Prenatal diagnosis of the maternal derivative chromosome der(15)t(Y;15)(q12;p13) in a dizygotic twin pregnancy

Pei-Yi Chen^a, Jui-Hung Yen^b, Ching-Feng Cheng^{c, d}, Pao Chu Chen^e, Yi-Shian Li^a, Tzu-Ying Li^a, Chung-Nan Yeh^a, Jye-Siung Fang^{a, b},

^a Center of Medical Genetics, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
^b Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien, Taiwan
^c Department of Pediatrics, Buddhist Tzu Chi General Hospital and Tzu Chi University, Hualien, Taiwan
^d Institute of Biomedical Science, Academia Sinica, Taipei, Taiwan
^e Department of Obstetrics and Gynecology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan

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Open Access funded by Buddhist Compassion Relief Tzu Chi Foundation

Abstract

Sex chromosome translocations are unique and must be considered separately from translocations between autosomes. Here, we describe the first prenatal case of one twin fetus with an unbalanced translocation between chromosome Y and chromosome 15, presenting a 46,XY,der(15)t(Y;15) karyotype. The other twin had a normal 46,XY karyotype. Cytogenetic analysis of the parental chromosomes revealed that the father had a normal 46,XY karyotype, whereas the mother exhibited a 46,XX,der(15)t(Y;15) karyotype. Thus, the proband inherited this translocation from the mother. Fluorescence in situ hybridization analyses demonstrated that the breakpoint on chromosome Y involved a heterochromatin region (Yq12), while that on chromosome 15 involved a p-arm region (15p13). At 37 gestational weeks, healthy twins were delivered vaginally. We conclude that accurate identification of der(15) chromosomal content can facilitate not only prenatal diagnosis of a chromosomal aberration in one twin, but also prediction of the fetal phenotype.

Keywords

Prenatal diagnosis; Sex chromosome aberrations; Twin pregnancy