Growth hormone neurosecretory dysfunction associated with ring chromosome 18.

The patient was a girl 5 years and 1 month old of markedly short stature (-3.9 SD) for her chronological age. Although her karyotype was 46, XX, r(18)(p11q23), there were no symptoms of a chromosomal deletion. Other authors have described cases with a ring autosome showing a phenotype with short stature alone as 'ring syndrome', regardless of which autosome is involved. The present case seems to fall into this category. Although blood growth hormone (GH) showed normal responses to four types of provocative tests, the mean value of blood GH levels obtained at 30 min intervals for 24 h was low, indicating the existence of growth hormone neurosecretory dysfunction (GHND).