# Double deletion of a chromosome 21 inserted in a chromosome 22 in an azoospermic patient

Valentine Marquet, Dominique Bourgeois, Philippe de Mas, Laurence Bouneau, Adeline Vigouroux-castera, Romain Molignier, Patrick Calvas

► To cite this version:

Valentine Marquet, Dominique Bourgeois, Philippe de Mas, Laurence Bouneau, Adeline Vigouroux-castera, et al.. Double deletion of a chromosome 21 inserted in a chromosome 22 in an azoospermic patient. Clinical Case Reports, 2015, 3 (9), pp.757-761. 10.1002/ccr3.313. hal-03482500

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## CASE REPORT

# Double deletion of a chromosome 21 inserted in a chromosome 22 in an azoospermic patient

Valentine Marquet<fnref n="1" />, Dominique Bourgeois<fnref n="1" />, Philippe De Mas<fnref n="2" />, Laurence Bouneau<fnref n="1" />, Adeline Vigouroux-Castera<fnref n="1" />, Romain Molignier<fnref n="2" /> & Patrick Calvas<fnref n="1" />

**Correspondence**

Dominique Bourgeois, Service de Génétique Médical, Centre Hospitalier Universitaire Purpan, Toulouse, France.

Tel: +033567690397; Fax: +033567690403;

E-mail: bourgeois.d@chu-tonouse.fr

**Funding Information**

No sources of funding were declared for this study.

Received: 3 December 2014; Revised: 27

March 2015; Accepted: 12 May 2015

Clinical Case Reports 2015; 3(9): 757-761

doi: 10.1002/ccr3.313

**Key Clinical Message**

We report on a phenotypically normal 41-year-old azoospermic man with a 45 chromosomes karyotype including one normal chromosome 21, one normal chromosome 22, and a der(22)ins(22;21). Array CGH showed a 1.8 Mb terminal deletion of bands 21pter to 21q21.1 and a 341 kb terminal deletion on band 21q22.3.

**Keywords**

Azoospermia, chromosome 21, chromosome 22, deletion, chromosome, insertion, karyotype, partial monosomy 21.

## Introduction

Several 21q partial monosomies have been reported in the literature, presenting phenotypes with highly variable severity and features, depending on size, position of the deletion, and associated chromosomal rearrangement. Some authors have delineated critical regions along the long arm of chromosome 21 according to the severity of the phenotype associated with the deletion. Many patients with 21q deletion and a very mild phenotype have been described, in particular paracentromeric and subtelomeric 21q deletions [3, 5, 18]. However, to our knowledge only one case of chromosome 21 deletion associated with a chromosome 21 insertion into chromosome 22 has been described to date, in a family whose proband had a partial trisomy 21 and other members were carriers of the recombinant chromosome in a 45 chromosome karyotype [2]. We report here a patient carrying two deletions on the long arm of a chromosome 21 inserted into a chromosome 22, and whose only phenotype was azoospermia.

## Materials and Methods

### Clinical description

Our patient was referred to the geneticist for infertility due to azoospermia. This 41-year-old man has normal intelligence: he is married and has a normal social and professional life. He does not show any particular sign or symptom besides infertility, and notably no sign of hypogonadism. He is the first of three children, born to non-related parents. His brother and sister are both healthy with normal karyotypes. His sister is the mother of two healthy boys. His father died of a stroke at the age of 39 and his mother, who was alcoholic, died at the age of 65. No genetic analysis is available for them. The patient also has a healthy first degree paternal cousin.

### Cytogenetic analysis

Peripheral blood from the patient was prepared according to the standard cytogenetic procedures and metaphases

<footnote n="1">¹Service de Génétique Médical, Centre Hospitalier Universitaire Purpan, Toulouse, France</footnote>

<footnote n="2">²Laboratoire de Biologie Clinique, Clinique Saint Jean Languedoc, Toulouse, France</footnote>
were analyzed by R-banding and G-banding. A 550-band
resolution karyotype was obtained.

