Posterior polymorphous corneal dystrophy 3 is associated with agenesis and hypoplasia of the corpus callosum

Poor intraoperative visibility and postoperative astigmatism associated with trabecular micro-bypass stent for corneal dystrophy: A case report

RATIONALE

There are reports of safe cataract surgery in eyes with posterior polymorphous corneal dystrophy (PPCD); however, to our knowledge, there are no reports of minimally invasive glaucoma surgery (MIGS) in eyes with PPCD. Herein, we report a case of poor intraoperative visibility with gonioscopy, postoperative corneal edema, and corneal astigmatism in eyes with PPCD treated with trabecular micro-bypass stent combined with cataract surgery.

PATIENT CONCERNS/DIAGNOSIS

A 78-year-old man was referred to our hospital for MIGS. He presented with bilateral corneal endothelial vesicular changes and band lesions. Endothelial cell density was 2983/2871 cells/mm2 (right/left eye), central corneal thickness was 581 μm/572 μm, best-corrected visual acuity values (Snellen equivalent) were 20/32 (right) and 20/100 (left), and corneal astigmatism was -2.7D in the right eye and -2.5D in the left eye.

INTERVENSIONS/ OUTCOMS

After phacoemulsification and aspiration with intraocular lens implantation with a 2.4-mm corneal incision in both eyes, trabecular micro-bypass stents were inserted successfully despite the poor intraoperative visibility with gonioscopy. One week after surgery, the central corneal thickness was 614 μm/609 μm, and Descemet's membrane folds and mild corneal edema were observed. Best-corrected decimal visual acuity was 20/40 for the right eye and 20/50 for the left eye. In the left eye, total corneal astigmatism increased from -2.5D to -5.5D. Corneal astigmatism and edema showed gradual improvement.

LESSONS

Although reports have shown that cataract surgery can be safely performed in eyes with PPCD, MIGS in eyes with PPCD may require caution regarding intraoperative visibility with gonioscopy and visual function in the early postoperative period.

Loss-of-function variants in ZEB1 cause dominant anomalies of the corpus callosum with favourable cognitive prognosis

BACKGROUND

The neurodevelopmental prognosis of anomalies of the corpus callosum (ACC), one of the most frequent brain malformations, varies extremely, ranging from normal development to profound intellectual disability (ID). Numerous genes are known to cause syndromic ACC with ID, whereas the genetics of ACC without ID remains poorly deciphered.

METHODS

Through a collaborative work, we describe here ZEB1, a gene previously involved in an ophthalmological condition called type 3 posterior polymorphous corneal dystrophy, as a new dominant gene of ACC. We report a series of nine individuals with ACC (including three fetuses terminated due to ACC) carrying a ZEB1 heterozygous loss-of-function (LoF) variant, identified by exome sequencing.

RESULTS

In five cases, the variant was inherited from a parent with a normal corpus callosum, which illustrates the incomplete penetrance of ACC in individuals with an LoF in ZEB1. All patients reported normal schooling and none of them had ID. Neuropsychological assessment in six patients showed either normal functioning or heterogeneous cognition. Moreover, two patients had a bicornuate uterus, three had a cardiovascular anomaly and four had macrocephaly at birth, which suggests a larger spectrum of malformations related to ZEB1.

CONCLUSION

This study shows ZEB1 LoF variants cause dominantly inherited ACC without ID and extends the extraocular phenotype related to this gene.

Systematic review of SLC4A11, ZEB1, LOXHD1, and AGBL1 variants in the development of Fuchs' endothelial corneal dystrophy

Introduction

The pathogenic role of variants in TCF4 and COL8A2 in causing Fuchs' endothelial corneal dystrophy (FECD) is not controversial and has been confirmed by numerous studies. The causal role of other genes, SLC4A11, ZEB1, LOXHD1, and AGBL1, which have been reported to be associated with FECD, is more complicated and less obvious. We performed a systematic review of the variants in the above-mentioned genes in FECD cases, taking into account the currently available population frequency information, transcriptomic data, and the results of functional studies to assess their pathogenicity.

