Maternal age in patients with septo-optic dysplasia

Gastroschisis and septo-optic-pituitary dysplasia: Is there an association?

AIM

There are several case reports describing patients with both optic nerve hypoplasia/septo-optic-pituitary dysplasia (ONH/SOD) and gastroschisis (GS). Our aim was to investigate whether ONH/SOD is associated with GS.

METHODS

A retrospective population-based study was undertaken using the Population Research Data Repository at the Manitoba Center for Health Policy in Manitoba, Canada to investigate if any patient with ONH/SOD also had GS. In addition, Winnipeg's Surgical Database of Outcomes and Management (WiSDOM), a hospital-based paediatric surgical database, was searched to ascertain if any of the patients with GS also have ONH/SOD.

RESULTS

Cases were 124 patients with ONH/SOD diagnosed during 1990-2019. None had GS. The surgical database had 188 patients from Manitoba with GS during 1991-2019. None had ONH/SOD.

CONCLUSION

There does not appear to be an association between ONH/SOD and GS in our cohorts of patients with these two disorders.

Aberrant gene expression yet undiminished retinal ganglion cell genesis in iPSC-derived models of optic nerve hypoplasia

BACKGROUND

Optic nerve hypoplasia (ONH), the leading congenital cause of permanent blindness, is characterized by a retinal ganglion cell (RGC) deficit at birth. Multifactorial developmental events are hypothesized to underlie ONH and its frequently associated neurologic and endocrine abnormalities; however, environmental influences are unclear and genetic underpinnings are unexplored. This work investigates the genetic contribution to ONH RGC production and gene expression using patient induced pluripotent stem cell (iPSC)-derived retinal organoids (ROs).

MATERIALS AND METHODS

iPSCs produced from ONH patients and controls were differentiated to ROs. RGC genesis was assessed using immunofluorescence and flow cytometry. Flow-sorted BRN3+ cells were collected for RNA extraction for RNA-Sequencing. Differential gene expression was assessed using DESeq2 and edgeR. PANTHER was employed to identify statistically over-represented ontologies among the differentially expressed genes (DEGs). DEGs of high interest to ONH were distinguished by assessing function, mutational constraint, and prior identification in ONH, autism and neurodevelopmental disorder (NDD) studies.

RESULTS

RGC genesis and survival were similar in ONH and control ROs. Differential expression of 70 genes was identified in both DESeq2 and edgeR analyses, representing a ~ 4-fold higher percentage of DEGs than in randomized study participants. DEGs showed trends towards over-representation of validated NDD genes and ONH exome variant genes. Among the DEGs, RAPGEF4 and DMD had the greatest number of disease-relevant features.

CONCLUSIONS

ONH genetic background was not associated with impaired RGC genesis but was associated with DEGs exhibiting disease contribution potential. This constitutes some of the first evidence of a genetic contribution to ONH.

Risk factors in children with optic nerve hypoplasia and septo-optic dysplasia

AIM

To identify the risk factors for optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD).

METHOD

A retrospective, population-based study with case-control design was undertaken using the Population Research Data Repository at the Manitoba Center for Health Policy in Manitoba, Canada. Cases were 111 patients (63 males, 48 females; age range 1-35 years [mean 11 years 6 months, SD 7 years 2 months]) with ONH and SOD diagnosed from 1990 to 2019, matched to 555 unrelated population-based controls (315 males, 240 females; age range 1-35 years [mean 11 years 6 months, SD 7 years 2 months]) on year of birth, sex, and area of residence. Additionally, 75 cases (46 males, 29 females; age range 2-35 years [mean 12 years 6 months, SD 7 years 2 months]) with ONH and SOD were matched one-on-one with sibling controls (40 males, 35 females; age range 0-33 years [mean 11 years 7 months, SD 7 years 10 months], the rest did not have siblings). Several antenatal maternal risk factors associated with ONH and SOD were tested for their association with case and control group membership using adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from a multivariate conditional logistic regression model. The outcome was the risk of developing ONH and SOD.

RESULTS

Maternal age at conception (OR = 0.91, 95% CI = 0.86-0.96), primigravida (OR = 3.39, 95% CI = 1.92-6.01), and smoking (OR = 2.86, 95% CI = 1.61-5.05) were independently associated with ONH and SOD in the cohort matched to unrelated controls (p < 0.001). In the sibling cohort, smoking was an important risk factor (OR = 3.65, 95% CI = 1.2-11.1, p = 0.02).

INTERPRETATION

Unmodifiable and modifiable antenatal maternal risk factors are associated with ONH and SOD. Our investigation suggests that several risk factors reported in previous studies may have been due to confounding bias and that maternal smoking during pregnancy is the main modifiable risk factor associated with ONH and SOD.

