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Keywords:

  • anterior pituitary aplasia;
  • hypopituitarism;
  • array-CGH;
  • cryptic deletion

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Anterior pituitary aplasia (APA) is a very rare cause of congenital-onset multiple pituitary hormone deficiency (CO-MPHD). We report on molecular analysis and clinical follow-up of three previously reported cases of APA [Scommegna et al., 2004], who share a characteristic physical and neuropsychological profile. Mutation analysis of genes encoding transcription factors involved in pituitary development (PROP1, POUF1, HESX1, LHX3, and LHX4) did not demonstrate a any mutation. In order to identify the genetic cause underlying the phenotypes we performed an array-based comparative genomic hybridization (array-CGH), which showed a cryptic interstitial deletion of 9p (200 kb), including the TEK and MOBKL2B, in one patient. Although an apparently identical deletion was carried by the clinically normal father, we assumed that the patient's phenotype might be due to a recessive mutation in the other allele. However, sequence analysis of exons and splice junctions of these genes did not detect pathogenic or predisposing variants in the three patients. We suggest that the constellation of clinical signs in these patients constitutes a previously undescribed syndrome, whose genetic cause has yet to be identified. © 2012 Wiley Periodicals, Inc.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Congenital-onset multiple pituitary hormone deficiency (CO-MPHD) is a rare, life-threatening condition. It may be difficult to diagnose, as clinical manifestations usually occur early in the neonatal period with very severe, but non-specific symptoms, such as respiratory distress, hypoglycemia, seizures, prolonged jaundice, and in males micropenis, microrchidism, and cryptorchidism in males [Scommegna et al., 2004; Mehta and Dattani, 2008]. A delay in diagnosis and treatment puts the neonate at high risk of death or irreversible CNS damage by hypoglycemia, acute adrenal insufficiency during stress, secondary hypothyroidism.

Diagnosis of CO-MPHD is confirmed by brain MRI, which usually detects anatomical alterations of the hypothalamic–pituitary area, such as anterior pituitary hypoplasia, ectopia, or absence of posterior pituitary, and thinning or interruption or absence of the pituitary stalk [Delman, 2009]. Complete absence of the anterior pituitary anterior pituitary aplasia (APA) has been reported only in very few cases [Scommegna et al., 2004; Arrigo et al., 2006]. Other midline defects, such as cleft lip and palate, choanal atresia or stenosis, solitary maxillary central incisor, agenesis of the septum pellucidum, or corpus callosum are also often associated [Mehta et al., 2009].

Anterior pituitary development depends on the sequential expression of transcription factors and signalling molecules [Mehta and Dattani, 2008]. Isolated or syndromic CO-MPHD is increasingly linked to mutations of genes encoding these transcription factors, such as PIT-1 (POU1F1), PROP1, HESX1, LHX3, and LHX4 [Kelberman and Dattani, 2007]. However, mutations in these genes appear to account for very few cases, suggesting that other genes or environmental factors are involved in this condition [Cohen and Radovick, 2002].

We report a molecular analysis and a clinical update of three previously described patients with a syndromic form of APA [Scommegna et al., 2004], and suggest that these cases may be due to a common, still unidentified, genetic defect.

CLINICAL REPORTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Scommegna et al. [2004] provided a clinical description of these three patients at a younger age. The corresponding clinical, hormonal, and neuroradiological data are summarized in Tables I–III and briefly recapitulated in the following reports.

Table I. Main Neonatal Clinical Findings
Clinical featuresPatient 1Patient 2Patient 3
Gestational age (week)393939
Birth weight (kg)3.93.13.5
Birth length (cm)514952
Head circumference (cm)373437
Respiratory distress+++
Hypoglycaemia+++
Hyponatremia++
Prolonged jaundice+++
Poor feeding+++
Seizures+++
Hypotonia+++
Table II. Hormonal Data at Diagnosis
Hormone (normal range)Patient 1Patient 2Patient 3
  • a

    Normal values vary, depending on age of patient.