Methods

Search for articles published in 2005-2022 was performed manually between July 2022 and February 2023. We searched for original research articles in peer-reviewed journals, written in English. Variants in the genes of interest identified in patients with FECD were extracted for the analysis. We classified each presented variant by pathogenicity status according to the ACMG criteria implemented in the Varsome tool. Diagnosis, segregation data, presence of affected relatives, functional analysis results, and gene expression in the corneal endothelium were taken into account. Data on the expression of genes of interest in the corneal endothelium were extracted from articles in which transcriptome analysis was performed. The identification of at least one variant in a gene classified as pathogenic or significantly associated with FECD was required to confirm the causal role of the gene in FECD.

Results

The analysis included 34 articles with 102 unique ZEB1 variants, 20 articles with 64 SLC4A11 variants, six articles with 26 LOXHD1 variants, and five articles with four AGBL1 variants. Pathogenic status was confirmed for seven SLC4A11 variants found in FECD. No variants in ZEB1, LOXHD1, and AGBL1 genes were classified as pathogenic for FECD. According to the transcriptome data, AGBL1 and LOXHD1 were not expressed in the corneal endothelium. Functional evidence for the association of LOXHD1, and AGBL1 with FECD was conflicting.

Conclusion

Our analysis confirmed the causal role of SLC4A11 variants in the development of FECD. The causal role of ZEB1, LOXHD1, and AGBL1 variants in FECD has not been confirmed. Further evidence from familial cases and functional analysis is needed to confirm their causal roles in FECD.

The role of the ZEB1–neuroinflammation axis in CNS disorders

Zinc finger E-box binding homeobox 1 (ZEB1) is a master modulator of the epithelial–mesenchymal transition (EMT), a process whereby epithelial cells undergo a series of molecular changes and express certain characteristics of mesenchymal cells. ZEB1, in association with other EMT transcription factors, promotes neuroinflammation through changes in the production of inflammatory mediators, the morphology and function of immune cells, and multiple signaling pathways that mediate the inflammatory response. The ZEB1–neuroinflammation axis plays a pivotal role in the pathogenesis of different CNS disorders, such as brain tumors, multiple sclerosis, cerebrovascular diseases, and neuropathic pain, by promoting tumor cell proliferation and invasiveness, formation of the hostile inflammatory micromilieu surrounding neuronal tissues, dysfunction of microglia and astrocytes, impairment of angiogenesis, and dysfunction of the blood–brain barrier. Future studies are needed to elucidate whether the ZEB1–neuroinflammation axis could serve as a diagnostic, prognostic, and/or therapeutic target for CNS disorders.

Update on the genetics of corneal endothelial dystrophies

Corneal endothelial dystrophies are a heterogeneous group of diseases with different modes of inheritance and genetic basis for each dystrophy. The genes associated with these diseases encode transcription factors, structural components of the stroma and Descemet membrane, cell transport proteins, and others. Congenital hereditary endothelial dystrophy (CHED) is associated with mutations in two genes, OVOL2 and SLC4A11, for dominant and recessive forms of CHED, respectively. Mutations in three genes are known to cause posterior polymorphous corneal dystrophy (PPCD). They are OVOL2 (PPCD1), ZEB1 (PPCD3), and GRHL1 (PPCD4). The PPCD2 locus involving the collagen gene COL8A2 on chromosome 1 is disputed due to insufficient evidence. Mutations in the COL8A2 gene are associated with early-onset Fuchs’ endothelial corneal dystrophy (FECD). Several genes have been associated with the more common, late-onset FECD. Alterations in each of these genes occur in a fraction of patients, and the most prevalent genetic alteration in FECD patients across the world is a triplet repeat expansion in the TCF4 gene. Knowledge of the genetics of corneal endothelial dystrophies has considerably advanced within the last decade and has contributed to better diagnosis of these dystrophies as well as opened up the possibility of novel therapeutic approaches based on the molecular mechanisms involved. The functions of genes identified to date provide insights into the pathogenic mechanisms involved in each disorder.

Non-Penetrance for Ocular Phenotype in Two Individuals Carrying Heterozygous Loss-of-Function ZEB1 Alleles

