Introduction
Reciprocal chromosomal translocation (RCT) is one of the most common
human chromosomal abnormalities. Balanced RCT does not contain the
variation in the number of chromosomes, but only the rearrangement of
genetic material[1]. As we know, balanced RCT carriers will have
greater risk to experience recurrent miscarriages, embryonic death,
infertility or giving birth to defective offspring[2].
Copy number variants (CNVs) are also important causes of birth defects,
resulting in various clinical manifestations, including growth and
developmental abnormality, mental retardation, visceral malformation and
special facial features, etc[3]. At present, various syndromes are
verified to be caused by CNVs, such as 22q11.2 deletion syndrome,
Cri-du-chat syndrome, Williams syndrome and so on[4].
Above all, birth defects are important challenges affecting the quality
of the birth population. Genetic counseling as well as prenatal
diagnosis is effective method to decrease the rate of birth
defects[5].
In this study, we report the clinical findings detected in a Chinese
pedigree [Figure 1]. The proband was diagnosed by CMA to carry a
25.6 Mb duplication of 8q24.12-q24.3 and a 16.5 Mb deletion of
18q21.33-q23. Karyotype analysis showed that the karyotype of the
proband is paternally inherited 46,XX,der(18)t(8;18)(q24.1;q21.3). This
is the first of such a kind of karyotype to be reported. At the same
time, the mother of the proband was pregnant for 18 weeks. CMA and
karyotype analysis of amniotic fluid cells indicated that the fetus also
carried the same karyotype as that of the proband. The couple decided to
terminate the pregnancy after genetic counseling. Functional enrichment
analysis of the genes involved was also carried out to find out the key
genes causing the phenotype of the proband.