GH during hypoglycemia (>20 ng/ml)2.80.20.15
Cortisol during hypoglycemia (>550 nmol/L)41.4115.5
TSH (0.5–5 mU/L)4.83.50.14
FT4 (9–26 pmol/L)4.16.62.4
LH (µIU/L)0.36Not doneNot done
FSH (µIU/L)1.26Not doneNot done
Testosterone (nmol/L)a<0.4 (1.9–13.3)a1.3 (0.52–1.56)a0.36 (2.8–11.4)a
Table III. MRI Findings
FeaturesPatient 1Patient 2Patient 3
Anterior pituitaryAplasiaAplasiaAplasia
Posterior pituitaryNot visibleNot visibleNot visible
Pituitary stalkAbsentCranial part thin, caudal part absentRudimentary
Sella turcicaHypoplasticHypoplasticHypoplastic
Optic nervesNormalNormalLeft optic nerve coloboma
BrainNormalNormalMild cortical atrophy

Patient 1

The patient was born at term by normal delivery from non-consanguineous healthy parents both from Central Italy after an uneventful pregnancy. Family history was unremarkable. A few hours after birth, he presented with respiratory distress, feeding difficulty, vomiting, poor reactivity, hypotonia, metabolic acidosis, prolonged non-cholestatic jaundice, and seizures, which occurred whenever glucose infusion was reduced. Micropenis and small testicles, palpable in the inguinal canal, were observed. Microcoria was also noted. Severe deficiency of ACTH, TSH, GH, LH, and FSH was demonstrated at age 18 days. The hormonal data collected during hypoglycemia (<2.2 mmol/L) in the neonatal period are summarized in Table II. Urine volume and concentration were normal.

Brain MRI, performed in the first month of life, showed a severely hypoplastic sella, with absence of both anterior and posterior pituitary and pituitary stalk. No other midline brain defects were detected (Table III).

Treatment with hydrocortisone, L-thyroxine, and rh-GH was started immediately after diagnosis, with rapid improvement of the clinical picture. Micropenis was treated with testosterone (25 mg i.m., three monthly administrations in the first year of life), with moderate increase of penis length and diameter. Bilateral orchidopexy was performed at age 3 years. Treatment with rh-FSH at age 8 years failed to significantly increase testicular volume and plasmatic levels of AMH and Inhibin B. Linear growth has been regular along the 90th centile. Congenital microcoria tended to improve over time. Diabetes insipidus appeared at 7 years. Treatment with desmopressin was started, with good control of symptoms.

At the more recent follow-up (age 11.7 years) height was 158.3 cm (+1.52 SDS), weight 57 kg (+2.4 SDS), and OFC 56.5 cm (+2 SDS). Genitalia were pre-pubertal, both testicles were in the scrotum, small (<1 ml), and soft, stretched penis length was 3.5 cm (<2 SDS). Distinct facial features included a low frontal hairline, sparse lateral eyebrows, epicanthal folds, long philtrum, broad nasal bridge, bulbous tip of nose, and long and narrow ears. Broad thumbs, broad halluces, pectus excavatum, widely spaced and inverted nipples, hyperlaxity of the joints, and hypotonia were also noted (Fig. 1a and Table IV).

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Figure 1. Distinctive facial appearance of our patients with frontal bossing, broad nasal bridge, and bulbous nasal tip.

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Table IV. Dysmorphic Features at Last Examination
FeaturesPatient 1Patient 2Patient 3
  1. +, present; −, absent.

Palpebral fissuresStraightStraightStraight
Hypertelorism+
EarsNormalLow-setNormal
Frontal bossing+++
Depressed nasal bridge+++
EyeMicrocoria hypertelorism hypermetropiaMicrocoria hypermetropia astigmatismLeft optic nerve coloboma hypermetropia astigmatism
ChoanesLeft stenosisBilateral stenosisNormal
PalateNormalFlat, narrowNormal
ToothAbsent lateral superior incisorsNormalHypoplasia of central lower incisors
Hands and feetNormalBilateral hand hexadactylyNormal
Microrchidism+++
CryptorchidismBilateralRight
Micropenis+++

The following neuropsychological features were present: delay in developmental milestones; improvement of speech and cognitive function during pre-school years, thanks to speech, and educational therapy, leading to low-average school performance; severe impairment of fine motor skills (drawing, writing), slowly improving during school years; clumsiness, not improving during school years.

