We report on a boy who had multiple synostosis syndrome 1, an autosomal dominant disorder characterized by progressive symphalangism, multiple joint fusions, conductive deafness, and mild facial dysmorphism. In addition the boy developed delay of puberty, bone age, and closure of the epiphyseal lines of long bones with tall stature. These findings and decreased plasma LH and FSH levels at age 19 years were compatible with hypogonadotropic hypogonadism. G-banded chromosomes showed a balanced translocation t(10;17)(p15.3;q22). Chromosomal FISH analysis, using a series of BAC clones surrounding the translocation breakpoints, detected a 2.2-3.9 Mb deletion at 17q22. The deletion encompassed NOG, a gene responsible for multiple synostosis syndrome 1. It was assumed that a gene for pituitary secretion of gonoadotropic hormones was deleted at the 17q22 segment.