ZEB1 loss-of-function (LoF) alleles are known to cause a rare autosomal dominant disorder—posterior polymorphous corneal dystrophy type 3 (PPCD3). To date, 50 pathogenic LoF variants have been identified as disease-causing and familial studies have indicated that the PPCD3 phenotype is penetrant in approximately 95% of carriers. In this study, we interrogated in-house exomes (n = 3616) and genomes (n = 88) for the presence of putative heterozygous LoF variants in ZEB1. Next, we performed detailed phenotyping in a father and his son who carried a novel LoF c.1279C>T; p.(Glu427*) variant in ZEB1 (NM_030751.6) absent from the gnomAD v.2.1.1 dataset. Ocular examination of the two subjects did not show any abnormalities characteristic of PPCD3. GnomAD (n = 141,456 subjects) was also interrogated for LoF ZEB1 variants, notably 8 distinct heterozygous changes presumed to lead to ZEB1 haploinsufficiency, not reported to be associated with PPCD3, have been identified. The NM_030751.6 transcript has a pLI score ≥ 0.99, indicating extreme intolerance to haploinsufficiency. In conclusion, ZEB1 LoF variants are present in a general population at an extremely low frequency. As PPCD3 can be asymptomatic, the true penetrance of ZEB1 LoF variants remains currently unknown but is likely to be lower than estimated by the familial led approaches adopted to date.

Expression and Function of ZEB1 in the Cornea

ZEB1 is an important transcription factor for epithelial to mesenchymal transition (EMT) and in the regulation of cell differentiation and transformation. In the cornea, ZEB1 presents in all three layers: the epithelium, the stroma and the endothelium. Mutations of ZEB1 have been linked to multiple corneal genetic defects, particularly to the corneal dystrophies including keratoconus (KD), Fuchs endothelial corneal dystrophy (FECD), and posterior polymorphous corneal dystrophy (PPCD). Accumulating evidence indicates that dysfunction of ZEB1 may affect corneal stem cell homeostasis, and cause corneal cell apoptosis, stromal fibrosis, angiogenesis, squamous metaplasia. Understanding how ZEB1 regulates the initiation and progression of these disorders will help us in targeting ZEB1 for potential avenues to generate therapeutics to treat various ZEB1-related disorders.

Altered white matter integrity in patients with monocular blindness: A diffusion tensor imaging and tract-based spatial statistics study

BACKGROUND

Visual deprivation can lead to abnormal and plastic changes in the brain's visual system and other systems. Although the secondary changes of gray matter in patients have been well studied, the study of white matter is rare. In fact, subtle changes in white matter may be revealed by diffusion tensor imaging, and tract-based spatial statistics can be used to analyze DTI image data.

PURPOSE

In the present study, diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) were used to investigate abnormal structural changes in the white matter (WM) of patients with monocular blindness (MB).

METHODS

We recruited 16 healthy controls (HC) (fourteen males and two females) and 16 patients (fifteen males and one female) with right-eye blindness (without differences in left-eye vision). All patients were of similar age. Data acquisition was performed using magnetic resonance imaging (MRI) and DTI. Voxel-based whole brain comparisons of fractional anisotropy (FA) and radial diffusivity (RD) of WM fibers in patients and HC were performed using the TBSS method. The mean FA and RD values for altered brain regions in MB patients were analyzed via the receiver operating characteristic (ROC) curve. Correlation analysis was performed to investigate the relationships between the average FA (RD) value of the whole brain and anxiety score, depression score, and visual function questionnaire score in MB patients.

RESULTS

In MB patients, the mean FA of the whole brain was decreased versus HC. Moreover, the FA values of the corpus callosum, the corona radiata, the posterior thalamic radiation, and the right retrolenticular part of internal capsule were significantly decreased. In addition, the average RD value of the whole brain in MB patients was higher than that observed in HC. The mean FA and RD values of brain regions were analyzed using the ROC curve, and the results showed that the area under the ROC curve was more accurate. Furthermore, the average FA and RD values of the whole brain were significantly correlated with anxiety score, depression score, and visual function-related quality of life score.

CONCLUSION

DTI and TBSS may be useful in examining abnormal spontaneous alterations in the WM of MB patients. The observed changes in FA and RD values may imply the larvaceous neurological mechanism involved in MB.

ZEB1 Represses Neural Differentiation and Cooperates with CTBP2 to Dynamically Regulate Cell Migration during Neocortex Development

Zinc-finger E-box binding homeobox 1 (Zeb1) is a key regulator of epithelial-mesenchymal transition and cancer metastasis. Mutation of ZEB1 is associated with human diseases and defective brain development. Here we show that downregulation of Zeb1 expression in embryonic cortical neural progenitor cells (NPCs) is necessary for proper neuronal differentiation and migration. Overexpression of Zeb1 during neuronal differentiation, when its expression normally declines, blocks NPC lineage progression and disrupts multipolar-to-bipolar transition of differentiating neurons, leading to severe migration defects and subcortical heterotopia bands at postnatal stages. ZEB1 regulates a cohort of genes involved in cell differentiation and migration, including Neurod1 and Pard6b. The interaction between ZEB1 and CTBP2 in the embryonic cerebral cortex is required for ZEB1 to elicit its effect on the multipolar-to-bipolar transition, but not its suppression of Neurod1. These findings provide insights into understanding the complexity of transcriptional regulation during neuronal differentiation.

