXXY karyotype (a phenotypically and cytogenetically wellconfirmed Klinefelter syndrome) associated with a testiculartumor. We obtained this result within a project on caninegenetics, which has as one focus the cytogenetic investiga-tion of canine tumors. To our knowledge, there are no pre-vious reports of an association between a tumor disease andKlinefelter syndrome in dogs.

2. Materials and methods

2.1. Clinical examination

The dog, a West Highland White Terrier, age 5 years,was presented at the veterinary hospital with a large

* Corresponding author. Tel.: þ49 421 218 4239; fax: þ49 421 218

4239.

E-mail address: bullerd@uni-bremen.de (J. Bullerdiek).

0165-4608/08/$ e see front matter � 2008 Elsevier Inc. All rights reserved.

doi:10.1016/j.cancergencyto.2008.02.009

testicular tumor. The tumor was surgically removed andhistologically analyzed. X-ray examinations were per-formed and the hormone status was determined.

2.2. Cell culture

A small piece of the tumor sample was transferred intosterile Hank’s solution and minced for cell culture intosmall pieces followed by a collagenase treatment. After3e6 hours, the dissociated cells were transferred into sterileflasks containing 5 mL Medium 199, supplemented with20% fetal bovine serum and 2% penicillin-streptomycin.The cultures were incubated in 5% CO2 air at 37�C for 5days. Colcemid was added at a final concentration of 0.1mg/mL for 2 hours before harvesting. The preparation ofcell cultures for chromosome analysis followed routinemethods [16].

Heparinized blood was collected for in vitro cultivationand chromosome preparation, and 1 ml blood was set upin 10 mL medium. After incubation at 37�C for 86 hours,Colcemid was added at a final concentration of 0.1 mg/mLfor 1.5 hours. The cells were then centrifuged and the pelletwas treated with 0.05 mol/L KCl at 37�C for 25 minutes. Af-ter centrifugation the cells were fixed with 3:1 methanoleglacial acetic acid.

2.3. GTG-banding

The cell suspension was dropped onto ice-cold slides,which were then allowed to dry for 3 days before GTG-

115N. Reimann-Berg et al. / Cancer Genetics and Cytogenetics 183 (2008) 114e116

banding was performed according to a modification [17] ofthe protocol described by Seabright [18].

2.4. Karyotyping

Results were processed and recorded with the PowerGene karyotyping system (PSI, Halladale, UK). The caninekaryotype description followed the nomenclature proposedby Reimann et al. [19].

3. Results

X-ray examination of the terrier revealed characteristicclinical features of a Klinefelter syndrome: eunuchoidalhigh stature and characteristic rugae of the dermis and hy-podermis (Fig. 1). The level of testosterone was 2.04 ng/mLand that of progesterone was 0.49 ng/mL. Compared withthe standard level (O2.5 ng/mL to 8.5 ng/mL), the testos-terone level was low, whereas the progesterone level waswithin normal range (standard level, !0.5 ng/mL).

Histological examination of the testicular tumor re-vealed a Sertoli cell tumor.

Cell culture of the tumor sample resulted in cells grow-ing well and with a moderate mitotic rate. For cytogeneticpreparation, the cells were harvested in the first passage.Karyotyping of 10 metaphases revealed a constitutional79,XXY karyotype (Fig. 2A).

Cytogenetic preparation of the leukocyte cultures re-sulted in a relatively high mitotic rate. For chromosomeanalyses, 10 metaphases were fully karyotyped. Again, allmetaphases revealed a constitutional 79,XXY karyotype(Fig. 2B).

Fig. 1. X-ray image of a dog with a constitutional XXY karyotype, show-

ing an eunuchoidal high stature and characteristic rugae of the dermis and

hypodermis.

4. Discussion

Klinefelter syndrome is the most common sex chromo-some disorder, affecting 1 in 500 men. It is associated withseverely impaired spermatogenesis and hypotestosterone-mia, and is manifested by eunuchoidal body habitus, gy-necomastia, and very small testes [20]. Humans withKlinefelter syndrome are at greater risk of developing tes-ticular cancer [21].

There is only sparse knowledge about the incidence ofchromosomal anomalies in the general dog population. Thislack of information is due mainly to the difficult canine kar-yotypic pattern, which consists of 76 acrocentric autosomesvery similar in shape and size and the metacentric sex chro-mosomes [19]. Nonetheless, cytogenetic investigations indogs could be of great value, especially for breeders dealingwith fertility problems within their pedigrees, for veterinar-ians, and for dog owners.

Fig. 2. (A) 79,XXY karyogram of the canine testicular tumor. (B) 79,XXY

karyotype of the canine leukocytes.

116 N. Reimann-Berg et al. / Cancer Genetics and Cytogenetics 183 (2008) 114e116

The cytogenetic studies performed in our lab, to date in-volving O250 dogs with a male karyotype, have revealeda 79,XXY karyotype only in this one case. X-ray imagingindicates that the terrier’s phenotype, with its eunuchoidalhigh stature and characteristic rugae of the dermis and hy-podermis, is comparable to observations described for menwith Klinefelter syndrome [22].

Testicular tumors are the second most common tumor ofthe male dog. These tumors are more common in the dogthan in any other species, including humans. Sertoli cell tu-mors, seminomas, and interstitial tumors are the most com-mon histological types, occurring with approximately equalfrequency. These tumors normally occur at an age of O9years [23]. In the present case, however, the dog was only5 years of age, which is half as old as the geriatric dogs nor-mally affected by testicular tumors, allowing the conclusionthat an XXY constitution may promote the early onset ofa testicular tumor disease.

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