Aline P. Otto

FGFR1 and PROKR2 rare variants found in patients with combined pituitary hormone deficiencies

The genetic aetiology of congenital hypopituitarism (CH) is not entirely elucidated. FGFR1 and PROKR2 loss-of-function mutations are classically involved in hypogonadotrophic hypogonadism (HH), however, due to the clinical and genetic overlap of HH and CH; these genes may also be involved in the pathogenesis of CH. Using a candidate gene approach, we screened 156 Brazilian patients with combined pituitary hormone deficiencies (CPHD) for loss-of-function mutations in FGFR1 and PROKR2. We identified three FGFR1 variants (p.Arg448Trp, p.Ser107Leu and p.Pro772Ser) in four unrelated patients (two males) and two PROKR2 variants (p.Arg85Cys and p.Arg248Glu) in two unrelated female patients. Five of the six patients harbouring the variants had a first-degree relative that was an unaffected carrier of it. Results of functional studies indicated that the new FGFR1 variant p.Arg448Trp is a loss-of-function variant, while p.Ser107Leu and p.Pro772Ser present signalling activity similar to the wild-type form. Regarding PROKR2 variants, results from previous functional studies indicated that p.Arg85Cys moderately compromises receptor signalling through both MAPK and Ca2 + pathways while p.Arg248Glu decreases calcium mobilization but has normal MAPK activity. The presence of loss-of-function variants of FGFR1 and PROKR2 in our patients with CPHD is indicative of an adjuvant and/or modifier effect of these rare variants on the phenotype. The presence of the same variants in unaffected relatives implies that they cannot solely cause the phenotype. Other associated genetic and/or environmental modifiers may play a role in the aetiology of this condition.

Relatively high frequency of non‐synonymous GLI2 variants in patients with congenital hypopituitarism without holoprosencephaly

GLI2 is a downstream transcription factor in Sonic Hedgehog signalling, acting early in ventral forebrain and pituitary development. Heterozygous nonsense GLI2 mutations have been reported in patients with isolated or combined pituitary hormone deficiency (CPHD), with or without holoprosencephaly. The aim of this study was to screen for GLI2 mutations in a large cohort of patients with congenital GH deficiency.

Molecular analysis of brazilian patients with combined pituitary hormone deficiency and orthotopic posterior pituitary lobe reveals eight different PROP1 alterations with three novel mutations

Mutations in PROP1, HESX1 and LHX3 are associated with combined pituitary hormone deficiency (CPHD) and orthotopic posterior pituitary lobe (OPP).

A homozygous point mutation in the GH1 promoter (c.-223C>T) leads to reduced GH1 expression in siblings with isolated GH deficiency (IGHD)

CONTEXT Mutations in the GH1 promoter are a rare cause of isolated growth hormone deficiency (IGHD). OBJECTIVE To identify the molecular aetiology of a family with IGHD. DESIGN DNA sequencing, electromobility shift (EMSA) and luciferase reporter assays. SETTING University Hospital. PATIENTS Three siblings (2M) born to consanguineous parents presented with IGHD with normal pituitary on MRI. METHODS The GH1 proximal promoter, locus control region, five exons and four introns as well as GHRHR gene were sequenced in genomic DNA by Sanger method. DNA-protein interaction was evaluated by EMSA in nuclear extracts of GH3 pituitary cells. Dual-luciferase reporter assays were performed in cells transiently transfected with plasmids containing four different combinations of GH1 allelic variants (AV). RESULTS The patients harboured two homozygous variants (c.-185T>C and c.-223C>T) in the GH1 promoter within a highly conserved region and predicted binding sites for POU1F1/SP1 and SP1 respectively. The parents and brother were carriers and these variants were absent in 100 controls. EMSA demonstrated absent binding of GH3 nuclear extract to the c.-223C>T variant and normal binding of both POU1F1 protein and GH3 nuclear extract to the c.-185T>C variant. In contrast to GH1 promoter with AV only at c.-185, the GH1 promoter containing the AV only at c.-223 and at both positions drove significantly less expression of luciferase compared with the promoter containing either positions wild type in luciferase reporter assays. CONCLUSION To our knowledge, c.-223C>T is the first homozygous point mutation in the GH1 promoter that leads to short stature due to IGHD.

Autosomal recessive form of isolated growth hormone deficiency is more frequent than the autosomal dominant form in a Brazilian cohort.

