Abstract

Prometaphase chromosomes from a 16 year old boy with hypogonadotrophic hypogonadism and anosmia (Kallmann syndrome) showed a tiny chromosome fragment attached to the long arm of one chromosome 1 without a visible reciprocal translocation chromosome. Chromosome painting with libraries from chromosomes 1 and X excluded a t(X;1) translocation, but failed to detect a second translocation chromosome. Through reverse chromosome painting, an unbalanced der(1), t(1;10) (q44;q26) translocation could be detected. This is the third case of Kallmann syndrome with a de novo rearrangement between two autosomes. The distal long arm of chromosome 1 may contain a candidate locus for a gene, mutations of which may cause the Kallmann phenotype; a 10q location seems less likely.