High Frequency of Normal Response during GH Stimulation Tests in Patients with Ectopic Posterior Pituitary Gland: A Source of False-Negative Diagnosis of Pituitary Insufficiency

Trio-based whole exome sequencing in patients with ectopic posterior pituitary

Introduction

Ectopic posterior pituitary (EPP) is a rare congenital abnormality, sometimes associated with other midline defects, such as pituitary stalk interruption syndrome (PSIS), in which thin or absent pituitary stalk and anterior pituitary hypoplasia are combined to EPP. Most cases are sporadic, with few reports of familial cases, and many congenital hypopituitarism (CH) cases remain unsolved.

Objective

To search for candidate genes associated with this condition, we performed trio-based whole-exome sequencing (WES) on patients with EPP, including two familial cases.

Methods

This study included subjects with EPP and PSIS diagnosed by a simple MRI protocol (FAST1.2). We performed two distinct analyses in the trio-based WES. We looked for previously described genes associated with pituitary development. Next, we investigated the whole exome for variants inherited in a pattern consistent with a monogenic etiology.

Results

Ten families were evaluated; eight were composed of a child with EPP and healthy parents, one has two affected siblings, and one family has a son and mother with EPP. When analyzing the previously described candidate variants associated with pituitary development, we found variants in GLI2 and FGFR1 in three families. We also found six other variants of interest in three patients: KMT2A, GALR3, RTN4R, SEMA3A, NIPBL, and DSCAML1.

Conclusion

The analysis allowed us to find previously reported and not reported GLI2 variants, all inherited from healthy parents, which reinforces the incomplete penetrance pattern of GLI2 variants in the development of EPP and draws attention to possible future functional studies of those variants that have a recurrent expression in CH. We also found novel FGFR1 and SEMA3A variants that suggest an oligogenic mechanism in PSIS and EPP, as seen in patients with hypogonadotropic hypogonadism. We report the first case of a patient with Wiedemann-Steiner syndrome and PSIS, suggesting that the KMT2A gene may be related to pituitary development. Furthermore, the trios' analysis allowed us to find five other variants of interest. Future investigations may clarify the roles of these variants in the etiology of EPP and PSIS.

Whole exome sequencing in patients with ectopic posterior pituitary

Context

Ectopic posterior pituitary (EPP), a condition in which the posterior pituitary gland is displaced due to defective neuronal migration, is frequently associated with hypopituitarism. Genetic variants play a role, but many cases remain unexplained.

Objective

A large EPP cohort was studied to explore the importance of genetic variants and how they correlate with clinical findings.

Methods

Whole exome sequencing was performed on a discovery sample of 27 cases to identify rare variants. The variants that met the criteria for rarity and biological relevance, or that were previously associated with EPP (ROBO1 and HESX1), were then resequenced in the 27 cases plus a replication sample of 51 cases.

Results

We identified 16 different variants in 12 genes in 15 of the 78 cases (19.2%). Complete anterior pituitary deficiency was twice as common in cases with variants of interest compared to cases without variants (9/15; 60% vs. 19/63; 30.1%, respectively; Z test; p=0.06). Breech presentation was more frequent in the variant positive group (5/15 vs. 1/63; Z test; p= 0.003). Four cases had variants in ROBO1 and one in HESX1, genes previously associated with EPP. The ROBO1 p.S18* variant has not been reported previously; ROBO1 p.Q1227H has not been associated with EPP previously.

Conclusions

EPP cases with variants of interest identified in this study were more likely to present with severe clinical disease. Several variants were identified in genes not previously associated with EPP. Our findings confirm that EPP is a multigenic disorder. Future studies are needed to identify additional genes.

Differences between patients with isolated GH deficiency based on findings in brain magnetic resonance imaging

INTRODUCTION

Protocol for prescribing hormone replacement therapy in isolated growth hormone (GH) deficiency includes magnetic resonance imaging of the brain. There is controversy on the frequency of structural pituitary abnormalities and on the importance of abnormal MRI findings on prognosis and response to GH replacement.

METHODS

A descriptive, retrospective study of children of both sexes aged 0-14 years, who had undergone brain MRI, diagnosed with isolated GH deficiency at a tertiary hospital in the past 14 years, aimed at reporting the frequency of abnormal MRI findings in isolated GH deficiency, and to establish whether differences exist in height diagnosis and evolution according to MRI findings. MRI findings were also compared with the findings reported in healthy children in order to establish incidence.

RESULTS

96 patients were studied, of whom 74/96 (77%) reached adult age. Abnormal MRI findings were seen in 11.5% of them (8/11 of pituitary origin). No brain or pituitary tumor was seen in any case. Patients with abnormal images had a mean age at treatment start of 8 years, a target height of -0.8SD, and a final height of 1.04SD, while patients with normal MRI findings had an age at treatment start of 10 years old, a target height of -1.44SD, and a final height of -1.75SD, with statistically significant differences.

