ESPE2024 Free Communications GH and IGFs (6 abstracts)
1Dutch Growth Research Foundation, Rotterdam, Netherlands. 2Albert Schweitzer Hospital, Dordrecht, Netherlands. 3Leiden University Medical Center, Leiden, Netherlands. 4University Medical Center Utrecht - Wilhelmina Children's Hospital, Utrecht, Netherlands. 5Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands. 6University Medical Center Groningen, Groningen, Netherlands. 7Radboud University Medical Center, Nijmegen, Netherlands. 8Erasmus University Medical Center - Sophia Children’s Hospital, Rotterdam, Netherlands. 9Leiden University Medical Center - Willem-Alexander Children’s Hospital, Leiden, Netherlands
Background: The NPR2 gene plays a critical role in the human growth plate. Pathogenic NPR2 variants can result in varying degrees of short stature. The majority of subjects have no specific clinical findings and are likely classified as idiopathic short stature.
Objective: To describe the phenotypic spectrum, analyze genotype-phenotype correlations and assess the response and safety of growth hormone (GH) treatment in children with a heterozygous pathogenic NPR2 variant.
Patients: Twenty-seven (18 boys, 9 girls) short-statured children with pathogenic NPR2 variants and treated for ≥1 year with GH (1.4 mg/m2/day) were identified in the Dutch National Registry of GH treatment in children.
Results: In our cohort of 27 children, we identified 18 different pathogenic NPR2 variants. Most variants (10/18) were located in the ligand binding domain. Seven subjects had a truncating variant, 18 subjects a non-truncating variant and 2 subjects a splice site variant. Median (IQR) baseline height SDS was -2.9 (-3.3 to -2.4). Fifteen subjects were prepubertal, 12 subjects pubertal. In ~30% of children no specific clinical or dysmorphic features were reported, however, the majority of patients did show minor features suggestive of a skeletal dysplasia. Dysmorphic features of the hands were most frequently described (14/27) including brachydactyly and cone-shaped epiphysis. Sitting height to height ratio was ≥1.0 SDS in 13 subjects. Subjects with a truncating NPR2 variant had a shorter height SDS compared to subjects with a non-truncating variant (-3.3 and -2.5 respectively, P = 0.019). After 2 years of GH treatment, gain in height SDS in prepubertal children was 1.2 (0.9 to 1.4, P = 0.003). In pubertal children height SDS remained stable, which is in contrast to the loss in height SDS that is reported in untreated, pubertal NPR2 subjects. Six children reached adult height (AH): 3 subjects reached an AH ≥-2 SDS, in 2 subjects AH SDS had improved in comparison to the untreated affected parent and in 1 subject AH was comparable with the untreated affected parent. GH treatment was well-tolerated without the report of severe adverse events.
Conclusion: The majority of patients with a heterozygous pathogenic NPR2 variant have some features suggestive of skeletal dysplasia. Careful examination, especially of the hand, is helpful in identifying which children to test for a NPR2 variant. We furthermore show that the majority of NPR2 patients have a significant response to GH during 2 years of treatment.