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Cytogenetic and Genomic Analysis of a Patient with Turner Syndrome and T(2;12): a Case Report Paola E

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Cytogenetic and Genomic Analysis of a Patient with Turner Syndrome and T(2;12): a Case Report Paola E Leone et al. Mol Cytogenet (2020) 13:46 https://doi.org/10.1186/s13039-020-00515-0 CASE REPORT Open Access Cytogenetic and genomic analysis of a patient with turner syndrome and t(2;12): a case report Paola E. Leone1*† , Verónica Yumiceba1†, Ariana Jijón‑Vergara1, Andy Pérez‑Villa1, Isaac Armendáriz‑Castillo1, Jennyfer M. García‑Cárdenas1, Santiago Guerrero1, Patricia Guevara‑Ramírez1, Andrés López‑Cortés1, Ana K. Zambrano1, Jesús M. Hernández‑Rivas2,3, Juan Luis García3,4 and César Paz‑y‑Miño1*† Abstract Background: Turner syndrome is a genetic disorder that afects women. It is caused by an absent or incomplete X chromosome, which can be presented in mosaicism or not. There are 12 cases of Turner syndrome patients who present structural alterations in autosomal chromosomes. Case presentation: The present case report describes a patient with a reciprocal, maternally inherited translocation between chromosomes 2 and 12 with a mosaicism of X monosomy 45,X,t(2;12)(p13;q24)[95]/46,XX,t(2;12)(p13;q24) [5]. Through genetic mapping arrays, altered genes in the patient were determined within the 23 chromosome pairs. These genes were associated with the patient’s clinical features using a bioinformatics tool. Conclusion: To our knowledge, this is the frst case in which a translocation (2;12) is reported in a patient with Turner syndrome and confrmed by conventional cytogenetics, FISH and molecular genetics. Clinical features of our patient are closely related with the loss of one X chromosome, however mild intellectual disability can be likely explained by autosomal genes. The presence of familial translocations was a common fnding, thus emphasizing the need for familiar testing for further genetic counselling. Keywords: Turner syndrome, Reciprocal translocation, Cytogenetics, Genetic mapping arrays, FISH whole chromosome is compatible with life [1]. Tis con- dition presents several cytogenetic variants, being the Background monosomy 45,X the most frequent (45–55%), followed Turner syndrome (TS) is a chromosomal disorder caused by structural changes in a X chromosome (25–30%) as by a complete or partial monosomy of the X chromo- isochromosome of the long arm, isochromosome mosaic, some. It afects about 1 out of every 2500 newborn girls. deletions and ring chromosomes [1, 2]. In Ecuador, X Tis is the only genetic disorders where the absence of a chromosome monosomy represents 40.42%, TS mosaic accounts for 25.3% and structural alterations of X chro- mosome appeared in 7.9% of TS patients [3]. *Correspondence: [email protected]; [email protected] TS complex phenotype is characterized by growth fail- † Paola E. Leone, Verónica Yumiceba and César Paz‑y‑Miño contributed ure, delayed puberty, primary amenorrhea, gonadal dys- equally to the study 1 Centro de Investigación Genética y Genómica, Facultad de Ciencias de genesis, ovarian insufciency, alopecia, hirsutism, low la Salud Eugenio Espejo, Universidad UTE, Av. Mariscal Sucre y Av. Mariana extremity lymphedema, nail dysplasia or hypoplasia, de Jesús, Sede Occidental, Bloque I, 2 Floor, 170129 Quito, Ecuador vitiligo, short and webbed neck (pterygium colli), low Full list of author information is available at the end of the article © The Author(s) 2020. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creat iveco mmons .org/licen ses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creat iveco mmons .org/publi cdoma in/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Leone et al. Mol Cytogenet (2020) 13:46 Page 2 of 9 posterior hairline at the back of the neck, wide-spaced has mild tricuspid regurgitation and pulmonary arterial nipples, inverted nipples, shield shaped thorax, low set hypertension (41 mmHg). ears and long term complications such as kidney, car- Physical examination in the frst medical appointment diovascular, and ophthalmological problems [4]. Around on June 2006 evidenced low set ears, pectus excavatum, two-thirds of the girls with TS have the maternal X chro- ogival palate and wide-spaced nipples (Fig. 2). Based mosome, ruling out the possibility meiotic error in elder on the symptoms and karyotype, TS was diagnosed. mothers [5]. From 7 years of age, she has been diagnosed with myo- For TS diagnosis, a physical assessment and cytoge- pia. Te second medical appointment in 2012 confrmed netic testing is needed. Women with 45,X are