Clinical and therapeutic implications of cavernous sinus invasion in pituitary adenomas

Invasion of the cavernous sinus by pituitary adenomas impedes complete surgical resection, compromises biochemical remission, and increases the risk of further tumor recurrence. Accurate preoperative MRI-based diagnosis or intraoperative direct inspection of cavernous sinus invasion are essential for optimal surgical planning and for tailoring postoperative therapeutic strategies, depending on whether a total resection has been achieved, or tumoral tissue has been left in surgically inaccessible locations. The molecular mechanisms underlying the invasive behavior of pituitary adenomas remain poorly understood, hindering the development of targeted therapies. Some studies have identified genes overexpressed in pituitary adenomas invading the cavernous sinus, offering insights into the acquisition of invasive behavior. Their main limitation however lies in comparing purely intrasellar specimens obtained from invasive and non-invasive adenomas. Further, precise anatomical knowledge of the medial wall of the cavernous sinus is crucial for grasping the mechanisms of invasion. Recently, alongside the standard intrasellar surgery, extended endoscopic intracavernous surgical procedures with systematic selective resection of the medial wall of the cavernous sinus have shown promising results for invasive secreting pituitary adenomas. The first- and second-generation somatostatin agonist ligands and cabergoline are used with variable efficacy to control secretory activity and/or growth of intracavernous remnants. Tumor regrowth usually requires surgical reintervention, sometimes combined with radiotherapy or radiosurgery which is applied despite their benign nature. Unraveling the molecular pathways driving invasive behavior of pituitary adenomas and their tropism to the cavernous sinuses is the key for developing efficient innovative treatment modalities that could reduce the need for repeated surgery or radiotherapy.

Anatomy of the medial wall of the cavernous sinus: A systematic review of the literature

The existence, composition, and continuity of the medial wall of the cavernous sinus (MWCS) have been extensively studied and debated. However, the precise nature of this membrane remains unknown. Understanding the anatomical characteristics of the MWCS is crucial, notably in relation to pituitary adenomas, which often invade the cavernous sinus. Indeed, surgical treatment of those tumors is frequently incomplete because of such invasion. The anatomical and molecular basis of the peculiar and often lateralized tropism of adenomatous cells to the cavernous sinus is not yet understood and it has been suggested repeatedly that the MWCS is physiologically frail. During the past three decades, there have been several conflicting accounts of the existence, composition, and continuity of this medial wall, but methodological differences and varying definitions could have contributed to the current lack of consensus regarding it. The aim of this systematic review was to summarize previously published data concerning the existence, anatomy, composition, and continuity of the MWCS.

Diabetes insipidus: Vasopressin deficiency…

Diabetes insipidus is a disorder characterized by hypo-osmotic polyuria secondary to abnormal synthesis, regulation, or renal action of antidiuretic hormone. Recently, an expert group, with the support of patient associations, proposed that diabetes insipidus be renamed to avoid confusion with diabetes mellitus. The most common form of diabetes insipidus is secondary to a dysfunction of the neurohypophysis (central diabetes insipidus) and would be therefore named â€̃vasopressin deficiency’. The rarer form, which is linked to renal vasopressin resistance (nephrogenic diabetes insipidus), would then be named â€̃vasopressin resistance’. The etiology of diabetes insipidus is sometimes clear, in the case of a neurohypophyseal cause (tumoral or infiltrative damage) or a renal origin, but in some cases diabetes insipidus can be difficult to distinguish from primary polydipsia, which is characterized by consumption of excessive quantities of water without any abnormality in regulation or action of antidiuretic hormone. Apart from patients’ medical history, physical examination, and imaging of the hypothalamic-pituitary region, functional tests such as water deprivation or stimulation of copeptin by hyperosmolarity (induced by infusion of hypertonic saline) can be proposed in order to distinguish between these different etiologies. The treatment of diabetes insipidus depends on the underlying etiology, and in the case of a central etiology, is based on the administration of desmopressin which improves patient symptoms but does not always result in an optimal quality of life. The cause of this altered quality of life may be oxytocin deficiency, oxytocin being also secreted from the neurohypophysis, though this has not been fully established. The possibility of a new test using stimulation of oxytocin to identify alterations in oxytocin synthesis is of interest and would allow confirmation of a deficiency in those patients presenting with diabetes insipidus linked to neurohypophyseal dysfunction.