Patient 2

The patient was born at term of an uneventful pregnancy by caesarean section from non-consanguineous parents, both originating from Southern Italy. The mother underwent removal of a pituitary adenoma a few years before his birth. Maternal (46 years) and paternal (48 years) ages were advanced. Two spontaneous miscarriages in the first trimester were reported. Soon after birth, the patient presented with inspiratory dyspnea, feeding difficulty, vomiting, hypotonia, prolonged non-cholestatic jaundice, and hypoglycemia, which occurred whenever glucose infusion was reduced. Penis and testicle were small; the right testicle was in the scrotum, while the left was palpable in the inguinal canal. Postaxial hexadactyly of both hands and microcoria were noted.

Severe deficiency of ACTH, TSH, GH, and testosterone was demonstrated in the first month (Table II). Urine volume and concentration were normal.

Brain MRI, performed in the first week of life, showed severely hypoplastic sella, with absence of both anterior and posterior pituitary. Pituitary stalk was thin in its cranial part, while the caudal portion was absent. No other midline brain defects were detected (Table III).

Treatment with hydrocortisone, L-thyroxine, and rh-GH was started immediately after diagnosis, with rapid improvement of the clinical picture. Micropenis was treated with testosterone (25 mg i.m., three monthly administrations in the semester of life), with moderate increase of penile length and diameter. Left orchidopexy was performed at age 3 years.

Treatment with rh-FSH at the age 5–8 years resulted in modest increase of the testicular volume and of the plasma levels of AMH and Inhibin B. Polydactyly was surgically repaired. Linear growth has been regular. Congenital microcoria improved over time. Inspiratory dyspnea, due to choanal stenosis, resolved spontaneously.

Follow-up at age 8.9 years showed a height of 135.2 cm (+0.6 SDS), weight 41 kg (+2.2 SDS), and OFC 50 cm (−1 SDS). Genitalia were pre-pubertal, both testicles were small (<1 ml), palpable in the scrotum, stretched penis length was 3 cm (<2 SDS). We noted low frontal hairline, frontal bossing, sparse lateral eyebrows, deep-set eyes, broad nasal bridge, bulbous tip of nose, hypoplastic midface, flat philtrum, cupid's bow configuration of the upper lip, posteriorly angulated ears, broad thumbs, remnants (scars) of postaxial hexadactyly on both hands, broad halluces, pectus excavatum, widely spaced and inverted nipples, and muscular hypotonia (Fig. 1b and Table IV).

The patient presented mild delay in developmental milestones; poor ability to maintain attention, and tendency to hyperactivity; improvement of speech function during pre-school years, thanks to speech, and educational therapy, leading to low-average school performance; severe impairment of fine motor skills (drawing, writing), slowly improving during school years.

Patient 3

The patient was born at term by caesarean after an uneventful pregnancy to non-consanguineous parents, both originating from Central Italy. The mother had multiple sclerosis and reported one spontaneous miscarriage in the first trimester.

Soon after birth, the patient presented with respiratory distress, feeding difficulty, vomiting, poor reactivity, hypotonia, metabolic acidosis, prolonged non-cholestatic jaundice, and severe hypoglycemia, which occurred whenever glucose infusion was reduced. Micropenis and micro-orchidism were present; both testicles were palpable in the scrotum. He also presented with generalized tonic–clonic seizures unrelated to hypoglycemia, as well as alteration of liver function tests, and anaphylactic shock during a blood transfusion.

Severe deficiency of ACTH, TSH, GH, and testosterone was demonstrated in the first week of life. The hormonal data in the neonatal period are summarized in Table II. Blood was drawn during hypoglycemia (<2.2 mmol/L). Urine volume and concentration were normal.

Brain MRI at age 40 days showed a severely hypoplastic sella, with absence of both anterior and posterior pituitary. Pituitary stalk was rudimentary. Left optic nerve coloboma was described; mild frontal and temporal cortical atrophy was also detected (Table III). Treatment with L-thyroxine was started at 10 days, with poor clinical response; hydrocortisone and rh-GH were added at age 40 days with significant improvement of symptoms. Micropenis was treated with testosterone (25 mg i.m., two monthly administrations in the first semester of life), with good increase of penile length and diameter. Treatment with rh-FSH at age 5 years resulted in modest increase of the testicular volume and the plasmatic levels of AMH and Inhibin B. Linear growth has been regular. A follow-up brain MRI at age 3 years confirmed pituitary aplasia, and showed multiple lesions in the white matter not prevoiusly noted, and attributed to post-natal hypoxic-ischemic damage.

