Phenotypic analysis and growth response to different growth hormone treatment schedules in two siblings with an inactivating mutation in the growth hormone-releasing hormone receptor gene

Height gain with combined growth hormone and gonadotropin-releasing hormone analog therapy in two pubertal siblings with a growth hormone-releasing hormone receptor mutation

CONTEXT

Patients with GHRH receptor (GHRH-R) mutations present with familial isolated GH deficiency, which untreated leads to a severely compromised adult height. Few data are available about the efficacy of treatment with GH in combination with a GnRH analog (GnRHa) in adolescence.

OBJECTIVE

The objective of the study was to describe the evolution of growth and skeletal age of a brother and sister of Moroccan descent with a homozygous GHRH-R mutation who presented at an advanced age (16 and 14.9 yr, respectively) and pubertal stage (Tanner stage G4 and B3, respectively) with a height of -5.1 sd score and -7.3 sd score on treatment with a combination of GH and GnRHa for 2.5 and 3 yr followed by GH alone.

METHODS

GH was given in a dosage of 0.7 mg/m2.d (25 microg/kg.d) sc and triptorelin in a dosage of 3.75 mg per 4 wk im. Height and pubertal stage were measured three-monthly, bone age yearly.

RESULTS

Combined GH and GnRHa treatment resulted in a height gain of 24 and 28.2 cm, respectively, compared with the initial predicted adult height by the method of Bayley and Pinneau. Adult height was within the population range and well within the target range.

CONCLUSIONS

Our patients demonstrate that, in case of isolated GH deficiency caused by a GHRH-R mutation, combined treatment of GH and GnRHa can be very effective in increasing final height, even at an advanced bone age and pubertal stage.