KDM1A genotyping and expression in 146 sporadic somatotroph pituitary adenomas

IMPORTANCE

A paradoxical increase of growth hormone (GH) following oral glucose load has been described in ∼30% of patients with acromegaly and has been related to the ectopic expression of the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) in somatotropinomas. Recently, we identified germline pathogenic variants and somatic loss of heterozygosity of lysine demethylase 1A (KDM1A) in patients with GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome. The ectopic expression of GIPR in both adrenal and pituitary lesions suggests a common molecular mechanism.

OBJECTIVE

We aimed to analyze KDM1A gene sequence and KDM1A and GIPR expressions in somatotroph pituitary adenomas.

SETTINGS

We conducted a cohort study at university hospitals in France and in Italy. We collected pituitary adenoma specimens from acromegalic patients who had undergone pituitary surgery. We performed targeted exome sequencing (gene panel analysis) and array-comparative genomic hybridization on somatic DNA derived from adenomas and performed droplet digital PCR on adenoma samples to quantify KDM1A and GIPR expressions.

RESULTS

One hundred and forty-six patients with sporadic acromegaly were studied; 72.6% presented unsuppressed classical GH response, whereas 27.4% displayed a paradoxical rise in GH after oral glucose load. We did not identify any pathogenic variant in the KDM1A gene in the adenomas of these patients. However, we identified a recurrent 1p deletion encompassing the KDM1A locus in 29 adenomas and observed a higher prevalence of paradoxical GH rise (P = .0166), lower KDM1A expression (4.47 ± 2.49 vs 8.56 ± 5.62, P < .0001), and higher GIPR expression (1.09 ± 0.92 vs 0.43 ± 0.51, P = .0012) in adenomas from patients with KDM1A haploinsufficiency compared with those with 2 KDM1A copies.

CONCLUSIONS AND RELEVANCE

Unlike in GIP-dependent primary bilateral macronodular adrenal hyperplasia, KDM1A genetic variations are not the cause of GIPR expression in somatotroph pituitary adenomas. Recurrent KDM1A haploinsufficiency, more frequently observed in GIPR-expressing adenomas, could be responsible for decreased KDM1A function resulting in transcriptional derepression on the GIPR locus.

Prevalence and clinical correlations of SF3B1 variants in lactotroph tumours

OBJECTIVE

A somatic mutational hotspot in the SF3B1 gene was reported in lactotroph tumours. The aim of our study was to examine the prevalence of driver SF3B1 variants in a multicentre independent cohort of patients with lactotroph tumours and correlate with clinical data.

DESIGN AND METHODS

This was a retrospective, multicentre study involving 282 patients with lactotroph tumours (including 6 metastatic lactotroph tumours) from 8 European centres. We screened SF3B1 exon 14 hotspot for somatic variants using Sanger sequencing and correlated with clinicopathological data.

RESULTS

We detected SF3B1 variants in seven patients with lactotroph tumours: c.1874G > A (p.Arg625His) (n = 4, 3 of which metastatic) and a previously undescribed in pituitary tumours variant c.1873C > T (p.Arg625Cys) (n = 3 aggressive pituitary tumours). In two metastatic lactotroph tumours with tissue available, the variant was detected in both primary tumour and metastasis. The overall prevalence of likely pathogenic SF3B1 variants in lactotroph tumours was 2.5%, but when we considered only metastatic cases, it reached the 50%. SF3B1 variants correlated with significantly larger tumour size; higher Ki67 proliferation index; multiple treatments, including radiotherapy and chemotherapy; increased disease-specific death; and shorter postoperative survival.

