In 1990, Lambotte syndrome was reported as an apparently autosomal recessive multiple congenital anomaly/mental retardation (MCA/MR) syndrome observed in 4 of 12 sibs from a probably consanguineous mating [Verloes et al., Am J Med Genet 1990; 37:119-123]. Major manifestations included intrauterine growth retardation (IUGR), microcephaly, large soft pinnae, hypertelorism, beaked nose, and extremely severe neurologic impairment, with holoprosencephaly in one instance. After the observation of a further affected child born of one unaffected sister, in situ hybridization analysis and chromosome painting techniques demonstrated a subtle t(2;4)(q37.1; p16.2) translocation in the mother, suggesting a combination of 2q/4p trisomy/monosomy in all of the affected children of the family. Many private sporadic or recurrent MCA/MR syndromes maybe due to similar symmetric translocations, undetectable by conventional banding techniques.