Fernanda A. Correa

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.

Genome-wide screening of copy number variants in children born small for gestational age reveals several candidate genes involved in growth pathways

BACKGROUND The etiology of prenatal-onset short stature with postnatal persistence is heterogeneous. Submicroscopic chromosomal imbalances, known as copy number variants (CNVs), may play a role in growth disorders. OBJECTIVE To analyze the CNVs present in a group of patients born small for gestational age (SGA) without a known cause. PATIENTS AND METHODS A total of 51 patients with prenatal and postnatal growth retardation associated with dysmorphic features and/or developmental delay, but without criteria for the diagnosis of known syndromes, were selected. Array-based comparative genomic hybridization was performed using DNA obtained from all patients. The pathogenicity of CNVs was assessed by considering the following criteria: inheritance; gene content; overlap with genomic coordinates for a known genomic imbalance syndrome; and overlap with CNVs previously identified in other patients with prenatal-onset short stature. RESULTS In 17 of the 51 patients, 18 CNVs were identified. None of these imbalances has been reported in healthy individuals. Nine CNVs, found in eight patients (16%), were categorized as pathogenic or probably pathogenic. Deletions found in three patients overlapped with known microdeletion syndromes (4q, 10q26, and 22q11.2). These imbalances are de novo, gene rich and affect several candidate genes or genomic regions that may be involved in the mechanisms of growth regulation. CONCLUSION Pathogenic CNVs in the selected patients born SGA were common (at least 16%), showing that rare CNVs are probably among the genetic causes of short stature in SGA patients and revealing genomic regions possibly implicated in 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.

Avaliação dos critérios diagnósticos hormonais da forma não clássica da deficiência da 21-hidroxilase através do estudo molecular do gene CYP21A2

Diagnosis of the nonclassical form of 21-hydroxylase deficiency (NC-21OH) is based on clinical hyperandrogenism and basal 17-hydroxyprogesterone (17OHP) levels >5ng/mL or >10ng/mL after ACTH-stimulation. We present two children with precocious pubarche and a hormonal diagnosis of NC-21OH, whose molecular study of the CYP21A2 gene confirmed the diagnosis in just one case. After that, we re-evaluated the diagnosis of 58 patients with ACTH-stimulated 17OHP levels >10ng/mL with molecular studies of CYP21A2 gene. Only 37 (67%) of these patients had mutations detected in both alleles: basal 17OHP levels were >5ng/mL in 70%, normal in 11% and between 2 and 5ng/mL in the remaining patients. The lowest ACTH-stimulated 17OHP level in this group was 17ng/mL. We then analyzed 59 obligate carriers for 21-hydroxylase deficiency and found two asymptomatic subjects with ACTH-stimulated 17OHP levels of 11 and 15ng/mL, respectively. Based on these findings, we suggest that the current cut-off value for ACTH-stimulated 17OHP level overestimates the diagnosis of NC-21OH.

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.

Pathogenic copy number variants in patients with congenital hypopituitarism associated with complex phenotypes

The aetiology of congenital hypopituitarism (CH) is unknown in most patients. Rare copy number variants (CNVs) have been implicated as the cause of genetic syndromes with previously unknown aetiology. Our aim was to study the presence of CNVs and their pathogenicity in patients with idiopathic CH associated with complex phenotypes.

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.

Growth hormone deficiency with advanced bone age: phenotypic interaction between GHRH receptor and CYP21A2 mutations diagnosed by sanger and whole exome sequencing

Isolated growth hormone deficiency (IGHD) is the most common pituitary hormone deficiency and, clinically, patients have delayed bone age. High sequence similarity between CYP21A2 gene and CYP21A1P pseudogene poses difficulties for exome sequencing interpretation. A 7.5 year-old boy born to second-degree cousins presented with severe short stature (height SDS -3.7) and bone age of 6 years. Clonidine and combined pituitary stimulation tests revealed GH deficiency. Pituitary MRI was normal. The patient was successfully treated with rGH. Surprisingly, at 10.8 years, his bone age had advanced to 13 years, but physical exam, LH and testosterone levels remained prepubertal. An ACTH stimulation test disclosed a non-classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency explaining the bone age advancement and, therefore, treatment with cortisone acetate was added. The genetic diagnosis of a homozygous mutation in GHRHR (p.Leu144His), a homozygous CYP21A2 mutation (p.Val282Leu) and CYP21A1P pseudogene duplication was established by Sanger sequencing, MLPA and whole-exome sequencing. We report the unusual clinical presentation of a patient born to consanguineous parents with two recessive endocrine diseases: non-classic congenital adrenal hyperplasia modifying the classical GH deficiency phenotype. We used a method of paired read mapping aided by neighbouring mis-matches to overcome the challenges of exome-sequencing in the presence of a pseudogene.