WHAT THIS PAPER ADDS

Historically, many antenatal risk factors have been associated with optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD). Population-based data with matched controls for potential confounding bias are lacking. Young maternal age at conception, primigravida, and smoking during pregnancy are the main risk factors for ONH and SOD using a population-based, case-control design.

Visual Acuity Outcomes in Children With Optic Nerve Hypoplasia and Septo-Optic-Pituitary Dysplasia

BACKGROUND

To investigate best-corrected visual acuity (BCVA) outcomes in patients with optic nerve hypoplasia (ONH)/septo-optic-pituitary dysplasia (SOD). Our primary hypothesis was that BCVA in patients with ONH/SOD does not change significantly over time.

METHODS

A chart review was undertaken in patients with a confirmed diagnosis of ONH/SOD. Demographic and clinical ophthalmologic data were extracted. Quantitative BCVA data were investigated across clinic visits after converting acuities to the logarithm of the minimum angle of resolution (logMAR).

RESULTS

There were 102 patients (56 males). Median age at the end of the study was 12.7 years. Median duration of follow-up was 4.5 years. BCVA significantly worsened slightly in the most affected eyes (0.056 average increase in logMAR/year, 95% confidence interval [CI]: 0.037 to 0.075) and significantly improved mildly in the lesser or equally affected eyes (0.014 average decrease in logMAR/year, 95% CI: 0.009 to 0.019) (P < 0.0001).

CONCLUSIONS

Although the overall BCVA data showed a statistically significant change with time, the actual changes were small and are of doubtful meaningful clinical significance (less than one line change on a Snellen chart). Our data suggest that ONH/SOD are nonprogressive neurodevelopmental disorders. The mild worsening of BCVA in the most affected eyes may be caused by amblyopia, whereas the small improvement in the lesser or equally affected eyes may be caused by developmental maturation. In addition, the changes in BCVA may also be due to increasing reliability of visual assessments with increasing age.

Patients with septo-optic dysplasia: General ophthalmologic assessment and retinal imaging

BACKGROUND

To evaluate the functional development and, retinal and optic disc morphology using OCT in patients with septo-optic dysplasia (SOD).

METHODS

This retrospective case series included patients diagnosed with SOD between 2007 and 2020. Ophthalmologic assessment included visual acuity (VA) and funduscopy at the initial and last presentation. Retinal imaging included OCT of the macula analyzing the retinal morphology, central retinal thickness volume (CRT) and ganglion cell layer (GCL). Also, scans of the optic nerve head were taken to evaluate the retinal nerve fiber layer (RNFL) and global value.

RESULTS

38 eyes of 19 children with a mean age 6.3 ± 5.3 years were included. 31.6% showed all 3 characteristics of SOD, whereof ONH, midline defects and endocrine dysfunctions were found in 94.7%, 89.5% and 47.4% respectively. The mean VA was 0.70 ± 0.66logMar in the right eye (RE) and 0.40 ± 0.55logMar in the left eye (LE) at the initial presentation. No change of vision (RE: 0.69 ± 0.71logMar; LE: 0.31 ± 0.57logMar) was found after a follow-up period of 6.3 ± 4.5years. Funduscopy showed an ONH in 79% (n = 30/38), tortuous retinal vessels in 36.8% (n = 14/38) and a double-ring sign in 15.8% (n = 6/38). Retinal imaging showed variable morphology. 6 eyes of 4 patients showed temporal retinal thinning with corresponding GCL attenuation. The optic nerve head appearance varied between no changes, sectoral and hemispherical reduction.

CONCLUSIONS

Patients suffering from SOD show diverse expression of retinal changes such as retinal, GCL and RNFL thinning in OCT. Furthermore, visual function remained stable during follow-up examinations, indicating no further alteration due to underlying pathology.

Association of prepregnancy body mass index and gestational weight gain on severity of optic nerve hypoplasia

BACKGROUND

Optic nerve hypoplasia (ONH) is a birth defect of unknown etiology and a leading cause of visual impairment in developed countries. Recent studies suggest that factors of deprivation and exposures of poor nutritional status, such as lower gestational weight gain (GWG), may be associated with increased risk of ONH. The present study describes the prenatal features of mothers of ONH cases, including prepregnancy BMI and GWG, and the associations with clinical features of disease severity.

METHODS

Retrospective study of prenatal records for cases of ONH enrolled in a research registry. Prepregnancy BMI and GWG were compared to maternal characteristics and clinical findings of ONH severity including bilaterality, hypopituitarism, and neuroradiographic abnormalities.

RESULTS

Compared to population-based normative data of births in the United States, mothers of ONH cases (n = 55) were younger (23.3 vs. 25.8 years; p = 0.03), with higher incidence of inadequate GWG (34.0% vs. 20.4%; p = 0.03) predominantly in the first and second trimesters. The presence of major brain malformations was associated with younger maternal age (21.6 [IQR 19.4, 24.7] vs. 24.9 years [IQR 22.1, 28.5] [p = 0.02]), primiparity (44.1% vs. 13.3%; p = 0.05) and decreased prepregnancy BMI (20.9 kg/m2 [19, 22.5] vs. 25.5 kg/m2 [21.3, 28.2]; p < 0.01).

