Is a gene for microcephaly located on chromosome 1?

A 3-month-old boy with true microcephaly showed the same balanced reciprocal translocation 1q4p as his carrier mother. This reciprocal translocation had been transmitted for at least four generations. Different banding techniques allowed one to describe the rearrangement as: rcp t(1;4) (1pter----1q31::4p161----4pter; 4qter----4p153::1q321----1qter). On the other hand, the proband's father seemed to be a border-line mentally retarded and one of his relatives suffered from mental retardation of unknown origin. Taking into account all these results together with the current literature, it was concluded that the microcephaly appearing in our case could be due to the following two facts: (a) the father was an heterozygote for the gene for microcephaly, and (b) damage or a minute deletion on chromosome 1 between 1q31 and 1q321 bands could occur in the mother's family resulting in a mutation for microcephaly. If this was so, the gene for microcephaly should be located on chromosome 1 at the level of the 1q31-1q321 junction.