The occurrence of system balanced complex chromosome rearrangements is extremely rare among humans. The majority of such cases occurs as de novo and have been described in children with congenital abnormalities and mental retardation [1,2,3].

So far only a small number of cases with segregation of complex chromosomal rearrangements in a balanced form through two or more generations have been reported. The majority of familial balanced complex chromosome rearrangements that involve three or more chromosomes have been reported in women, ascertained through the birth of a malformed child or through repeated spontaneous abortions [3,4,5,6]. This observation may be a result of biased ascertainment, as male carriers may be less likely to produce unbalanced progeny or may be infertile [6,7,8,9,10].

We report a rare case with a 4-way reciprocal translocation t(1; 4; 20; 9) ascertained during prenatal diagnosis.