Array-CGH

Array-CGH was performed on a CytoChip ISCA 4x44K
v1.0 (BlueGnome Ltd, Cambridge, U.K.) pangenomic oli-
gonucleotide array, according to the standard procedures
with a quatuor method (two "color swap" hybridizations
with cyanine 3 and 5 staining). BlueFuse MULTI (BlueG-
nome Ltd) was used for informatic analysis of the results.
Medical analysis was performed with Cartagenia (Leuven,
Belgique) and results were compared with the data in
DGV (Database of Genomic Variants) for benign CNVs
(Copy Number Variants), to DECIPHER (Wellcome
Trust Sanger Institute, Cambridge, U.K.) and ISCA (The
International Standards for Cytogenomic Arrays Consor-
tium) for deleterious CNVs. We used the human genome
assembly hg19 (GRCh37) for all molecular analysis (En-
sembl Genome Browser).

Fluorescent in situ hybridization

Fluorescent in situ hybridization (FISH) was performed
according to a standard protocol with an overnight
hybridization followed by a SSC solution wash. To con-
firm the karyotype anomalies, D21S1446 and D22S105
subtelomeric probes of chromosomes 21 and 22, respec-
tively (Kreatech, Amsterdam, the Netherlands) were used.
Array-CGH anomalies were confirmed and structurally
characterized using several probes: wcp (whole chromo-
some painting) of chromosomes 21 (Spectrum Red) and
22 (Spectrum Green) probes (Metasystems, Altlusseim
Germany), centromeric 13/21 and 14/22 probes (Kreatech
Diagnostics), and Bacterial Artificial Chromosomes
(BACs) probes mapped on chromosome 21: RP1-126N20
(21q11.2), RP11-482O14 (21q21.1), RP11-25F24
(21q21.2), RP11-71A7 (21q22.3), and RP11-323F14
(21q22.3) (BlueGnome, Illumina, Cambridge, U.K.).

<figure><img src="image_2.png" /><figcaption>**Figure 1.** R-banding (A) and G-banding (B) partial karyotype of chromosomes 21, 22, and the derivative chromosome 22 due to the insertion of a segment of 21q.</figcaption></figure>

Results

Fifteen mitoses were analyzed, revealing a 45 chromosome karyotype with one normal chromosome 21, one normal chromosome 22, and a derivative chromosome 22 caused by insertion of a chromosome 21 into a chromosome 22 (Fig. 1).

Array-CGH showed a deletion on each end of chromo-
some 21 (Fig. 2). The proximal one, localized on
21q11.1q21.1 (15,499,877-17,224,547), is 1.7 Mb long and
involves six OMIM genes including one OMIM morbid
gene, LIP1. The distal one is a terminal deletion of
341 kb in 21q22.3 (47,797,296-48,090,288), encompassing
four OMIM genes. Among them, the only OMIM morbid
gene is PCNT. No other CNV on chromosome 22 was
highlighted as previously seen on karyotype.

Fluorescent in situ hybridization analysis confirmed the
deletions and complete inverted insertion of the remain-
ing segment of the inserted chromosome 21. The other
chromosome 21 and 22 are both normal (Fig. 3).

The final karyotype is:

45,XY,-21,der(22)ins(22;21).ish der(22)ins(22;21)(q13.2;q22.3q21.1)(wcp21+,RP11-25F24+,RP11-323F14+)del(21)(pterq21.1)(RP1-126N20-,RP11-482O14-)del(21)(q22.3)(RP11-71A7-)

Discussion

A few years ago, monosomy 21 was thought to be the
only viable autosomic monosomy. However, most of the
reported cases turned out to be partial monosomies
resulting from cryptic translocations or mosaics [4, 8, 10,
12, 15, 20, 22].

