A familial balanced t(7;9) (q36;q34) was reported recently. Analysis of the craniofacial features of 3 of the sibs showed signs of holoprosencephaly. Two of the sibs have an unbalanced derivative chromosome leading to del(7) (q36) and dup(9) (q34), while the other has a cytogenetically balanced translocation. These findings, together with several reports associating holoprosencephaly with terminal 7q deletions, indicate that a putative locus for holoprosencephaly resides at or near 7q36. It should now be feasible to clone this locus.