Developmental genes and ocular malformation syndromes

Distinguishing risk factors between congenital anophthalmia and microphthalmia using multivariable logistic regression

Background

Etiologies of congenital microphthalmia and anophthalmia are unclear and commonly thought to be homogenous. To test if risk factors are similar for these two diseases, we compared the risk factors between congenital microphthalmia and anophthalmia in a large Chinese cohort.

Methods

A total of 347 patients with congenital microphthalmia or anophthalmia diagnosed by magnetic resonance imaging (MRI), computed tomography (CT) or ultrasound from 2011 to 2018 were enrolled. Patients’ clinical information, used as potential risk factors, was retrospectively collected. A multivariable logistic regression model was used to estimate odds ratios (OR) and 95% confidence intervals (CI).

Results

A total of 347 patients were affected by congenital microphthalmia or anophthalmia. A total of 324 cases were microphthalmia, and 23 cases were anophthalmia. Structural abnormalities, mother’s age at initial pregnancy, whether the mother drinks, whether the mother was diseased during pregnancy and whether the father has systemic disease passed the univariate test. In the multivariable logistic regression model, whether the mother was diseased during pregnancy (OR =2.804, P=0.023) and whether the father had systemic disease (OR =4.795, P=0.027) are significant risk factors for anophthalmia over microphthalmia. Influenza or common cold infection accounted most of the mother’s diseases during pregnancy.

Conclusions

Mothers with diseases, mainly influenza or common cold infection, during pregnancy are more likely to have baby with anophthalmia than microphthalmia. Our study indicated that there might be different etiologies for anophthalmia and microphthalmia.

Epidemiology of anophthalmia and microphthalmia: Prevalence and patterns in Texas, 1999-2009

Anophthalmia and microphthalmia are a set of rare, yet severe, birth defects considered to be part of a spectrum of developmental ocular malformations ranging from smaller than average to completely absent eyes. Despite their clinical significance, little is known about the etiologies of these conditions. The goal of this study was to expand our understanding of the epidemiology of anophthalmia and microphthalmia. Data for this population-based assessment were obtained from the Texas Birth Defects Registry (TBDR) and Center for Health Statistics for the period 1999-2009. Descriptive analyses and estimates of birth prevalence and prevalence ratios (PR) were determined for this defect. There were 1,262 definite anophthalmia and microphthalmia patients identified in the TBDR, with an overall combined prevalence of 3.0 per 10,000 live births. More than half (55.7%) of the patients had at least one chromosome abnormality or syndrome. In addition, 92.4% of nonsyndromic patients (i.e., have no recorded chromosome abnormalities or syndromes) had at least one additional birth defect. After adjustment for multiple factors, the prevalence of nonsyndromic anophthalmia and microphthalmia was higher among mothers who had ≥2 previous fetal deaths (PR = 1.43, 95% confidence interval [CI]: 1.03-1.97) and among mothers with any reported diabetes (PR = 2.08, 95% CI: 1.49-2.90). Our results confirm that children with anophthalmia and microphthalmia frequently have genetic syndromes or are born with other major birth defects. Our findings add to the limited body of literature on anophthalmia and microphthalmia as well as help define subgroups of women who are more likely to have children with this malformation.

Transgenic models for eye malformations

Several lines of transgenic mice developing eye malformations have been described in the literature and appear to be of increasing interest for the study of eye teratology in humans, since gene expression and regulation can be studied in the developing animal. Transgenic applications are briefly described here and an overview of existing transgenic mouse models carrying different eye abnormalities is given according to the major diagnosis (e.g., cataract, microphthalmia, anterior segment dysgenesis, retinal dysplasia). Interestingly, many transgenic models exhibit pathological findings similar to those observed in human pediatric ophthalmology. Unfortunately, detailed embryological studies in transgenic mice bearing congenital eye malformations are not available for all lines. Thus, the importance of creating further transgenic models to study the function of morphogenes and growth factors in eye development is also discussed.