BACKGROUND In most studies, the autosomal dominant (type II) form of isolated growth hormone deficiency (IGHD) has been more frequent than the autosomal recessive (type I) form. Our aim was to assess defects in the GH1 in short Brazilian children with different GH secretion status. SUBJECTS AND METHODS We selected 135 children with postnatal short stature and classified according to the highest GH peak at stimulation tests in: severe IGHD (peak GH≤3.3 μg/L, n=38, all with normal pituitary magnetic resonance imaging); GH peak between 3.3 and 10 μg/L (n=76); and GH peak >10 μg/L (n=21). The entire coding region of GH1 was sequenced and complete GH1 deletions were assessed by Multiplex Ligation Dependent Probe Amplification and restriction enzyme digestion. RESULTS Patients with severe IGHD had a higher frequency of consanguinity, were shorter, had lower levels of IGF-1 and IGFBP-3, and despite treatment with lower GH doses had a greater growth response than patients with GH peak ≥3.3 μg/L. Mutations were found only in patients with severe IGHD (GH peak<3.3 μg/L). Eight patients had autosomal recessive IGHD: Seven patients were homozygous for GH1 deletions and one patient was compound heterozygous for a GH1 deletion and the novel c.171+5G>C point mutation in intron 2, predicted to abolish the donor splice site. Only one patient, who was heterozygous for the c.291+1G>T mutation located at the universal donor splice site of intron 3 and predicts exon 3 skipping, had an autosomal dominant form. CONCLUSION Analysis of GH1 in a cohort of Brazilian patients revealed that the autosomal recessive form of IGHD was more common than the dominant one, and both were found only in severe IGHD.

Successful Pregnancies After Adequate Hormonal Replacement in Patients With Combined Pituitary Hormone Deficiencies

Context: Women with hypopituitarism have lower pregnancy rates after ovulation induction. Associated pituitary hormone deficiencies might play a role in this poorer outcome. Objective: We evaluated fertility treatment and pregnancy outcomes in five women with childhood-onset combined pituitary hormone deficiencies (CPHD). Patients and Methods: Five women with CPHD were referred for fertility treatment after adequacy of hormone replacement was determined. Patients were subjected to controlled ovarian stimulation (COS) for timed intercourse, intrauterine insemination, or in vitro fertilization, according to the presence or absence of other infertility factors (male or tubal). Results: All women became pregnant. The number of COS attempts until pregnancy was achieved varied between 1 and 5. The duration of COS resulting in at least one dominant follicle varied between 9 and 28 days, and total gonadotropin consumed varied between 1200 and 3450 IU. Two patients with severely suppressed basal gonadotropin levels since an early age had a cancelled COS cycle. All pregnancies were singleton except one (monochorionic twin gestation). The gestational ages at birth ranged from 35 weeks to 39 weeks and 4 days; three patients underwent cesarean section, and two had vaginal deliveries. Only one newborn was small for gestational age (delivered at 35 weeks). Conclusion: Adequate hormonal replacement prior to ovarian stimulation resulted in successful pregnancies in patients with childhood-onset CPHD, indicating that hormone replacement, including growth hormone, is an important step prior to fertility treatments in these patients.

Catch-Up Growth in Patients with Congenital or Acquired Growth Hormone Deficiency After GH Replacement: Clinical Features and Hypothalamic–Pituitary Imaging

Hypothalamic and pituitary disorders usually impair statural growth. These disorders may be either congenital or acquired with differences in clinical presentation. Growth failure is mainly related to growth hormone deficiency (GHD) that can be accompanied by other pituitary hormone deficiencies. The onset of clinical features may be insidious and unnoticed for years or decades. Therefore, it is important to periodically assess auxologic data such as height, growth velocity, bone maturation and evaluate hormonal levels related to hypothalamic–pituitary axis in these patients. Magnetic resonance imaging (MRI) greatly improved the study of central nervous system (CNS) disorders including the hypothalamic–pituitary region. Currently, it is an essential tool in the definition of the etiology of GHD. It can detect tumors that may require surgical intervention, and also provide insights into other causes of GHD. Catch up growth of congenital disorders is essentially dependent on hormone replacement. Even with an initial diagnosis of IGHD, attention should be given to the risk of the development of multiple pituitary hormone deficiencies. In addition to the hormonal deficiencies due to the acquired disorder themselves; their treatment (surgery, irradiation, chemotherapy) often leads to combined pituitary deficits. Growth responsiveness to rhGH has safety aspects of treatment which deserve additional discussion.