The case we report here shows an unusual rearrange-
ment with a deletion of both ends of chromosome 21:
the short arm, the centromere and a 1.7 Mb proximal
segment of 21q are deleted, as well as a 341 kb subtelo-
meric portion of 21q, with only an acentric 21q segment
left. This segment is preserved because of its insertion
into a chromosome 22, leading to a 45 chromosomes
karyotype with an apparent monosomy 21. To our
knowledge, Aviv et al. described the only case of a
familial complex rearrangement with a der(22)t(21;22)
associated with a chromosome 21 pter to q21.2 deletion.
The deleted regions on chromosomes 21 and possibly 22
were not precisely specified by array-CGH analysis. The
carriers were diagnosed because this family included a
child carrying a partial trisomy 21 due to the presence
of two normal chromosomes 21 and the derivative chro-
mosome 22. However, the subjects carrying the rear-
rangement had a more severe phenotype than our
patient, including mild developmental delay, poor social
adjustment, psychiatric and behavioral problems, without
fertility issues. Nevertheless, these phenotypic features
<figure><img src="image_3.png" /><figcaption>**Figure 2.** Array-CGH showing deletions of the proximal and distal ends of chromosome 21, respectively, 1,7 Mb and 341 kb.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>**Figure 3.** (A) D21S1446 (21q telomere), SE13/21 (centromeres of chromosomes 13 and 21), and SHANK3 (22q telomere) FISH probes showing the deletion of a 21q subtelomeric region and the integrity of both 22q subtelomeric regions. (B) Painting wcp 21 (chromosome 21) and wcp 22 (chromosome 22) FISH probes showing the insertion of chromosome 21 into chromosome 22. (c) FISH using a red RP11-25F24 (21q21.2), a green RP11-323F14 (21q22.3) BAC probes, and a red D22S105 probe (22q telomere) showing the inversion of the inserted chromosome 21 segment. Yellow arrow: chromosome 21 inserted in chromosome 22.</figcaption></figure>

may partly be explained by the psychosocial environment.

Chettouh et al. [3] defined five critical regions on the long arm of chromosome 21, responsible for the main

clinical signs associated with 21q monosomies. Subsequently, Lyle et al. [13] suggested another model dividing chromosome 21 in 3 critical regions. Deletions from the centromere to 32.3 Mb (to the beginning of band q22.11)
are associated with a severe phenotype and deletions from 32.3 to 37.1 Mb (q22.11 to beginning of q22.12) with an even more severe phenotype, whereas deletions from approximately 37.1-38.6 Mb (q22.12) to the telomere are associated with a mild phenotype. This classification remains imprecise especially for the first region, because they considered three patients with large deletions spanning from the centromere to bands 21q21.3 or 21q22.11. But other authors have described patients with a proximal deletion upstream of 21q22 without major phenotypic effect. The familial rearrangement with a 21pter→21q21.2 deletion previously described was revealed only after the birth of a partial 21 trisomy carrier [2]. In the same way, subject GMU [3] showed a 45,XX,-21,der(9)t(9;21)(pter;q21) karyotype with a partial monosomy 21 (pter→q21), without any notable phenotypic impact. Finally, patient 3 from Lindstrand et al. [11] had a 14 Mb interstitial deletion at 21q11.1q21.3 and only showed balance and gross motor difficulties at age 5. In fact, the severity of the phenotype described by Lyle et al. in this proximal centromere-32.3 Mb region is probably caused by the deletion of band 21q22 in two out of three patients, corresponding to the description of "monosomy 21q syndrome" [19]. The latest described patient carrying a 21q22 deletion is a 19-month-old child with a global developmental delay, dysmorphic features, and cardiac and neurological malformations [6]. Deletion of the more distal segment of 21q is the most common 21q deletion and is not responsible for severe phenotypes and intellectual deficiency according to the division of chromosome 21 by Lyle et al. [13], in agreement with other described cases. Two patients were reported with a large 21q22.2q22.3 deletion, respectively, approximately 7.9 and 4.7-7.3 Mb, associated with a phenotype including mild intellectual deficit, a few dysmorphic features, epilepsy, marfanoid habitus and, for the latter, isthmic stenosis of the aorta [5]. Four further cases of 21q terminal deletion also had a minimum size of 4.86 Mb, associated with a mild phenotype including mild intellectual deficit and dysmorphic features without any visceral malformation [17].

