Occurrence of double aneuploidy in live born is comparatively rare phenomenon inhuman population as compared to higher percentage in spontaneous abortions (Cyril et al., 2005; Karaman and Kabolar, 2008). The patients with double aneuploidy may have manifestations of both chromosomal abnormalities. Further studies on the incidence of an XXY chromosome pattern among patients with Down syndrome have revealed that double aneuploidy might be more frequent than multiplying the frequencies of individual aneuploidies (Mikkelesen et al., 1976; Ford et al., 1959).

The patients with double aneuploidy may have the manifestations of both chromosomal abnormalities. Double aneuploidy leading to trisomy and/or monosomy of 2 different chromosomes arise because of 2 meiotic non-disjunctional events (Eid et al., 2009).

Kovaleva and Mutton (2005) have identified 52 live born cases along 13 prenatal cases and suggested that the frequency of all non-mosaic double aneuploidies except 48,XXY, +21 are lower than expected due to strong intrauterine selection against such pregnancies.

The clinical features of a 12-month old boy who exhibited karyotype 48,XXY, +21 have been described in this paper.

1 Case history

A 12-month old male boy was referred to our laboratory for chromosome analysisbecause clinical features were suggestive of Down syndrome. The age of the mother was 27 and father was 30 years at the time of child birth. The physical examinations of patient presents typical features of Down syndrome with flat profile, mongoloid slant of eyes, flat nasal bridges, low set and malformed ears, short neck, protruding tongue and open mouth. The clinical features of Klinfelter syndrome were not prominent except very small testes and absence of hair on the chest.

2 Method

Blood sample was collected from patient after obtaining informed consent. Chromosome preparations obtained from PHA-stimulated peripheral blood cultures, were subjected to GTG banding. Total of 50 metaphases were scored and karyotype was prepared according to (ISCN, 2009) The automatic scanning system (Axiomerger Z₂–Carl-Zeiss) and karyotyping software (IKAROS, Germany) were used to make karyotypes. The karyotype of child was found to be 48,XXY, +21 (Figure 1) with no evidence of mosaicism. Parental karyotype was not studied as blood was not available.

Figure 1 Karyotype showing 3 copies of chromosome 21, 2 copies of X and 1 copy of Y indicative of double aneuploidy

3 Discussion
We report a case of double aneuploidy consisting of trisomy 21 and XXY. Thepatient showed typical clinical manifestations of Down syndrome; which is consistent with other published reports (Karaman and Kabolar, 2008; Eid et al., 2009; Kovaleva and Mutton, (2005).The real causes of aneuploidies are not well understood, meiotic non-disjunction hasbeen suggested as most frequent cause of chromosomal abnormalities. Normally 50% of XXY cases arise from an error in paternal meiosis – I, and remaining in maternal meiosis I or II. On the other hand, trisomy-21 can originate in either at the divisions in both parents.

Shu X., Zou C., and Shen Z., 2013, Double Aneuploidy 48,XXY, +21 associated with a congenital heart defects in a neonatal, Balkon J. Med. Genet., 16: 89-90
http://dx.doi.org/10.2478/bjmg-2013-0038