CONCLUSION

Decreased prepregnancy BMI and inadequate GWG correlated with clinical features of ONH severity, specifically bilateral disease and presence of major brain malformations.

Breastfeeding Success and Newborn Health before and during the COVID-19 Pandemic:A Single-Centre Comparative Study

INTRODUCTION

Due to the SARS-CoV-2 pandemic, adjustments in patient and visitor traffic were made in hospitals to limit viral exposure. The primary objective of our study was to compare the breastfeeding success of healthy newborns in a maternity ward during the 2020 lockdown period compared with the same period in the previous year.

MATERIAL AND METHODS

Single-center comparative study based on prospectively collected data. All neonates born alive, from a single pregnancy, and with a gestational age greater than 36 weeks were considered for this study.

RESULTS

309 infants born in 2020 and 330 born in 2019 were included. Among women who desired to exclusively breastfeed, the rate of exclusive breastfeeding at discharge from the maternity ward was higher in 2020 than in 2019 (85 vs. 79%; p = 0.078). After logistic regression analysis adjusted for potential confounders (i.e., maternal BMI, parity, mode of delivery, gestational age, and size at birth), study period remained significantly and independently associated with exclusive breastfeeding at discharge (OR [95% CI] = 1.645 [1.005; 2.694]; p = 0.046). Newborns born in 2020 were less likely to have weight loss ≥10% than those born in 2019 (OR [95% CI] = 2.596 [1.148; 5.872]; p = 0.017) but had similar need for phototherapy (p = 0.41).

CONCLUSION

The success of exclusive breastfeeding during the 2020 lockdown period was increased compared with the same period in 2019.

Selected Ophthalmological Features in Children with Septo-Optic Dysplasia and Optic Nerve Hypoplasia

Septo-optic dysplasia (SOD) and optic nerve hypoplasia (ONH) cause congenital visual impairment. Their aetiology is mostly unknown. Our aim was to investigate the prevalence of selected ophthalmological features in patients with these disorders. A chart review was performed on patients with SOD/ONH. Ophthalmological data were extracted. There were 102 patients (56 males). The median age at the end of the study was 12.7 years. Best-corrected visual acuity ranged from normal to no light perception. Bilateral ONH was more common than unilateral ONH. Strabismus (85%) and to a lesser extent nystagmus (52%) were both very common in our cohort. Patients with esotropia had worse visual acuity than those who had exotropia. The presence of nystagmus was more likely in cases with bilateral ONH. Therefore, patients with SOD/ONH may have normal visual acuity. Many have strabismus, which may cause amblyopia thereby further decreasing visual acuity. Nystagmus occurs commonly and its presence typically indicates bilateral ONH.

Review of the MRI brain findings of septo-optic dysplasia

AIM

To report the magnetic resonance imaging (MRI) findings from a retrospective case analysis of children with septo-optic dysplasia (SOD), a rare congenital disorder characterised by any combination of midline brain defects, optic nerve hypoplasia (ONH), and hypothalamic-pituitary dysfunction.

MATERIALS AND METHODS

SOD was defined radiologically as complete or partial septum pellucidum (SP) absence with hypoplasia of at least one of the optic nerves and/or chiasm. Local MRI databases were searched for SOD cases in children over an 18-year period, and studies reviewed by two consultant paediatric neuroradiologists. The extent of structural SP, optic nerve, chiasm, and hypothalamic-pituitary involvement was recorded, along with coexisting brain abnormalities.

RESULTS

Forty-eight cases of SOD were found; 44/48 (92%) demonstrated complete SP absence whereas 4/48 (8%) had partial absence. Eight of 48 cases (17%) exhibited unilateral ONH. Fifty-one percent of cases, where the pituitary was identified on MRI, demonstrated a structural pituitary abnormality, which included an ectopic posterior bright spot in 6%. The olfactory nerves were hypoplastic in 5/48 cases (10%). Twenty-seven of the 48 cases (56%) had another brain abnormality, resulting from some form of cortical formation abnormality/schizencephaly in 21/48 (44%).

CONCLUSION

A high rate of associated brain abnormalities was found in the present cohort, including structural pituitary abnormalities in 51% and cortical formation abnormalities/schizencephaly in 44%. This suggests there is not a single cause for SOD, rather SOD is the phenotypic end point from multiple aetiological events. Individual children with SOD may have coexisting intracranial abnormalities, and, hence, high-quality MRI is required in all.