Infertile men with a chromosome 21 deletion have been previously described. Alkhalaf et al. [1] reported a 24-year-old man with a 46,XY,del(21)(pter→q11.2) who had hypogonadism and azoospermia. Gekas et al. [7] identified a patient with a 46,XY,r(21) karyotype among a cohort of 2196 infertile men, but the ring 21 was not precisely described. We hypothesize that the same mechanism led to the formation of this ring 21 and of the der(22)ins(22;21) of our patient, with a loss of both telomeric extremities of the 21 chromosome followed by a rearrangement in order to stabilize the deleted chromosome. Our patient's azoospermia could be the consequence of the haploinsufficiency, although none of the deleted genes have been involved in spermatogenesis to date. However,

the chromosome rearrangement itself is more likely to be responsible for a chromosome missegregation during meiosis, leading to spermatogenesis failure because of the impossibility of producing balanced gametes. According to McKinlay Gardner and Sutherland [14], a chromosome rearrangement, especially when involving an acrocentric chromosome, might disrupt the integrity of the X-Y bivalent and impair the synapsis of homologous segments in the normal and the rearranged chromosomes, leading to disruption of spermatogenesis.

In spite of this particular chromosomal rearrangement with two deletions on chromosome 21, our patient has a normal phenotype, apart from the azoospermia. As previously discussed, the location of the deletions can account for the normal phenotype. The low number of genes involved is another argument. Only 10 OMIM genes are deleted, and among them only two OMIM morbid genes, *LIP1* (609252) and *PCNT* (605925), for which haploinsufficiency is not known to be associated with pathology [16], [21].

In conclusion, we report the first case of a patient carrying a deletion of both extremities of a chromosome 21 and an insertion of this chromosome into a chromosome 22, with no phenotypic consequence other than a secretory azoospermia.

## Conflict of Interest

None declared.

## References

1. Alkhalaf, M., L. Verghese, and N. Muharib. 2002. A cytogenetic study of Kuwaiti couples with infertility and reproductive disorders: short arm deletion of chromosome 21 is associated with male infertility. Ann. Genet. 45:147-149.

2. Aviv, H., C. Lieber, A. Yenamandra, and F. Desposito. 1997. Familial transmission of a deletion of chromosome 21 derived from a translocation between chromosome 21 and an inverted chromosome 22. Am. J. Med. Genet. 70:399-403.

3. Chettouh, Z., M. F. Croquette, B. Delobel, S. Gilgenkrants, C. Leonard, C. Maunoury, et al., et al. 1995. Molecular mapping of 21 features associated with partial monosomy 21: involvement of the APP-SOD1 region. Am. J. Hum. Genet. 57:62-71.

4. Cohen, M. M., and T. I. Putnam. 1972. An translocation in a patient with presumptive "monosomy G". Am. J. Dis. Child. 124:908-910.

5. Ehling, D., I. Kennerknecht, A. Junge, B. Prager, R. Exeler, B. Behre, et al. 2004. Mild phenotype in two unrelated patients with a partial deletion of 21q22.2-q22.3 defined by FISH and molecular studies. Am. J. Med. Genet. Part A. 131:265-272.
6. Fukai, R., Y. Hiraki, G. Nishimura, M. Nakashima, Y. Tsurusaki, H. Saitsu, et al. 2014. A de novo 1.4-Mb deletion at 21q22.11 in a boy with developmental delay. Am. J. Med. Genet. A 164:1021–1028.

7. Gekas, J., F. Thepot, C. Turleau, J. P. Siffroi, J. P. Dadoune, S. Briault, et al. 2001. Chromosomal factors of infertility in candidate couples for ICSI: an equal risk of constitutional aberrations in women and men. Hum. Reprod. 16:82–90.

8. Gill, P., S. Uhrich, C. Disteche, and E. Cheng. 1994. Foetal t(5p;21q) misdiagnosed as monosomy 21: a plea for in situ hybridization studies. Am. J. Med. Genet. 52:416–418.

