DNA testing in patients with GH deficiency at the time of transition

Whole Exome Sequencing Uncovered the Genetic Architecture of Growth Hormone Deficiency Patients

PURPOSE

Congenital growth hormone deficiency (GHD) is a rare and etiologically heterogeneous disease. We aim to screen disease-causing mutations of GHD in a relatively sizable cohort and discover underlying mechanisms via a candidate gene-based mutational burden analysis.

METHODS

We retrospectively analyzed 109 short stature patients associated with hormone deficiency. All patients were classified into two groups: Group I (n=45) with definitive GHD and Group II (n=64) with possible GHD. We analyzed correlation consistency between clinical criteria and molecular findings by whole exome sequencing (WES) in two groups. The patients without a molecular diagnosis (n=90) were compared with 942 in-house controls for the mutational burden of rare mutations in 259 genes biologically related with the GH axis.

RESULTS

In 19 patients with molecular diagnosis, we found 5 possible GHD patients received known molecular diagnosis associated with GHD (NF1 [c.2329T>A, c.7131C>G], GHRHR [c.731G>A], STAT5B [c.1102delC], HRAS [c.187_207dup]). By mutational burden analysis of predicted deleterious variants in 90 patients without molecular diagnosis, we found that POLR3A (p = 0.005), SUFU (p = 0.006), LHX3 (p = 0.021) and CREB3L4 (p = 0.040) represented top genes enriched in GHD patients.

CONCLUSION

Our study revealed the discrepancies between the laboratory testing and molecular diagnosis of GHD. These differences should be considered when for an accurate diagnosis of GHD. We also identified four candidate genes that might be associated with GHD.

Effects of genetic variability of the caprine homeobox transcription factor HESX1 gene on performance traits

HESX1 plays a key role in the development of the forebrain and pituitary gland and produces potential effects on performance traits. The objective of this study was to detect and assess the associations of the possible polymorphisms of six loci within HESX1 gene with performance traits in Chinese 1,119 goats. Only one novel SNP (NM_001494116:g.307049A > G) locating on IVS1 + 348A > G was identified and detected by HaeIII forced-RFLP-PCR. The frequencies of allele "G" varied from 0.025 to 0.245 in analyzed populations with the Hardy-Weinberg equilibrium (P > 0.05). Genotypic and allelic frequencies were found to be significantly different in four breeds (chi(2) = 147.674, df = 6, P < 0.001; chi(2) = 157.250, df = 3, P < 0.001, respectively), implying that the distribution of genotypic and allelic frequencies of goat HESX1 gene was significantly associated with different goat utilities (cashmere, meat and dairy). Association analysis results revealed no significant effects of caprine HESX1 gene on body sizes in XNSN population (P > 0.05) and cashmere traits in IMWC population (P > 0.05). Significant statistical of HESX1 gene with body weight was found (*P < 0.05). The genotype AA showed significantly higher body weight than those of AG in 2-year-old age (*P < 0.05), while the AA genotype was senior to AG genotype in 4-year-old body weight trait (*P < 0.05). These suggestions indicated that the HESX1 gene has significant effect on goat body weight depending on ages, which is accordance with the function repressor of the HESX1.

Reassessment of the optimal growth hormone cut-off level in insulin tolerance testing for growth hormone secretion in patients with childhood-onset growth hormone deficiency during transition to adulthood

CONTEXT

Retesting of patients with childhood-onset growth hormone deficiency (CO-GHD) is recommended after completion of growth hormone (GH) treatment.

AIM

To identify patients who are at risk of persistent GHD, and to evaluate the most reliable cut-off level for GH secretion using the insulin tolerance test (ITT) in the transition from childhood to adulthood.

RESULTS

Ninety patients (22 female) with CO-GHD were retested using the ITT 1.1 +/- 1.1 years after discontinuation of therapy. Fifty-eight of 77 patients (75%) initially diagnosed with idiopathic GHD showed normalization of GH secretion. Thirteen patients were diagnosed with multiple pituitary hormone deficiency (MPHD) and diagnosis was reconfirmed in all of them, except for one patient. IGF-I levels of patients with persistent GHD were significantly lower (112 +/- 74 ng/ml [range 22-283] vs 245 +/- 107 ng/ml [range 31-505], p<0.01). IGF-I levels correlated positively with GH peak during ITT (r = 0.54, p <0.01), but the wide range of IGF-I levels shows that IGF-I alone cannot replace retesting in many cases. The best sensitivity and specificity scores were obtained when a GH cutoff level below 5.0 ng/ml for patients in the transition phase was used. ROC analysis demonstrates that ITT is a reliable test for evaluation of GH secretion in the transition phase (ROC-AUC 0.97).

CONCLUSIONS

Patients with CO-GHD should be retested after discontinuation of therapy to identify those who may profit from further replacement therapy. Patients with organic or genetic GHD or MPHD are likely to have persistent GHD, whereas 75% of our patients with idiopathic GHD showed normalization of growth hormone secretion. IGF-I levels alone are not reliable in the diagnosis of adult GHD in many cases. The best sensitivity and specificity scores were found when a GH cut-off level below 5.0 ng/ml was used in patients with GHD in the transition from childhood to adulthood.