Epidemiology of septo-optic dysplasia with focus on prevalence and maternal age - A EUROCAT study

Septo-optic nerve dysplasia is a rare congenital anomaly with optic nerve hypoplasia, pituitary hormone deficiencies and midline developmental defects of the brain. The clinical findings are visual impairment, hypopituitarism and developmental delays. The aim of this study was to report prevalence, associated anomalies, maternal age and other epidemiological factors from a large European population based network of congenital anomaly registries (EUROCAT). Data from 29 full member registries for the years 2005-2014 were included, covering 6.4 million births. There were 99 cases with a diagnosis of septo-optic dysplasia. The prevalence of septo-optic dysplasia in Europe was calculated to lie between 1.9 and 2.5 per 100,000 births after adjusting for potential under-reporting in some registries. The prevalence was highest in babies of mothers aged 20-24 years of age and was significantly higher in UK registries compared with other EUROCAT registries (P = 0.021 in the multilevel model) and the additional risk for younger mothers was significantly greater in the UK compared to the rest of Europe (P = 0.027). The majority of septo-optic dysplasia cases were classified as an isolated cerebral anomaly (N = 76, 77%). Forty percent of diagnoses occurred in fetuses with a prenatal diagnosis. The anomaly may not be visible at birth, which is reflected in that 57% of the postnatal diagnoses occurred over 1 month after birth. This is the first population based study to describe the prevalence of septo-optic dysplasia in Europe. Septo-optic dysplasia shares epidemiological patterns with gastroschisis and this strengthens the hypothesis of vascular disruption being an aetiological factor for septo-optic dysplasia.

Congenital anomalies of the optic disc: insights from optical coherence tomography imaging

PURPOSE OF REVIEW

Congenital anomalies of the optic nerve are rare but significant causes of visual dysfunction in children and adults. Accurate diagnosis is dependent on a thorough funduscopic examination, but can be enhanced by imaging information garnered from optical coherence tomography (OCT). We review common congenital optic nerve anomalies, including optic disc pit, optic nerve coloboma, morning glory disc anomaly, and hypoplasia of the optic nerve, review their systemic associations, and discuss insights from OCT imaging.

RECENT FINDINGS

Optic disc pits are a result of a defect in the lamina cribrosa and abnormal vitreomacular adhesions have been shown to cause maculopathy. In patients with optic nerve colobomas, OCT can be instrumental in diagnosing choroidal neovascularization, a rare but visually devastating complication. The pathogenesis of morning glory disc anomaly has been more clearly elucidated by OCT as occurring from a secondary postnatal mesenchymal abnormality rather than only the initial neuroectodermal dysgenesis of the terminal optic stalk in isolation. OCT studies of optic nerve hypoplasia have demonstrated significant thinning of the inner and outer retinal layers of the perifoveal region and thicker layers in the fovea itself, resulting in a foveal hypoplasia-like pathology, that is, significantly correlated to poorer visual outcomes.

SUMMARY

OCT provides detailed in-vivo analysis of these anatomic anomalies and their resulting pathologies, shedding new insights on the pathogenesis, diagnosis, and potential visual outcomes of these conditions in children. Further study employing OCT to elucidate structure-function relationships of congenital optic nerve anomalies will help expand the role of OCT in clinical practice related to diagnosis, prognosis, and management of these entities.

Clinical and Radiologic Spectrum of Septo-optic Dysplasia: Review of 17 Cases

We retrospectively reviewed the clinical and radiologic characteristics of 17 individuals with septo-optic dysplasia (SOD) and attempted to identify correlations between imaging findings, clinical features, and neurodevelopmental outcome. Surprisingly, only 1 (6%) individual was classified as classic SOD (with septum pellucidum/corpus callosum dysgenesis), 3 (18%) as SOD-like (with normal septum pellucidum/corpus callosum) and the majority, 13 (76%), as SOD-plus (with cortical brain malformation). Cortical abnormalities included schizencephaly, polymicrogyria, and gray matter heterotopias. All individuals had optic nerve hypoplasia, 11 (65%) had endocrinologic deficits, and 13 (76%) had abnormal cerebral midlines. Seven individuals (41%) had all 3 features. Neurodevelopmental outcome was abnormal in 13 (78%), ranging from mild to severe developmental delay. Individuals with SOD-plus did not have more severe neurologic deficits than individuals with classic or SOD-like subgroups. Thus, SOD is clinically and radiologically heterogeneous, and cortical abnormalities are very common. Neurodevelopmental deficits are very prevalent, and of wide-ranging severity.

