Introduction: Various types of mutations in GHRHR cause isolated growth hormone deficiency type 1B. Here, we report the clinical features associated with deletion of whole GHRHR gene for the first time.
Case: A four-yearand-nine-month-old otherwise healthy girl was admitted due to short stature. She was born at term with a birthweight of 3750 gr. Her height velocity slowed down after 2 years of age. The mother (157.8 cm, −0.82 SDS) and father (162 cm, −1.99 SDS) were second-degree cousins. Her weight was 11.8 kg (−3.54 SDS) and height 91 cm (−3.38 SDS). Infantile facial appearance and prominent forehead were noted. Biochemistry, blood count, and thyroid function tests were normal and bone age was compatible with 2.5 years. IGF-1 and IGFBP-3 levels were low. The peak GH levels following L-Dopa and ITT were 0.280 ng/mL and 0.420 ng/mL, respectively. Magnetic resonance imaging revealed pituitary hypoplasia. Somatropin treatment was commenced. At the most recent follow-up when she was 12-years and 7-month-old, her height was 152.2 cm (−0.45 SDS), BMI 17.5 (−0.37 SDS), and pubertal development compatible with Tanner stage 3. GH1 sequencing was normal but homozygous whole-gene deletion of GHRHR was found. Both parents were heterozygous for this mutation. IGF-1 levels were low in the father and low-normal in the mother. Glucagon stimulation tests revealed normal peak growth hormone responses in the mother (4.85 ng/mL) and father (10.4 ng/mL).
Conclusion: The clinical features of homozygous whole-gene deletion of GHRHR are comparable with those of other types of GHRHR mutations. The carrier parents demonstrated normal growth hormone responses to the stimulation tests despite low IGF-1 levels.
27 Sep 2018 - 29 Sep 2018