CONCLUSIONS

SF3B1 variants are uncommon in lactotroph tumours but may be frequent in metastatic lactotroph tumours. When present, they associate with aggressive tumour behaviour and worse clinical outcome.

Clinical, pathophysiologic, genetic and therapeutic progress in Primary Bilateral Macronodular Adrenal Hyperplasia

Patients with primary bilateral macronodular adrenal hyperplasia (PBMAH) usually present bilateral benign adrenocortical macronodules at imaging and variable levels of cortisol excess. PBMAH is a rare cause of primary overt Cushing's syndrome, but may represent up to one third of bilateral adrenal incidentalomas with evidence of cortisol excess. The increased steroidogenesis in PBMAH is often regulated by various G-protein coupled receptors aberrantly expressed in PBMAH tissues; some receptor ligands are ectopically produced in PBMAH tissues creating aberrant autocrine/paracrine regulation of steroidogenesis. The bilateral nature of PBMAH and familial aggregation, led to the identification of germline heterozygous inactivating mutations of the ARMC5 gene, in 20-25% of the apparent sporadic cases and more frequently in familial cases; ARMC5 mutations/pathogenic variants can be associated with meningiomas. More recently, combined germline mutations/pathogenic variants and somatic events inactivating the KDM1A gene were specifically identified in patients affected by GIP-dependent PBMAH. Functional studies demonstrated that inactivation of KDM1A leads to GIP-receptor (GIPR) overexpression and over or down-regulation of other GPCRs. Genetic analysis is now available for early detection of family members of index cases with PBMAH carrying identified germline pathogenic variants. Detailed biochemical, imaging, and co-morbidities assessment of the nature and severity of PBMAH is essential for its management. Treatment is reserved for patients with overt or mild cortisol/aldosterone or other steroid excesses taking in account co-morbidities. It previously relied on bilateral adrenalectomy; however recent studies tend to favor unilateral adrenalectomy, or less frequently, medical treatment with cortisol synthesis inhibitors or specific blockers of aberrant GPCR.

Loss of KDM1A in GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome: a multicentre, retrospective, cohort study

BACKGROUND

GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome is caused by aberrant expression of the GIP receptor in adrenal lesions. The bilateral nature of this disease suggests germline genetic predisposition. We aimed to identify the genetic driver event responsible for GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome.

METHODS

We conducted a multicentre, retrospective, cohort study at endocrine hospitals and university hospitals in France, Canada, Italy, Greece, Belgium, and the Netherlands. We collected blood and adrenal samples from patients who had undergone unilateral or bilateral adrenalectomy for GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome. Adrenal samples from patients with primary bilateral macronodular adrenal hyperplasia who had undergone an adrenalectomy for overt or mild Cushing's syndrome without evidence of food-dependent cortisol production and those with GIP-dependent unilateral adrenocortical adenomas were used as control groups. We performed whole genome, whole exome, and targeted next generation sequencing, and copy number analyses of blood and adrenal DNA from patients with familial or sporadic disease. We performed RNA sequencing on adrenal samples and functional analyses of the identified genetic defect in the human adrenocortical cell line H295R.

FINDINGS

17 patients with GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome were studied. The median age of patients was 43·3 (95% CI 38·8-47·8) years and most patients (15 [88%]) were women. We identified germline heterozygous pathogenic or most likely pathogenic variants in the KDM1A gene in all 17 patients. We also identified a recurrent deletion in the short p arm of chromosome 1 harboring the KDM1A locus in adrenal lesions of these patients. None of the 29 patients in the control groups had KDM1A germline or somatic alterations. Concomitant genetic inactivation of both KDM1A alleles resulted in loss of KDM1A expression in adrenal lesions. Global gene expression analysis showed GIP receptor upregulation with a log2 fold change of 7·99 (95% CI 7·34-8·66; p=4·4 × 10^-125), and differential regulation of several other G protein-coupled receptors in GIP-dependent primary bilateral macronodular hyperplasia samples compared with control samples. In vitro pharmacological inhibition and inactivation of KDM1A by CRISPR-Cas9 genome editing resulted in an increase of GIP receptor transcripts and protein in human adrenocortical H295R cells.