CONCLUSIONS

Patients with abnormal MRI findings show a more favorable response to GH replacement therapy.

PITUITARY STALK INTERRUPTION SYNDROME: REPORT OF TWO CASES AND LITERATURE REVIEW

Pituitary stalk interruption syndrome (PSIS) consisting of the triad: ectopic posterior pituitary (EPP), thin or absent pituitary stalk and anterior pituitary hypoplasia is a rare pituitary malformation with variable degrees of pituitary insufficiency, from isolated growth hormone deficiency to TSH, gonadotropin and ACTH deficiency which may occur in time, with normo, hyper or hypoprolactinemia and central diabetes insipidus in up to 10% of cases. Also, extrapituitary malformations have been described in some cases. Genetic defects were identified only in 5% of cases. MRI findings are considered predictive for the endocrine phenotype. We aim to describe two cases with PSIS without central diabetes insipidus, anosmia and extrapituitary malformations, except for minor head dysmorphic features. The first case was referred at the age of 4 years for short stature (-4SDS for height, bone age 2 years), diagnosed with severe GH deficiency and developed central hypothyroidism and hypoprolactinemia during five-years follow-up. The second case, a 26 year old male with birth asphyxia, cryptorchidism, poor growth in childhood and adolescence (-3 to -4 height SDS), absent puberty and normal adult height (-1.18 SDS; bone age 15.5 years and active growth plates) had GH, TSH, ACTH deficiency and low normal PRL levels. Increasing medical awareness on PSIS clinical and endocrine heterogeneity may help a more early and accurate diagnosis. Corroboration of neuroimaging and endocrine data will improve our knowledge and understanding and will create premises for molecular diagnosis, genetic counseling and a better patients' management.

Anterior Gray Matter Pituicytic Heterotopia with Monomorphic Anterior Pituitary Cells: A Variant of Nonsecretory Pituitary Adenoma Neuronal Choristoma? Report of a Rare Case and Review of the Literature

BACKGROUND

Mixed tumors of adenomatous and neuronal cells in the sellar region are an uncommon finding. The origins of these heterogeneous tumors are unknown, and management remains unsettled. We report a very rare case of anterior gray matter pituicytic heterotopia with monomorphic anterior pituitary cells that likely represents a variant of nonsecreting pituitary adenoma neuronal choristoma (PANCH) with no ganglion cells. We also review the current literature for the various clinical presentations of PANCH.

CASE DESCRIPTION

A 49-year-old female complaining of headache, blurred vision, and hair loss was found to have a nonsecretory sellar mass with compression of the optic chiasm on magnetic resonance imaging (MRI). The mass was excised via a transsphenoidal procedure. Histological analysis of tissue sections revealed heterotopic gray matter with reactive gliosis without ganglion cells or Herring bodies. Only 1 smear exhibited characteristics of a pituitary adenoma.

CONCLUSIONS

The overall findings were most consistent with a variant of PANCH. At a postoperative follow-up of 4.5 years, there was resolution of visual symptoms, and the residual sellar mass was stable on MRI. Neuronal choristoma is hypothesized to originate from embryonal pituitary or hypothalamus, or by differentiation from pituitary adenoma cells. Surgery is the cornerstone of management, and the clinical course appears to be similar to that of nonfunctioning pituitary adenoma in reported cases.

Pituitary stalk interruption syndrome: cause, clinical manifestations, diagnosis, and management

PURPOSE OF REVIEW

Pituitary stalk interruption syndrome (PSIS) is characterized by a thin or absent pituitary stalk, hypoplasia of the adenohypophysis, and ectopic neurohypophysis. PSIS manifestations include a wide spectrum of clinical phenotypes and pituitary hormone deficiencies of variable degree and timing of onset. In this review, recent advances with respect to the cause of PSIS, clinical characteristics leading to earlier diagnosis, and management are outlined.

RECENT FINDINGS

Diagnosis of PSIS is often delayed probably because clinical findings such as neonatal hypoglycemia, cholestasis, and/or micropenis as well as decreasing growth velocity are not appropriately and timely validated. Recently, molecular defects in various genes have been associated with PSIS albeit in a small number of cases. These findings suggest that PSIS belongs to the spectrum of holoprosencephaly-related defects. Phenotype-genotype discordance and the existence of asymptomatic carriers of a given molecular aberration indicate that penetrance may be modified favorably or unfavorably by the presence of other genetic and/or environmental factors.

SUMMARY

PSIS constitutes an antenatal anatomical defect. Neonatal hypoglycemia, cholestasis, and/or micropenis with or without growth deficit should raise the possibility of combined pituitary hormone deficiency, a life-threatening condition in cases of coexisting cortisol deficiency. It is important to search for molecular defects in all PSIS cases, as precise identification of the cause is a prerequisite for genetic counseling.