9. Hertz, B., C. A. Brandt, M. B. Petersen, S. Pedersen, U. König, H. Strømkjaer, et al. 1993. Application of molecular and cytogenetic techniques to the detection of a de novo unbalanced t(11q;21q) in a patient previously diagnosed as having monosomy 21. Clinic Genet. 44:89–94.

10. Ikeuchi, T., I. Kondo, M. Sasaki, Y. Kaneko, and S. Kodama. 1976. Unbalanced 13q/21q translocation: a revised study of the case previously reported as 21-monosomy. Hum. Genet. 33:327–330.

11. Lindstrand, A., H. Malmgren, S. Sahlén, J. Schoumans, A. Nordgren, U. Ergander, et al. 2010. Detailed molecular and clinical characterization of three patients with 21q deletions. Clin. Genet. 77:145–154.

12. Lopez-Pajares, I., A. Martin-Ancel, P. Cabello, A. Delicado, A. Garcia-Alix, and C. San Roman. 1993. De novo t (5p;21q) in a patient previously diagnosed as monosomy 21. Clinic Genet. 43:94–97.

13. Lyle, R., F. Béna, S. Gagos, C. Gehrig, G. Lopez, A. Schinzel, et al. 2009. Genotype-phenotype correlations in Down syndrome identified by array CGH in 30 cases of partial trisomy and partial monosomy chromosome 21. Eur. J. Hum. Genet. 17:454–466.

14. McKinlay Gardner, R. J., and G. R. Sutherland. 2004. Gametogenesis and conception, pregnancy loss, and infertility. Pp. 339–360 in R. J. McKinlay Gardner and G. R. Sutherland, eds. Chromosome abnormalities and

genetic counseling, 3rd edition. Univ. Press, Oxford, U.K.

15. Phelan, M. C., C. C. Morton, R. E. Stevenson, R. E. Tanzi, G. D. Stewart, P. C. Watkins, et al. 1988. Molecular and cytogenetic characterization of a de novo t(5p;21q) in a patient previously diagnosed as monosomy 21. Am. J. Hum. Genet. 43:511–519.

16. Rauch, A., C. T. Thiel, D. Schindler, U. Wick, Y. J. Crow, A. B. Ekici, et al. 2008. Mutations in the pericentrin (PCNT) gene cause primordial dwarfism. Science 319:816–819.

17. Roberson, E. D., E. S. Wohler, J. E. Hoover-Fong, E. Lisi, E. L. Stevens, G. H. Thomas, et al. 2011. Genomic analysis of partial 21q monosomies with variable phenotypes. Eur. J. Hum. Genet. 19:235–238.

18. Tinkel-Vernon, H., S. Finkernagel, F. Desposito, C. Pittore, K. Reynolds, and L. Sciorra. 2003. Patient with a deletion of chromosome 21q and minimal phenotype. Am. J. Med. Genet. Part A. 120A:142–143.

19. Valetto, A., A. Orsini, V. Bertini, B. Toschi, A. Bonuccelli, F. Simi, et al. 2012. Molecular cytogenetic characterization of an interstitial deletion of chromosome 21 (21q22.13q22.3) in a patient with dysmorphic features, intellectual disability and severe generalized epilepsy. Eur. J. Med. Genet. 55:362–366.

20. Viljoen, D. L., F. Speleman, R. Smart, N. Van Roy, J. du Toit, and J. Leroy. 1992. Putative monosomy 21 in two patients: clinical findings and investigation using fluorescence in situ hybridization. Clinic Genet. 43:105–109.

21. Wen, X. Y., R. A. Hegele, J. Wang, D. Y. Wang, J. Cheung, M. Wilson, et al. 2003. Identification of a novel lipase gene mutated in lpd mice with hypertriglyceridemia and associated with dyslipidemia in humans. Hum. Molec. Genet. 12:1131–1143.

22. Yao, X. L., and E. C. Jenkins. 1994. Translocation 4p;21q identified by FISH in a case previously described as "presumptive monosomy 21". Am. J. Med. Genet. 52:491–492.