Balkan Journal of Medical Genetics

DOUBLE TRANSLOCATION: AN INTERESTING FAMILY HISTORY
Uysal A1,*, Uludağ A2, Sılan F2, Erçelen N3, Zafer C4, Özdemir Ö2
*Corresponding Author: Assistant Professor Ahmet Uysal, Department of Obstetrics and Gynecology, Çanakkale Onsekiz Mart University, Çanakkale, Turkey; Tel.: +90-533-263-55-40; Fax: +90-0286-263-59-56; E-mail: drahmetuysal@hotmail.com
page: 77

INTRODUCTION

Parental chromosomal irregularity was first proposed as a cause of recurrent spontaneous abortion in 1967. In the years following various studies on couples with a history of two or more spontaneous miscarriages found rates of chromosomal irregularity as low as 2.0% and as high as 17.75%. In spite of different rates of chromosomal irregularity found in these studies, reciprocal or Robertson-type balanced translocations (average 4.03%) were highest followed by other irregularities such as inversion and gonosomal chromosome mosaicism [1,2]. For patients recognized as carriers of reciprocal or Robertson-type translocations, chromosome analysis of parents and known first-degree relatives can determine whether the translocation is de novo or familial. While chromosomal translocations are seen in 0.2% of newborns, this rises to 2.5% in couples with repeated unsuccessful conceptions and is 9.2% in couples with repeated miscarriages [2-4]. Robertsonian translocations occur when the p arm (satellite) of a series coding repetitive ribosomal RNA of two acrocentric chromosomes (13, 14, 15, 21, 22) is lost and combines with the q arm centromere. While balanced reciprocal translocation does not have loss between two non homologous chromosomes, it mainly occurs due to displacement of the end regions of the chromosomes [3,4]. Before preimplantation genetic diagnosis (PGD) can be carried out for translocation carriers, a preparation stage must be completed. This stage in a couple recognized as translocation carriers by cytogenetic analysis verifies fracture points by fluorescent in situ hybridization (FISH) analysis and is very important in determining which probes will be used in PGD studies. This requires blood samples from both partners for chromosome examination and recording fracture points on the chromosomes using the FISH method. Again, if the candidate father was a translocation carrier, it may have been possible to determine the normal or balanced/unbalanced gamete ratio using FISH analysis of sperm cells before the PGD procedure was implemented. The FISH analysis of sperm cells, especially in reciprocal translocation carriers, is very useful to estimate the balanced/unbalanced embryo ratio and as a treatment indicator [5]. This study investigated a couple who applied to our clinic due to infertility and a history of family chromosomal anomalies. The male partner was a balanced double translocation carrier and the history of other members of the family was researched. Case Report. A couple married for 4 years was referred to the genetic clinic due to infertility and family chromosome anomalies. A GTG-band chromosome analysis indicated 46,XX normal and 45,XY, t(3;18)(q11;ptel)t(13;14)(q10; q10) karyotypes. The male partner (IV-5) (Figure 1) was phenotypically normal with normal intelligence and healthy other than infertility. His sister (IV-8) who experienced repeated miscarriages was found carried he same double translocation. The FISH analysis was done again and confirmed the karyo-type. For FISH, WC 13 blue, WC 14 red, (Poseidon DNA Probes, Kreatech Biotechnology, Amsterdam, The Netherlands); WCP 3, spectrum orange, WCP 18, spectrum green, WCP (Whole Chromosome Paint) (Vysis Inc., Downers Grove, IL, USA) were used. Other members of the family were called for chromosome analysis and the proband’s mother (III-6), who had two miscarriages and three healthy children, carried the same double translocation. The proband’s single sister (IV-10) (Figure 2) carried only reciprocal translocation, while the proband’s grandfather (II-4) (Figure 3) only carried a Robertsonian translocation. The mother (III-6) had a brother and sister who both died from congenital anomalies at age 6 months and a brother who died from cancer of the pharynx at age 37. The mother’s only living sibling had normal chromosome analysis results (Figure 4). Analysis of the proband’s sperm found a normal 50 million/mL sperm count, however, morphologic evaluation using the Kruger method found 99.0% teratospermia with head anomalies. Using the intra cytoplasmic sperm injection (ICSI) method on the proband’s wife, two late divided embryos were obtained from seven eggs and transferred on the third day; however, β-human chorionic gonadotropin (β-HCG) had not increased on the 12th day after transfer. Genetic counseling was provided to the proband’s wife and sister; in light of PGD, in vitro fertilization (IVF) was presented as an option.

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