INTERPRETATION

We propose that GIP-dependent primary bilateral macronodular adrenal hyperplasia with Cushing's syndrome results from a two-hit inactivation of KDM1A, consistent with the tumour suppressor gene model of tumorigenesis. Genetic testing and counselling should be offered to these patients and their relatives.

FUNDING

Agence Nationale de la Recherche, Fondation du Grand défi Pierre Lavoie, and the French National Cancer Institute.

Non-classic cytochrome P450 oxidoreductase deficiency strongly linked with menstrual cycle disorders and female infertility as primary manifestations

STUDY QUESTION

Can cytochrome P450 oxidoreductase deficiency (PORD) be revealed in adult women with menstrual disorders and/or infertility?

SUMMARY ANSWER

PORD was biologically and genetically confirmed in five adult women with chronically elevated serum progesterone (P) who were referred for oligo-/amenorrhea and/or infertility.

WHAT IS KNOWN ALREADY

PORD is an autosomal recessive disease typically diagnosed in neonates and children with ambiguous genitalia and/or skeletal abnormalities. It is responsible for the decreased activity of several P450 enzymes, including CYP21A2, CYP17A1 and CYP19A1, that are involved in adrenal and/or gonadal steroidogenesis. Little is known about the optimal way to investigate and treat patients with adult-onset PORD.

STUDY DESIGN, SIZE, DURATION

In this series, we report five adult females who were evaluated in three tertiary endocrine reproductive departments between March 2015 and September 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Five women aged 19-38 years were referred for unexplained oligo-/amenorrhea and/or infertility. Genetic testing excluded 21-hydroxylase deficiency (21OH-D), initially suspected due to the increased 17-hydroxyprogesterone (17-OHP) levels. Extensive phenotyping, steroid profiling by mass spectrometry, pelvic imaging and next-generation sequencing of 84 genes involved in gonadal and adrenal disorders were performed in all patients. IVF followed by frozen embryo transfer (ET) under glucocorticoid suppression therapy was performed for two patients.

MAIN RESULTS AND THE ROLE OF CHANCE

All patients had oligomenorrhea or amenorrhea. None had hyperandrogenism. Low-normal serum estradiol (E2) and testosterone levels contrasted with chronically increased serum P and 17-OHP levels, which further increased after adrenocorticotrophic hormone (ACTH) administration. Despite excessive P, 17OH-P and 21-deoxycortisol rise after ACTH stimulation suggesting non-classic 21OH-D, CYP21A2 sequencing did not support this hypothesis. Basal serum cortisol levels were low to normal, with inadequate response to ACTH in some women, suggesting partial adrenal insufficiency. All patients harbored rare biallelic POR mutations classified as pathogenic or likely pathogenic according to the American College of Medical Genetics and Genomics standards. Pelvic imaging revealed bilateral ovarian macrocysts in all women. IVF was performed for two women after retrieval of a normal oocyte number despite very low E2 levels during ovarian stimulation. Frozen ET under glucocorticoid suppression therapy led to successful pregnancies.

LIMITATIONS, REASONS FOR CAUTION

The number of patients described here is limited and these data need to be confirmed on a larger number of women with non-classic PORD.