Classical and non-classical causes of GH deficiency in the paediatric age

Growth hormone deficiency (GHD) may result from a failure of hypothalamic GHRH production or release, from congenital disorders of pituitary development, or from central nervous system insults including tumors, surgery, trauma, radiation or infiltration from inflammatory diseases. Idiopathic, isolated GHD is the most common sporadic form of hypopituitarism. GHD may also occur in combination with other pituitary hormone deficiencies, and is often referred to as hypopituitarism, combined pituitary hormone deficiency (CPHD), multiple pituitary hormone deficiency (MPHD) or panhypopituitarism. Children without any identifiable cause of their GHD are commonly labeled as having idiopathic hypopituitarism. MRI imaging is the technique of choice in the diagnosis of children with hypopituitarism. Marked differences in MRI pituitary gland morphology suggest different etiologies of GHD and different prognoses. Pituitary stalk agenesis and ectopic posterior pituitary (EPP) are specific markers of permanent GHD, and patients with these MRI findings show a different clinical and endocrine outcome compared to those with normal pituitary anatomy or hypoplastic pituitary alone. Furthermore, the classic triad of ectopic posterior pituitary gland, pituitary stalk hypoplasia/agenesis, and anterior pituitary gland hypoplasia is generally associated with permanent GHD. T2 DRIVE images aid in the identification of pituitary stalk without the use of contrast medium administration. Future developments in imaging techniques will undoubtedly reveal additional insights. Mutations in a number of genes encoding transcription factors - such as HESX1, SOX2, SOX3, LHX3, LHX4, PROP1, POU1F1, PITX, GLI3, GLI2, OTX2, ARNT2, IGSF1, FGF8, FGFR1, PROKR2, PROK2, CHD7, WDR11, NFKB2, PAX6, TCF7L1, IFT72, GPR161 and CDON - have been associated with pituitary dysfunction and abnormal pituitary gland development; the correlation of genetic mutations to endocrine and MRI phenotypes has improved our knowledge of pituitary development and management of patients with hypopituitarism, both in terms of possible genetic counseling, and of early diagnosis of evolving anterior pituitary hormone deficiencies.

Prenatal ethanol exposure in mice phenocopies Cdon mutation by impeding Shh function in the etiology of optic nerve hypoplasia

Septo-optic dysplasia (SOD) is a congenital disorder characterized by optic nerve, pituitary and midline brain malformations. The clinical presentation of SOD is highly variable with a poorly understood etiology. The majority of SOD cases are sporadic, but in rare instances inherited mutations have been identified in a small number of transcription factors, some of which regulate the expression of Sonic hedgehog (Shh) during mouse forebrain development. SOD is also associated with young maternal age, suggesting that environmental factors, including alcohol consumption at early stages of pregnancy, might increase the risk of developing this condition. Here, we address the hypothesis that SOD is a multifactorial disorder stemming from interactions between mutations in Shh pathway genes and prenatal ethanol exposure. Mouse embryos with mutations in the Shh co-receptor, Cdon, were treated in utero with ethanol or saline at embryonic day 8 (E8.0) and evaluated for optic nerve hypoplasia (ONH), a prominent feature of SOD. We show that both Cdon^-/- mutation and prenatal ethanol exposure independently cause ONH through a similar pathogenic mechanism that involves selective inhibition of Shh signaling in retinal progenitor cells, resulting in their premature cell-cycle arrest, precocious differentiation and failure to properly extend axons to the optic nerve. The ONH phenotype was not exacerbated in Cdon^-/- embryos treated with ethanol, suggesting that an intact Shh signaling pathway is required for ethanol to exert its teratogenic effects. These results support a model whereby mutations in Cdon and prenatal ethanol exposure increase SOD risk through spatiotemporal perturbations in Shh signaling activity.

Spectrum of clinical presentations and endocrinological findings of patients with septo-optic dysplasia: a retrospective study

BACKGROUND

Septo-optic dysplasia (SOD) is a rare condition with variable clinical pictures and spectrum of findings.

OBJECTIVE

To analyze the spectrum of findings, frequency and age of onset of hypothalamic-pituitary dysfunctions in children with SOD.

METHOD

A retrospective electronic medical record (EMR) chart review was done for patients with SOD seen in a tertiary care center's pediatric endocrinology clinic between January 1, 2012, and March 31, 2014. The diagnostic criteria for SOD included presence of ≥ 2 of the following: (i) optic nerve hypoplasia, (ii) agenesis/hypoplasia of septum pellucidum and/or corpus callosum and (iii) hypothalamic-pituitary dysfunction.

RESULTS

Eighty patients fitting the diagnostic criteria of SOD were included in this study. The majority of patients (96%) had optic nerve hypoplasia on magnetic resonance imaging and were diagnosed due to visual issues including nystagmus (36%) or strabismus (13.8%). Hypothalamic-pituitary dysfunction was most common (51%) when optic nerve hypoplasia was present with (36%) or without (15%) dysgenesis of septum pellucidum and/or corpus callosum compared to dysgenesis of septum pellucidum and/or corpus callosum alone (4%). Hypothalamic-pituitary dysfunction was noted in 55% of patients, and most (86%) were diagnosed ≤ 2 years of age. Central hypothyroidism and growth hormone deficiency were most common followed by secondary/tertiary adrenal insufficiency and diabetes insipidus.