diagnosed the diagnosis and determined a reciprocal translocation when they are born, mainly due to their dysmorphic using Giemsa trypsin G-banding (GTG). In 2015, she characteristics and cardiovascular complications. How- had thyroid disorders and was treated with levothyrox- ever, in other cases the diagnosis is postponed even until ine, besides her tonsils were removed. Te patient did adolescence, when the girls displayed absent of pubertal not have cardiovascular diseases. She had mild intel- development, amenorrhea, and infertility [6]. lectual disability. At puberty (15 years old), she showed Within structural chromosomal abnormalities, translo- primary amenorrhea, underdeveloped breasts, juvenile cations are defned as the exchange of chromosomal seg- arthritis, nail dysplasia, short stature (1 m, − 9.76 SDS), ments of between two non-homologous chromosomes. and lymphedema of the feet, so she wore orthopedic Tere are two types of translocations: reciprocal and insoles for walking. In the third medical examination Robertsonian [7]. Te resulting chromosomal rearrange- the 16-year-old patient has an estimated 3-year delay in ments can be a balanced or unbalanced. Double strands bone-age. Te patient was on a hormone replacement breaks are prerequisites for translocations and the phe- therapy (patches) to stimulate sexual development. As notype of unbalanced translocation carriers depends on an ultrasound scan showed no ovaries, genetic coun- the size, and location of the break [8]. seling was recommended to overcome future infertility Te coexistence of autosomal translocations and struc- complications. tural/numerical abnormalities of the X chromosome are a rarely reported, there are 12 cases published [9–20]. Cytogenetic and genomics assessment of proband Here we describe a mosaic Turner syndrome patient and parents with a maternally inherited reciprocal translocation with In 2006, the patient was diagnosed with a monosomy X breakpoints at 2p13 and 12q24. mosaicism 45,X[90]/46,XX[10]. In 2012, with a better G-banding resolution, a reciprocal translocation with Case presentation a 45,X,t(2;12)(p13;q24)[95]/46,XX,t(2;12)(p13;q24)[5] Clinical report karyotype was found (Fig. 3a). To determine whether the Te patient was born on July 2000 at 32 weeks of gesta- translocation was inherited or de novo, her parents were tion after oligohydramnios diagnosis. Her measurements at birth were as follows: weight 2.4 kg (1.65 SDS), length 46.5 cm (1.53 SDS) and head circumference 31.5 cm (1.75 SDS). During the frst year of life, she received endocrine therapy to enhance growth and ameliorate join pain. She was the second ofspring of healthy, non-consanguineous parents, who had a previous miscarriage (Fig. 1). When she was 5 years old, an echocardiography showed she Fig. 1 Family tree of the Turner syndrome proband carrier of the Fig. 2 Clinical photographs of the patient. a At 10 years old, b at translocation (2;12) 16 years old Leone et al. Mol Cytogenet (2020) 13:46 Page 3 of 9 Fig. 3 Patient and parents’ karyotypes. a Patient with mosaic X chromosome monosomy and t(2;12). b Father with normal karyotype. c Mother carrier of the t(2;12) karyotyped. Te father had a normal karyotype, 46,XY scanned with GeneChip™ 3000 (Afymetrix, Santa Clara, (Fig. 3b), while the mother carried the reciprocal trans- CA, USA). Te software used for the analysis was Afym- location 46,XX,t(2;12)(p13;q24) and transmitted it to her etrix Chromosome Analysis Suite version 2.1. Te quality child (Fig. 3c). control thresholds were: SNPQC ≥ 15.0; MAPD ≤ 0.25; Te reciprocal chromosomal exchange between chro- Waviness SD ≤ 0.12. Smoothing setting was On and mosome 2 and 12 was visualized using fuorescence the Joining Option marked 25 markers, 200 kbp. Te probes on the patient’s lymphocytes. Signals for the 2pter microarray data were interpreted according to the anno- (Agilent, Santa Clara), 2p23 (ALK), and 2p21 (EML4) tations of genome version “Genome browser hg19, Feb- (Abbott Molecular, Abbott Park, IL) probes were in one ruary 2009” (GRCh37/hg19). Array results of the proband normal chromosome 2 and in the derivative chromo- showed Copy Number Variations (CNV) in several auto- some 12, der(12). One signal of the 12qter (Agilent, Santa somes and sex chromosomes, being the loss of the X Clara) was located in the telomere of chromosome 12 chromosome the largest genomic alteration as indicated: and in the derivative chromosome 2, der(2) (Fig. 4). arr[GRCh37] Xp22.33p11.22(168,551_53,465,323) × 1 Extracted DNA from the patient and her mother were dn,Xp11.22(53,465,326_53,477,877) 4 mat,Xp11.
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