WIDER IMPLICATIONS OF THE FINDINGS

The diagnosis of PORD must be considered in infertile women with chronically elevated P and 17OH-P levels and ovarian macrocysts. Differentiation of this entity from non-classic 21OH-D is important, as the multiple enzyme deficiency requires a specific management. Successful fertility induction is possible by IVF, providing that P levels be sufficiently suppressed by glucocorticoid therapy prior to implantation.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was used for this study. There are no potential conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Germline CDKN1B Loss-of-Function Variants Cause Pediatric Cushing's Disease With or Without an MEN4 Phenotype

CONTEXT

Germline loss-of-function CDKN1B gene variants cause the autosomal dominant syndrome of multiple endocrine neoplasia type 4 (MEN4). Even though pituitary neuroendocrine tumors are a well-known component of the syndrome, only 2 cases of Cushing's disease (CD) have so far been described in this setting.

AIM

To screen a large cohort of CD patients for CDKN1B gene defects and to determine their functional effects.

PATIENTS

We screened 211 CD patients (94.3% pediatric) by germline whole-exome sequencing (WES) only (n = 157), germline and tumor WES (n = 27), Sanger sequencing (n = 6), and/or germline copy number variant (CNV) analysis (n = 194). Sixty cases were previously unpublished. Variant segregation was investigated in the patients' families, and putative pathogenic variants were functionally characterized.

RESULTS

Five variants of interest were found in 1 patient each: 1 truncating (p.Q107Rfs*12) and 4 nontruncating variants, including 3 missense changes affecting the CDKN1B protein scatter domain (p.I119T, p.E126Q, and p.D136G) and one 5' untranslated region (UTR) deletion (c.-29_-26delAGAG). No CNVs were found. All cases presented early (10.5 ± 1.3 years) and apparently sporadically. Aside from colon adenocarcinoma in 1 carrier, no additional neoplasms were detected in the probands or their families. In vitro assays demonstrated protein instability and disruption of the scatter domain of CDKN1B for all variants tested.

CONCLUSIONS

Five patients with CD and germline CDKN1B variants of uncertain significance (n = 2) or pathogenic/likely pathogenic (n = 3) were identified, accounting for 2.6% of the patients screened. Our finding that germline CDKN1B loss-of-function may present as apparently sporadic, isolated pediatric CD has important implications for clinical screening and genetic counselling.

SAT-010 Non-Classic POR Deficiency as a Cause of Menstrual Disorders & Infertility

P450 oxidoreductase deficiency (PORD) is an autosomal recessive disease caused by bi-allelic mutations of the POR gene. It is responsible for decreased activity of several P450 enzymes including CYP21A2, CYP17A1 and CYP19A1 that are involved in adrenal and/or gonadal steroidogenesis. PORD is typically diagnosed in neonates and children with ambiguous genitalia and/or skeletal abnormalities. Adult-onset PORD has been very seldom reported and little is known about the optimal way to investigate and treat such patients. In this series, we report five women aged 19-38 years, who were referred for unexplained oligo-/amenorrhea and/or infertility. Genetic testing excluded 21-hydroxylase deficiency (21OH-D), initially suspected due to increased 17-hydroxyprogesterone (17-OHP) levels. Extensive phenotyping, steroid profile by mass spectrometry, pelvic imaging and next-generation sequencing of 84 genes involved in gonadal and adrenal disorders were performed in all patients. In Vitro Fertilization (IVF) followed by frozen embryo transfer under glucocorticoid suppression therapy was performed in two patients. All patients had oligomenorrhea or amenorrhea. None had hyperandrogenism. Low-normal serum estradiol (E2) and testosterone levels contrasted with chronically increased serum progesterone (P) and 17-OHP levels, which further increased after ACTH administration. Despite excessive P, 17OH-P and 21-deoxycortisol rises after ACTH stimulation suggesting non-classic 21-hydroxylase deficiency, CYP21A2 sequencing did not support this hypothesis. Basal serum cortisol levels were low to normal, with inadequate response to ACTH in some women, suggesting partial adrenal insufficiency. Pelvic imaging revealed bilateral ovarian macrocysts in all women. All patients were found to harbor rare bi-allelic POR mutations classified as pathogenic according to American College of Medical Genetics standards. IVF was performed in two women after retrieval of a normal oocyte number despite very low E2 levels during controlled ovarian hyperstimulation. Frozen embryo transfer under glucorticoid suppression therapy led to successful pregnancies. These observations suggest that diagnosis of PORD must be considered in infertile women with chronically elevated P and 17OH-P levels and ovarian macrocysts. Differentiation of this entity from non-classic 21-hydroxylase deficiency is important, as the multiple enzyme deficiency requires a specific management. Successful fertility induction is possible by IVF, providing that P levels be sufficiently suppressed by glucocorticoid therapy prior to implantation.

