Clinical and genetic features of patients with multiple anterior pituitary hormone deficiency caused by mutations in the PROP1 gene; the efficacy of recombinant growth hormone therapy

Abstract

Rationale. One of the most common causes of multiple anterior pituitary hormone deficiency (MPHD) is genetic defects in the PROP1 gene. PROP1 deficiency leads to malfunction of somatotrophs, lactotrophs, thyrotrophs, corticotrophs, and gonadotrophs. Now, there is an opportunity to conduct large-scale population studies of patients with genetic MPHD, describe their clinical and genetic heterogeneity, and evaluate the efficacy of long-term therapy of these patients with a recombinant growth hormone (rGH).
 Aim. The study aim was to assess the spectrum of PROP1 gene mutations in the Russian population of MPHD patients, rate and expected age of hypopituitarism components, and efficacy of rGH therapy.
 Material and methods. We analyzed the data of 27 patients diagnosed with MPHD and genetically confirmed mutations in the PROP1 gene who were treated at the Institute of Pediatric Endocrinology of the Endocrinology Research Center (ERC) in 1978―2016. MPHD was diagnosed based on laboratory data and stimulatory tests characterizing the functional activity of the pituitary gland. The molecular genetic study was performed using high-performance parallel sequencing. We used a custom Ampliseq_HP primer panel developed at the Department of Hereditary Endocrinopathies of the ERC, which included coding regions of the following genes: ARNT2, GH1, GHRH, GHRHR, GHSR, GLI2, HESX1, LHX3, LHX4, OTX2, PAX6, POU1F1, PROP1, SHH, SOX2, and SOX3. All patients received rGH therapy at a growth-stimulating dose from the time of GH deficiency diagnosis until final height completion. We evaluated the efficacy of therapy by comparing the achieved final height with the genetically expected one.
 Results. Non-familial cases prevailed (N=23) in the study cohort of patients with MPHD caused by mutations in the PROP1 gene; only two patients were monochorionic twin sisters; the other two patients were siblings. An analysis of the distribution of PROP1 gene mutations revealed a hot-point mutation c.301_302delAG in 24 patients (89%, 95% CI 71%; 98%). A mutation in the c.150delA locus occurred in 11 patients (41%, 95% CI 22%; 61%). Two patients had other mutations (c.629delC and c.43_49delGGGCGAG). Total GH deficiency was detected in all patients. The rate of secondary hypothyroidism (SHT) in patients of the study sample was 78% (95% CI 58%; 91%) at the time of diagnosis of GH deficiency and 100% (95% CI 81%; 100%) at the time of final height. The rate of secondary hypogonadism (SHG) at the time of final height was 100% (95% CI 81%; 100%), and the rate of secondary hypocorticism (SHC) was 41% (95% CI 22%; 61%). The normal level of prolactin was detected in 83% (95% CI 65%; 94%) of patients. At the time of growth plate closure, patients receiving rGH therapy at the growth-stimulating dose achieved the genetically expected final height.
 Conclusion. According to our findings, the most common mutation in the PROP1 gene is a deletion of AG nucleotides in the 101 codon (c.301_302 delAG), which is found in 89% (95% CI 71%; 98) patients. Patients with MPHD caused by mutations in the PROP1 gene have total GH deficiency and are diagnosed with secondary hypothyroidism and secondary hypogonadism in 100% of cases. The possibility of delayed manifestation of hypopituitarism components requires regular screening of tropic hormone levels for the timely start of substitution therapy and prevention of life-threatening conditions. rGH therapy is highly effective for GH deficiency caused by PROP1 gene mutations and allows patients to achieve the genetically expected height in the case of early diagnosis of growth hormone deficiency.