CONCLUSIONS

The risk of hypothalamic-pituitary dysfunction in SOD is highest ≤ 2 years of age and when both optic nerve hypoplasia and dysgenesis of septum pellucidum/corpus callosum are present, suggesting a need for more frequent follow-up and screening tests for hypothalamic-pituitary dysfunction in these patients.

Prenatal determinants of optic nerve hypoplasia: review of suggested correlates and future focus

Optic nerve hypoplasia (ONH), a congenital malformation characterized by an underdeveloped optic nerve, is a seemingly epidemic cause of childhood blindness and visual impairment with associated lifelong morbidity. Although the prenatal determinants of ONH are unknown, early case reports have led to a longstanding speculation that risky health behaviors (e.g., prenatal use of recreational drugs, alcohol) are a likely culprit. There has yet to be a systematic review of the epidemiology of ONH to assess the common prenatal features that may help focus research efforts in the identification of likely prenatal correlates. A review of the past 50 years of epidemiologic research was conducted to examine the prenatal features linked with ONH and provide direction for future research. There are select prominent prenatal features associated with ONH: young maternal age and primiparity. Commonly implicated prenatal exposures (recreational or pharmaceutical drugs, viral infection, etc.) were rare or uncommon in large cohort studies of ONH and therefore unlikely to be major contributors to ONH. Familial cases and gene mutations are rare. The preponderance of young mothers and primiparity among cases of ONH is striking, although the significance is unclear. Recent research suggests a potential role for prenatal nutrition, weight gain, and factors of deprivation. With the rapidly increasing prevalence of ONH, future research should focus on investigating the relevance of young maternal age and primiparity and exploring the recently suggested etiologic correlates in epidemic clusters of ONH.

Optic nerve hypoplasia syndrome: a review of the epidemiology and clinical associations

OPINION STATEMENT

BACKGROUND

Optic nerve hypoplasia (ONH) has developed into a leading cause of congenital blindness. The frequently associated features of hypopituitarism and absent septum pellucidum were felt to have embryonic linkage as "septo-optic dysplasia" or "de Morsier's syndrome." More recent studies have suggested these associations are independent of one another. This review provides an assessment of the historical and recent evidence linking neuroradiologic, endocrinologic and developmental morbidity in patients with ONH. The prenatal risk factors, heritability, and genetic mutations associated with ONH are described.

RESULTS

Recognition of the critical association of ONH with hypopituitarism should be attributed to William Hoyt, not Georges de Morsier. De Morsier never described a case of ONH or recognized its association with hypopituitarism or missing septum pellucidum. Hypopituitarism is caused by hypothalamic dysfunction. This, and other more recently identified associations with ONH, such as developmental delay and autism, are independent of septum pellucidum development. Other common neuroradiographic associations such as corpus callosum hypoplasia, gyrus dysplasia, and cortical heterotopia may have prognostic significance. The predominant prenatal risk factors for ONH are primiparity and young maternal age. Presumed risk factors such as prenatal exposure to drugs and alcohol are not supported by scrutiny of the literature. Heritability and identified gene mutations in cases of ONH are rare.

CONCLUSION

Children with ONH require monitoring for many systemic, developmental, and even life-threatening problems independent of the severity of ONH and presence of brain malformations including abnormalities of the septum pellucidum. "Septo-optic dysplasia" and "de Morsier's syndrome" are historically inaccurate and clinically misleading terms.

Reappraisal of the optic nerve hypoplasia syndrome

BACKGROUND

Optic nerve hypoplasia (ONH) has been described as an increasingly prevalent cause of congenital blindness. Its association with hypopituitarism and absent septum pellucidum has been recognized for more than 40 years as "septo-optic dysplasia" or "de Morsier syndrome." More recent studies have suggested that these associations are independent of one another. This review was designed to assess the historical and recent evidence for associations of neuroradiologic, endocrinologic, and developmental problems in patients with ONH.

EVIDENCE ACQUISITION

Historical and contemporary literature review.

RESULTS

The medical literature does not support the notion that Georges de Morsier ever described a case of ONH or recognized its association with hypopituitarism or missing septum pellucidum. Recognition of the critical association of ONH with hypopituitarism should be attributed to William Hoyt. Hypopituitarism and other more recently identified associations with ONH, such as developmental delay, hypothalamic dysfunction, and autism, are independent of septum pellucidum development. Other common neuroradiographic associations, such as corpus callosum hypoplasia, gyrus dysplasia, and cortical heterotopia, may have prognostic significance.

CONCLUSIONS

Children with ONH need to be monitored for many systemic, developmental, and even life-threatening problems independent of the status of the septum pellucidum. "Septo-optic dysplasia" and "de Morsier syndrome" are historically inaccurate and clinically misleading terms that should be abandoned.

