Journal of Genetics (2019) 98:77 © Indian Academy of Sciences https://doi.org/10.1007/s12041-019-1120-3 RESEARCH ARTICLE Developmental retardation due to paternal 5q/11q translocation in a Chinese infant: clinical, chromosomal and microarray characterization XIANGYU ZHAO1 , HONGYAN XU1, CHEN ZHAO2 and LIN LI1∗ 1Department of Medical Genetics, Linyi People’s Hospital, Linyi 276003, Shandong, People’s Republic of China 2Department of Neurology, Weifang People’s Hospital, Weifang 261000, Shandong, People’s Republic of China *For correspondence. E-mail: [email protected]. Received 12 June 2018; revised 18 April 2019; accepted 19 May 2019 Abstract. Although it is known that the parental carriers of chromosomal translocation are considered to be at high risk for spontaneous abortion and embryonic death, normal gestation and delivery remain possible. This study aims to investigate the genetic factors of a Chinese infant with multiple malformations and severe postnatal development retardation. In this study, the routine cytogenetic analysis, chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) analysis were performed. Conventional karyotype analyses revealed normal karyotypes of all family members. CMA of the DNA of the proband revealed a 8.3 Mb duplication of 5q35.1-qter and a 6.9 Mb deletion of 11q24.3-qter. FISH analyses verified a paternal tiny translocation between the long arm of chromosomes 5 and 11. Our investigation serves to provide important information on genetic counselling for the patient and future pregnancies in this family. Moreover, the combined use of CMA and FISH is effective for clarifying pathogenically submicroscopic copy number variants. Keywords. 5q/11q translocation; karyotyping; chromosomal microarray analysis; fluorescence in situ hybridization; growth retardation. Introduction pattern is distinctive (Di Gregorio et al. 2014). Moreover, for microscopically invisible chromosome rearrangements, Reciprocal chromosomal translocations (RCTs) are par- derivative chromosomes are probably more common than ticularly frequent among couples experiencing recurrent expected, since they may appear normal at standard reso- miscarriages, embryonic death and infertility (Martin lution karyotype (de Vries et al. 2001). 2008). RCTs are produced by breakage and exchange of In this study, we report the clinical findings detected in a distal segments between specifically nonhomologous chro- Chinese infant who is a carrier of unbalanced, paternally mosomes and the incidence is about one in 712 newborns inherited 46, XY, der (11) t (5;11) (q35.1; q24.3). This is (Nielsen and Wohlert 1991). Unbalanced spermatozoa are the first of such a kind of karyotype and our study serves detected in male carriers of balanced RCTs with a fre- to define the genetic aetiology of the patient. quency of 18.6–80.7% (Benet et al. 2005). Fertilization with an aneuploid sperm generates monosomy or trisomy in the foetus and is the major causes of spontaneous abortions Material and methods or neonate malformations (Causio et al. 2002). It is well established that the carriers of balanced RCT Subjects usually have normal phenotypes and are considered to be at high risk for spontaneous abortion and chromosomally The propositus is a nine-month old infant and was born at abnormal offspring (Niknejadi et al. 2014). Although rou- 40 weeks of gestation (WG) by spontaneous delivery with tine cytogenetic analysis is an effective method to detect a birth weight of 2750 g (<10th centile) and a length of microscopically visible chromosome rearrangements, the 46 cm (<10th centile). He was referred to us because of limit of routine analysis is estimated to be 5–10 Mb at the the poor response and severe growth restriction. Clinical 500–550 bands level, at least in regions where the band examination revealed signs of microcephaly, micrognathia, 0123456789().: V,-vol 77 Page 2 of 8 Xiangyu Zhao et al. Figure 1. Conventional cytogenetic analysis. (a) Pedigree of the family. (b) The G-banding result for the proband. (c) The G-banding result for the proband’s mother. (d) The G-banding result for the proband’s father. bulbous nasal tip and hypotonia. Cardiac colour ultra- Chromosomal microarray analysis sound indicated congenital heart disease, membranous septal defect, mild ascending aortic constriction, severe Chromosomal microarray analysis was performed by pulmonary hypertension, patent foramen ovale and left Affymetrix Cytoscan 750K Array (Affymetrix, Santa ventricular false tendons. The proband’s mother had a Clara, USA). Genomic DNAs were extracted by using a history miscarriages of thrice. This study was performed DNA Extraction kit (Qiagen). The labelling and hybridiza- at Linyi People’s Hospital, Shandong, China. The insti- tion procedures were