The patient presented with mild delay in achievement of developmental milestones. His poor speech and cognitive function improved thanks to speech and educational therapy during pre-school years, leading to low-average school performance. At the age 4 years, on a formal evaluation of motor skills (ABC movements), he placed on the 3rd centile for age. His motor skills and hypotonia improved slowly during school years.

Physical examination, at age 8.5 years, showed a height of 134 cm (+0.87 SDS), weight 29.5 kg (+0.52 SDS), and OFC 52.0 cm (0 SDS). Genitalia were prepubertal, both testicles were small (<1 ml), stretched penile length was 3 cm (<2 SDS). Distinctive findings included frontal bossing, broad nasal bridge, bulbous tip of nose, short and flat philtrum, broad thumbs, and broad halluces, widely spaced nipples, hyperlaxity of joints, and muscular hypotonia (Fig. 1c and Table IV).

GENETIC ANALYSIS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

After parental informed consent, a peripheral blood sample was collected from each patient and their parents. An apparently normal 46,XY karyotype was detected in all patients by standard R(RBG) banding. Genomic DNA was extracted using the standard phenol–chloroform method. Sequence analysis of all coding exons and intron–exon boundaries of PROP1, POU1F, LHX3, and LHX4 by DHPLC, and of HESX1 by direct sequencing analysis, was normal.

Array-based comparative genomic hybridization (array-CGH) was performed using Agilent oligonucleotide-array kit 44B (Human Genome CGH Microarray kit 44B; Agilent Technologies, Santa Clara, CA), with an average resolution of about 75 kb, following the manufacturer's instructions. No genomic alterations were found in Patients 1 and 3. In Patient 2 an interstitial deletion spanning about 0.2 Mb was detected on 9p21.2 (first deleted: A_14_P136657-A_14_P109949; preserved: A_14_P137338-A_14_P103371; Fig. 2). An apparently identical deletion was carried by the clinically normal father suggesting that this may represent a benign structural variant. Nevertheless, to rule out that the patient's phenotype was due to compound heterozygosity of a recessive mutation not present in the father, we performed sequence analysis of genes included in the deleted region. According to the UCSC genome browser (UCSC Human genome browser, March 2006; http://genome.ucsc.edu/), the deletion interval includes TEK and MOBKL2B (or MOB3B), a ncRNA (NCRNA00032), and a cORF (C9ORF11). Direct sequencing of coding exons 1–23 of TEK (Gene Bank accession AB056507) and 2–4 of MOBKL2B and intronic flanking regions was performed on an ABI 3130 capillary sequencer (Applied Biosystems, Foster City, CA) after PCR amplification (detailed conditions and primer sequences are available on request). Sequence analysis did not show any mutation in the TEK gene and did not confirm the deletion of MOBKL2B detected by the array.

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Figure 2. Map of the deleted 200-kb––region within 9p21.2. Genes involved in the rearrangement are shown.

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DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

We describe three patients with a characteristic clinical and neuropsychological phenotype and congenital-onset deficiency of GH, TSH, ACTH, LH, and FSH (CO-MPHD) due to APA. In addition to well-known signs and symptoms of congenital hypopituitarism, clinical manifestations included distinctive facial appearance with frontal bossing, broad nasal bridge and bulbous tip of nose, broad thumbs, and widely spaced nipples. Ocular abnormalities (coloboma of left optic nerve in Patient 3 and microcoria in Patients 1 and 2) were also observed. Neurodevelopmental phenotype included hypotonia and global developmental delay in infancy; improvement of speech and gross motor function in the pre-school years; persistent impairment of fine motor function and clumsiness up to school-age. Some of the other cases of APA described in literature partly share these clinical features.