The role of homeodomain transcription factors in heritable pituitary disease

The anterior pituitary gland secretes hormones that regulate developmental and physiological processes, including growth, the stress response, metabolic status, reproduction and lactation. During embryogenesis, cellular determination and differentiation events establish specialized hormone-secreting cell types within the anterior pituitary gland. These developmental decisions are mediated in part by the actions of a cascade of transcription factors, many of which belong to the homeodomain class of DNA-binding proteins. The discovery of some of these regulatory proteins has facilitated genetic analyses of patients with hormone deficiencies. The findings of these studies reveal that congenital defects-ranging from isolated hormone deficiencies to combined pituitary hormone deficiency syndromes-are sometimes associated with mutations in the genes encoding pituitary-acting developmental transcription factors. The phenotypes of affected individuals and animal models have together provided useful insights into the biology of these transcription factors and have suggested new hypotheses for testing in the basic science laboratory. Here, we summarize the gene regulatory pathways that control anterior pituitary development, with emphasis on the role of the homeodomain transcription factors in normal pituitary organogenesis and heritable pituitary disease.

Genetic regulation of pituitary gland development in human and mouse

Normal hypothalamopituitary development is closely related to that of the forebrain and is dependent upon a complex genetic cascade of transcription factors and signaling molecules that may be either intrinsic or extrinsic to the developing Rathke's pouch. These factors dictate organ commitment, cell differentiation, and cell proliferation within the anterior pituitary. Abnormalities in these processes are associated with congenital hypopituitarism, a spectrum of disorders that includes syndromic disorders such as septo-optic dysplasia, combined pituitary hormone deficiencies, and isolated hormone deficiencies, of which the commonest is GH deficiency. The highly variable clinical phenotypes can now in part be explained due to research performed over the last 20 yr, based mainly on naturally occurring and transgenic animal models. Mutations in genes encoding both signaling molecules and transcription factors have been implicated in the etiology of hypopituitarism, with or without other syndromic features, in mice and humans. To date, mutations in known genes account for a small proportion of cases of hypopituitarism in humans. However, these mutations have led to a greater understanding of the genetic interactions that lead to normal pituitary development. This review attempts to describe the complexity of pituitary development in the rodent, with particular emphasis on those factors that, when mutated, are associated with hypopituitarism in humans.

The subclassification of schizencephaly and its clinical characterization

We subclassified schizencephaly based on the association with optic nerve hypoplasia (ONH) and the absence of the septum pellucidum (ASP), and then characterized their clinical presentation and prognosis. The subjects of our study consisted of 10 cases with a mean age at the final evaluation of 10 years 3 months (range, 7 months to 25 years). The subclassification of schizencephaly consisted of the septo-optic dysplasia (SOD) group (n=3), with ONH and ASP; the optic hypoplasia (OHP) group (n=2), with ONH and without ASP, and; the classical group (n=5), without ONH. The subjects with an open-lip cleft in the SOD and the classical group showed hydrocephalus, but those in the OHP group did not. The SOD and the OHP group displayed severe psychomotor retardation regardless of the cleft morphology, but in the classical group, the subjects with an open-lip cleft or with diffuse cortical dysplasia were severely retarded. The SOD and the OHP group displayed intractable epilepsy. In contrast, all subjects in the classical group showed good control of epilepsy. The results of our investigation show that the subclassification of schizencephaly based on the association with ONH and ASP is useful. The SOD group means early fetal brain injury which results in extended cortical dysplasia while the OHP group means severe destructive brain injury which results in cerebro-cerebellar disruption.

Refining clinical phenotypes in septo-optic dysplasia based on MRI findings

Septo-optic dysplasia (SOD) is a heterogeneous brain midline anomaly associated with ophthalmological, endocrinological, and/or neurodevelopmental symptoms. The clinical phenotype correlates with abnormal brain magnetic resonance imaging (MRI) findings. However, variations of the septum pellucidum (SP) appearance and their clinical impact have not been studied in depth. Sixty-eight patients with optic nerve hypoplasia (ONH) were investigated for the presence of associated SP anomalies and correlations between clinical findings and their MRI abnormalities established. Thirty patients had either complete (n = 22) or partial (n = 8) absence of the SP. Pituitary hormone deficiencies were present in 64% or 25% of the cases, respectively. Neurological symptoms did not occur in patients with SP remnants or unilateral ONH. Hippocampus abnormalities (43%) that have not been described before in SOD and falx abnormalities (17%) correlated significantly with neurological symptoms and developmental delay (p < 0.05 and p < 0.01, respectively). Maternal age at birth was low (21.2 years) and drug abuse during pregnancy was reported in 27% of the patients. Twelve patients with pituitary anomaly and ONH but normal SP showed similar clinical and MRI features, and were classified as SOD-like. The remaining 26 patients were not assigned to SOD. We conclude that unilateral ONH and SP remnants are associated with a milder SOD phenotype. Hippocampus abnormalities and falx abnormalities seem to constitute important features of severe clinical disease, irrespective of SP appearance. Our anamnestic data support the hypothesis of vascular disruption during embryogenesis.