performed following manufacturer’s tutional ethical review committees (Ethics Committee of instructions. The raw data of chromosomal microarray was Linyi People’s Hospital) approved the research protocol, analysed by Affymetrix Chromosome Analysis Suite Soft- and the proband’s relatives provided written informed con- ware (ChAS; v2.1). All genomic co-ordinates were taken sent. from the February 2009 (hg19) human reference sequence (NCBI Build 37). Genes and online Mendelian inheritance in man (OMIM) references were taken from RefSeq and Conventional cytogenetic analysis OMIM entries, respectively. The peripheral blood lymphocytes of proband and his parents were cultured using standard protocol and the G- Fluorescence in situ hybridization (FISH) analysis banding was performed using standard technique as in Li et al. (2013). Slides were scanned using Olympus BX53 FISH was performed to identify the speculated tiny microscope (Olympus, Japan). Chromosomal aberrations translocation using locus-specific probes for chromosomes were classified using International System for Human 5 and 11 according to the manufacturer’s instructions. The Cytogenetic Nomenclature (Stevens-Kroef et al. 2017). hybridized chromosomal spreads were analysed using a Identification of a 5q/11q translocation Page 3 of 8 77 Figure 2. Chromosomal microarray analysis. (a) The result shows a 8.3 Mb duplication of 5q35.1→q35.5 denoted by a blue bar. (b) The result shows a 6.9 Mb deletion of 11q24.3→q25 denoted by a red bar. 77 Page 4 of 8 Xiangyu Zhao et al. Figure 3. FISH analysis. (a) The patient’s results showed triploid red signals of CNOT6 (5q35.3) and haploid red signal of JAM3 (11q25). Green marks indicate the centromere of chromosomes 5 and 11. (b) The results of the patient’s mother showed normal chromosomes 5 and 11. (c) The results of the patient’s father showed signals of the derivative chromosomes 5 and 11. Identification of a 5q/11q translocation Page 5 of 8 77 Figure 4. Translocation of the patient’s father. (a) Ideogram of derivative 5 chromosome. (b) Ideogram of derivative 11 chromosome. fluorescent microscope equipped with appropriate filters. FISH analysis Slides were scored by the number of probe signals at each metaphase. For each target area, 20 hybridized metaphase Following the microarray analysis, metaphase FISH anal- cells were analysed. ysis was performed on the family members. The proband’s results showed triploid signals of 5q35.3 and haploid Results signal of 11q25 (figure 3a). The results of proband’s mother showed normal signals and integrated chromo- Conventional cytogenetic analysis somes 5 and 11 (figure 3b). However, the FISH results of proband’s father indicated a translocation between 5q35.1 The family pedigree is shown in figure 1a. Using peripheral and 11q24.3 (figure 3c). Derivative 5; 11 chromosome and white blood cells of all the family members, G-banding chromosome ideograms of 5; 11 translocation are shown in analysis was conducted. The results showed that the figure 4. These results indicate that a speculated transloca- proband and his parents had likely normal karyotypes (fig- tion is verified to be positive by FISH analysis with specific ure 1,b–d). probes and our patient’s derivative chromosome 11 was inherited from his paternal side. Chromosomal microarray analysis To understand the possible cause for the proband’s multi- ple malformations and growth retardation, chromosomal Discussion microarray analyses analysis was conducted using periph- eral white blood cells of all the family members. As Tiny RCTs, also can be defined as microscopically invisible shown in figure 2a, chromosome 5 has a copy num- chromosome rearrangements, are relatively rare events and ber gain corresponding to a 8.3 Mb segment located at can be a potential disaster for individual de novo patient 5q35.1→q35.3 (ranging from positions 172,347,562 to (Hoo et al. 1982). In the present study, our patient carried 180,678,091). Chromosome 11 has a copy number loss cor- a 8.3 Mb duplication of 5q35.1-qter and a 6.9 Mb deletion responding to a 6.9 Mb segment located at 11q24.3→q25 of 11q24.3-qter. (ranging from positions 128,021,090 to 134,938,470) (fig- From a cytogenetic point of view, a partial duplica- ure 2b), i.e. terminal duplication at positions 5q35.1q35.3 tion of the 5q terminus is known to be associated with and 11q24.3q25. In addition, the CMA results of the Hunter–McAlpine syndrome (Hunter et al. 2005). When proband’s parents were normal. compared with the previously published reviews on pure 77 6of8 Page Table 1. Clinical features of our patient and previous cases with 5q terminus duplication. Fryns et al. (1987) Witters et al. (1998) Coelho et al. (1996) Chen et al. (2006) Jamsheer et al. (2013) Current study Gain region