Unilateral nonhaemorrhagic adrenal infarction as a cause of abdominal pain during pregnancy

Adrenal infarction is usually associated with bilateral adrenal hemorrhage in the setting of antiphospholipid syndrome or hemodynamic variation. Few cases of unilateral nonhemorrhagic adrenal infarction (NHAI) have been described in the literature. Here, we report a case occurring during pregnancy. A 30-year-old woman presented at 32 weeks of gestation with sudden-onset right abdominal pain and contractions. Unilateral adrenal infarction was diagnosed following computed tomography (CT). It showed an enlarged right adrenal, without hyperenhancement. Because of persisting contractions, despite medical care, she delivered a healthy, albeit premature, girl. Abdominal pain decreased right after delivery. Three month later, CT imaging showed atrophy of the right adrenal and a normal left adrenal. The patient's adrenal hormonal function was normal. Accurate diagnosis of NHAI remains difficult as its clinical presentation is not specific. It can only be performed with adrenal imaging. Magnetic resonance imaging shows diffuse enlargement of one or both adrenals and an edema on T2-weighted images. Anticoagulation therapy may be discussed. Patients should be evaluated between 3 and 6 months after the event to assess adrenal size and function. In summary, NHAI during pregnancy is probably underdiagnosed and obstetricians should be aware of this or diagnostic difficulty.

OR24-6 Non-syndromic Cushing's Disease Due To CDKN1B Mutations: Novel Mutations And Phenotypic Features In A Large Pediatric Cohort

Introduction: Germline loss-of-function mutations in the CDKN1B gene underlie multiple endocrine neoplasia type 4 (MEN4), an infrequent and clinically heterogeneous autosomal dominant syndrome with incomplete penetrance. MEN4 encompasses various neuroendocrine tumors and other neoplasms, including pituitary adenomas. Despite the central role of the CDKN1B protein in corticotroph cell function and the finding that Cdkn1b KO mice develop Pomc-positive pituitary adenomas, only two cases of Cushing’s disease (CD) have so far been described in the setting of MEN4. We aimed to determine the frequency of CDKN1B gene defects in a cohort of pediatric CD patients, and to functionally validate our findings. Methods: We studied 203 pediatric CD patients referred to our center between 1997-2018; 60.6% were female. The median age was 10.8 (interquartile range: 8-13.8) years at disease onset, and 12.8 (10.3-15.5) years at diagnosis. Ten cases had familial or simplex presentation and 103 cases were sporadic. Ninety-eight patients underwent whole-exome sequencing of germline DNA only (n=70) or germline and tumor DNA (n=28); 105 patients were screened by Sanger sequencing. Germline copy number variations (CNVs) were searched for in 197 cases by droplet digital PCR. Loss of heterozygosity (LOH) and CDKN1B immunohistochemistry (IHC) were analyzed in the tumors and inheritance of the variants was investigated. Variants of interest were cloned into expression plasmids and overexpressed in AtT-20/D16v-F2 (mouse corticotropinoma) cells. The expression of CDKN1B protein variants and their impact on POMC quantification were analyzed by Western blot. Results: Four heterozygous germline CDKN1B (NM_004064.4) rare variants were identified in one patient each: c.-32_-29delGAGA, c.320delA (p.Q107Rfs*12), c.356T>C (p.I119T), and c.407A>G (p.D136G). No CNVs or somatic variants were found. Variants c.356T>C and c.-32_-29delGAGA have been reported in MEN4 kindreds. Three c.320delA carriers related to our patient were found; one of them died of a colon adenocarcinoma, which displayed LOH. This tumor represents a novel MEN4 component. In the rest of the cases, variant inheritance could not be determined, and there was no LOH in the corticotropinomas. IHC showed partial (p.D136G) or almost complete (c.-32_-29delGAGA and c.356T>C) loss of CDKN1B nuclear staining in corticotropinomas. All variants were detected at the protein level, but c.320delA resulted in a protein ~10 kDa smaller than the wild type, and c.356T>C caused a slight delay in migration. POMC expression was 1.6±0.1 times higher when overexpressing c.320delA, compared with empty vector (P=0.049). Conclusion: MEN4 explains 2% of the CD cases in our cohort. CDKN1B mutations may lead to apparently isolated CD in young patients, a phenotypic variant that should be noted, given its implications for clinical screening and genetic counseling.