Associations with multiple pituitary hormone deficiency in patients with an ectopic posterior pituitary gland

INTRODUCTION

The presence of an ectopic posterior pituitary gland (EPP) on magnetic resonance imaging (MRI) is associated with hypopituitarism with one or more hormone deficiencies. We aimed to identify risk factors for having multiple pituitary hormone deficiency (MPHD) compared to isolated growth hormone deficiency (IGHD) in patients with an EPP.

METHODS

In 67 patients (45 male) with an EPP on MRI, the site (hypothalamic vs. stalk) and surface area (SA) [ x (maximum diameter/2) x (maximum height/2), mm(2)] of the EPP were recorded and compared in patients with IGHD and MPHD in relation to clinical characteristics.

RESULTS

In MPHD (n = 32) compared to IGHD (n = 35) patients: age of presentation was younger (1.4 [0.1-10.7]vs. 4.0 [0.1-11.3] years, P = 0.005), major incidents during pregnancy were increased (47%vs. 20%, P = 0.02) as were admissions to a neonatal intensive care unit (NICU) (60%vs. 26%, P = 0.04), whilst EPP SA was lower (12.3 [2.4-34.6]vs. 25.7 [6.9-48.2] mm(2), P < 0.001). In patients with a hypothalamic (n = 56) compared to a stalk sited EPP (n = 11): prevalence of MPHD was greater (55%vs. 9%,P = 0.05) and EPP surface area was smaller (17.3 [2.4-48.2]vs. 25.3 [11.8-38.5] mm(2), P < 0.001). In regression analysis, after adjusting for age, presence of MPHD was associated with: major incidents during pregnancy (RR 6.8 [95%CI 1.2-37.7]), hypothalamic EPP site (RR 10.9 [1.0-123.9]) and small EPP SA (RR 2.5 [1.0-5.0] for tertiles of SA).

CONCLUSION

In patients with an EPP, adverse antenatal events, size (small) and position (hypothalamic) of the posterior pituitary gland on MRI were associated with MPHD. These findings suggest that adverse factors during pregnancy may be important for the development of an EPP.

Developmental disorders of the hypothalamus and pituitary gland associated with congenital hypopituitarism

The pituitary gland is a complex organ secreting six hormones from five different cell types. It is the end product of a carefully orchestrated pattern of expression of signalling molecules and transcription factors. Naturally occurring and transgenic murine models have demonstrated a role for many of these molecules in the aetiology of congenital hypopituitarism. These include the transcription factors HESX1, PROP1, POU1F1, LHX3, LHX4, PITX1, PITX2, SOX2 and SOX3. The expression pattern of these transcription factors dictates the phenotype that results when the gene encoding the relevant transcription factor is mutated. The highly variable phenotype may consist of isolated hypopituitarism or more complex disorders such as septo-optic dysplasia and holoprosencephaly. However, the overall incidence of mutations in known transcription factors in patients with hypopituitarism is low, indicating that many genes remain to be identified; characterization of these will further elucidate the pathogenesis of this complex condition and also shed light on normal pituitary development and function.

HESX1 mutations are an uncommon cause of septooptic dysplasia and hypopituitarism

CONTEXT

Mutations in the transcription factor HESX1 have previously been described in association with septooptic dysplasia (SOD) as well as isolated defects of the hypothalamic-pituitary axis.

OBJECTIVE

Given that previous screening was carried out by SSCP detection alone and limited to coding regions, we performed an in-depth genetic analysis of HESX1 to establish the true contribution of HESX1 genetic defects to the etiology of hypopituitarism.

DESIGN

Nonfamilial patients (724) with either SOD (n = 314) or isolated pituitary dysfunction, optic nerve hypoplasia, or midline neurological abnormalities (n = 410) originally screened by SSCP were rescreened by heteroduplex detection for mutations in the coding and regulatory regions of HESX1. In addition, direct sequencing of HESX1 was performed in 126 patients with familial hypopituitarism from 66 unrelated families and in 11 patients born to consanguineous parents.

PATIENTS

All patients studied had at least one of the three classical features associated with SOD (optic nerve hypoplasia, hypopituitarism, midline forebrain defects).

RESULTS

Novel sequence changes identified included a functionally significant heterozygous mutation at a highly conserved residue (E149K) in a patient with isolated GH deficiency and digital abnormalities. The overall incidence of coding region mutations within the cohort was less than 1%.

CONCLUSIONS

Mutations within HESX1 are a rare cause of SOD and hypopituitarism. However, the large number of familial patients with SOD in whom no mutations were identified is suggestive of an etiological role for other genetic factors. Furthermore, we have found that within our cohort SOD is associated with a reduced maternal age compared with isolated defects of the hypothalamopituitary axis.