One patient described by Sobrier et al. [2005] harbored an optic nerve coloboma; both patients described by Al Gazali et al. [1999] presented microcoria, with one presenting also post-axial polydactyly. The clinical manifestations of these two patients led to suspect a variant form of oro-facial-digital syndrome.

Another patient [Sobrier et al., 2006] presented motor development delay and dysmorphic features (depressed nasal bridge, hypertelorism) similar to those observed in our patients. On the hand in other patients with APA, such as those published by Arrigo et al. [2006], no distinct facial or neuropsychological phenotype was described.

Causes of APA are still mostly unknown. We have therefore searched for environmental and genetic factors known to be linked to congenital hypopituitarism.

Perinatal insults, such as breech delivery and/or neonatal hypoxia, have been associated with pituitary defects through a traumatic or ischemic mechanism [Craft et al., 1980]. However, since our patients were born at term, after an uneventful pregnancy and delivery, and presented multiple congenital anomalies, it is highly unlikely that their phenotype is caused by perinatal insults.

Mutations in genes involved in the development of anterior pituitary, such as PROP1, POUF1, HESX1, LHX3, and LHX4 are known causes of CO-MPHD. Up to now, no mutation in PROP1, POUF1, LHX3, LHX4 has yet been found in patients with APA.

Sobrier et al. [2005, 2006] described three unrelated patients with APA and homozygous HESX1 mutations (two novel mutations and one Alu-element insertion). In our patients, however, no pathogenic mutation of HESX1 or of the other genes involved in the anterior pituitary development were found.

A whole genome screen using array-CGH identified an interstitial, paternally inherited deletion spanning about 0.2 Mb of 9p21.2 in Patient 2. According to the UCSC Genome Browser, this region contains two known genes MOBKL2B (or MOB3B) and TEK, a ncRNA (NCRNA00032), and a cORF (C9ORF11, Fig. 2). To clarify whether the phenotype in our patient might be due to a second mutation in the other allele, we carried out sequence analysis of both genes. MOBKL2B is homolog of the MOB1 that has potential tumor suppressor properties. It was recently found to be homozygously deleted in the mantle cell lymphoma (MCL) cell line MAVER-1, and monoallelic deletions are present in other MCL cell lines [Beà et al., 2009]. No germline mutation has been reported so far. Sequence analysis of MOBKL2B in Patient 2 and in his father identified two heterozygous polymorphisms, thus not confirming the deletion of this gene detected by the array.

TEK (GenBank NG_011828.1) encodes a receptor tyrosine kinase expressed almost exclusively in endothelial cells. Although only missense (activating) mutations of TEK have been described in an autosomal dominant condition with veno-muco-cutaneous malformation (VMCM), the possible effects of TEK haploinsufficiency are unknown [Wouters et al., 2010]. Two partial TEK deletions are reported in the database of genomic variants (http://projects.tcag.ca/variation) in two apparently normal individuals. However the significance of these deletions is unclear. They may represent rare, individual-specific, copy number variations (CNVs), false positives, or pathogenic deletions in undiagnosed patients.

Tek is a critical regulator of blood vessel development and Tek null mice are embryonically lethal due to vascular defects. Since adequate vascularization is required for pituitary development and cellular differentiation, we hypothesize that pituitary aplasia could be related to TEK inactivation. Thus, we investigated whether the TEK gene was mutated in our three patients. However, sequence analysis did not demonstrate mutations in any of them. However, its possible causative role cannot be completely ruled out, because we screened neither the control regions (promoter, 5′ and 3′ untranslated regions [UTRs]), nor the intervening sequences.

In conclusion, we have described three patients with a constellation of clinical and neurodevelopmental features possibly representing a novel syndrome, the genetic cause of which remains unidentified. Further studies with high-throughput sequencing technology should be conducted to identify this cause.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

We thank Prof. Serge Anselem and Dr. Marie-Laure Sobrier for performing genetic analysis of LHX4 and HES, 1 and Professor Pfäffle for performing genetic analysis of POUF1, PROP1 and LHX3. We thank Prof. Stefano Cianfarani for coordinating procedures for genetic analysis. We are grateful to the parents of the described children for allowing the publication.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. CLINICAL REPORTS
  5. GENETIC ANALYSIS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
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