SUN-038 Role Of The Satb 1 Gene In Growth Across Species: Findings In A Cohort Of Patients With Short Stature And In A Knockout Zebrafish Model

Background: Short stature is a common pediatric disorder, affecting 3% of the population; however, the identification of its cause is limited by its largely variable clinical presentation and genetic heterogeneity. Identification of novel genetic causes of short stature is of great importance to customize the therapeutic approach of this entity. The especial AT-rich sequence binding protein1 gene (SATB1) encodes a chromatin organizer with important roles in cell growth and immunosuppression. SATB1 is highly expressed in the pituitary gland, where it regulates the differentiation of PIT1 positive cells. Indeed, the conditional knockout of Satb1 in the mouse pituitary decreases growth hormone expression, leading to reduced growth. Aim: To investigate the putative role of SATB1 in growth in a cohort of individuals with short stature and in a zebrafish knockout (KO) model. Methods: We obtained germline DNA samples from a cohort of 287 Brazilian patients diagnosed with short stature (height <2 SDS for age and sex), including 52 patients small for gestational age (SGA), 5 cases with growth hormone deficiency (GHD), 10 cases with syndromic short stature and 220 cases with idiopathic short stature. All cases were screened for SATB1 copy number variations (CNVs) using droplet digital PCR, and 190 cases were screened for mutations via Sanger sequencing. In silico predictions were retrieved from the Varsome browser. All variants were annotated to RefSeq NM_002971.5. Using CRISPR-Cas9, we generated two lines of zebrafish satb1 bearing frameshift mutations; both lines were crossed to obtain full KOs. Growth was monitored from 3 to 12 weeks post-fertilization (wpf) and expression of pituitary hormones was analyzed at 6 wpf by quantitative PCR. Results: No variants predicted as damaging were found in the short stature cohort. Nevertheless, variants of uncertain significance (VUS, mostly intronic) were found in 11% of our cohort, in which 57% of the individuals that carry a VUS presented familial short stature while 43% were non-familial. Interestingly, the variant c.515+112G>A was identified in 3/33 (9.1%) of SGA patients, but only in 2/143 (1.4%) of ISS patients. No CNVs were observed. In the zebrafish model, satb1 knockout led to significantly smaller size at 3 wpf, compared with heterozygous and wild type controls (median standard length: 6.6, 7.4, and 7.8 cm, and mean weight: 2.7, 4.3, and 4.6 mg, respectively, P<0.05 for all comparisons). At 6 wpf, we identified a trend for lower gh1 expression in the KOs vs. heterozygous zebrafish (relative quantification: 0.68 vs. 1.79, P=0.06). Conclusion: Our results support a role for SATB1 in regulating growth hormone production across species. Although loss of SATB1 function could theoretically lead to growth hormone deficiency in humans, defects in this gene do not seem to play a crucial role in the height of individuals with short stature.