The utility of massively parallel sequencing for posterior polymorphous corneal dystrophy type 3 molecular diagnosis

The aim of this study was to identify the molecular genetic cause of disease in posterior polymorphous corneal dystrophy (PPCD) probands of diverse origin and to assess the utility of massively parallel sequencing in the detection of ZEB1 mutations. We investigated a total of 12 families (five British, four Czech, one Slovak and two Swiss). Ten novel and two recurrent disease-causing mutations in ZEB1, were identified in probands by Sanger (n = 5), exome (n = 4) and genome (n = 3) sequencing. Sanger sequencing was used to confirm the mutations detected by massively parallel sequencing, and to perform segregation analysis. Genome sequencing revealed that one proband harboured a novel ∼0.34 Mb heterozygous de novo deletion spanning exons 1-7 and part of exon 8. Transcript analysis confirmed that the ZEB1 transcript is detectable in blood-derived RNA samples and that the disease-associated variant c.482-2A>G leads to aberrant pre-mRNA splicing. De novo mutations, which are a feature of PPCD3, were found in the current study with an incidence rate of at least 16.6%. In general, massively parallel sequencing is a time-efficient way to detect PPCD3-associated mutations and, importantly, genome sequencing enables the identification of full or partial heterozygous ZEB1 deletions that can evade detection by both Sanger and exome sequencing. These findings contribute to our understanding of PPCD3, for which currently, 49 pathogenic variants have been identified, all of which are predicted to be null alleles.

Agenesis of the corpus callosum, developmental delay, autism spectrum disorder, facial dysmorphism, and posterior polymorphous corneal dystrophy associated with ZEB1 gene deletion

We report on a girl diagnosed prenatally with agenesis of the corpus callosum (ACC) on fetal ultrasound and MRI. On postnatal follow-up she was noted to have developmental delay, facial dysmorphism, autism spectrum disorder, and posterior polymorphous corneal dystrophy (PPD). Array-comparative genomic hybridization analysis (Array-CGH) showed a 2.05 Mb de novo interstitial deletion at 10p11.23p11.22. The deleted region overlaps 1 OMIM Morbid Map gene, ZEB1 (the zinc finger E-box binding homeobox transcription factor 1), previously associated with posterior polymorphous corneal dystrophy type 3 (PPCD3). To our best knowledge this is the first reported case with a deletion of the ZEB1 gene in an individual with ACC and PPD, showing that the haploinsufficiency of the ZEB1 is likely the cause of our patient's phenotype.

Copy Number Variations Found in Patients with a Corpus Callosum Abnormality and Intellectual Disability

OBJECTIVE

To evaluate the role that chromosomal micro-rearrangements play in patients with both corpus callosum abnormality and intellectual disability, we analyzed copy number variations (CNVs) in patients with corpus callosum abnormality/intellectual disability STUDY DESIGN: We screened 149 patients with corpus callosum abnormality/intellectual disability using Illumina SNP arrays.

RESULTS

In 20 patients (13%), we have identified at least 1 CNV that likely contributes to corpus callosum abnormality/intellectual disability phenotype. We confirmed that the most common rearrangement in corpus callosum abnormality/intellectual disability is inverted duplication with terminal deletion of the 8p chromosome (3.2%). In addition to the identification of known recurrent CNVs, such as deletions 6qter, 18q21 (including TCF4), 1q43q44, 17p13.3, 14q12, 3q13, 3p26, and 3q26 (including SOX2), our analysis allowed us to refine the 2 known critical regions associated with 8q21.1 deletion and 19p13.1 duplication relevant for corpus callosum abnormality; report a novel 10p12 deletion including ZEB1 recently implicated in corpus callosum abnormality with corneal dystrophy; and) report a novel pathogenic 7q36 duplication encompassing SHH. In addition, 66 variants of unknown significance were identified in 57 patients encompassed candidate genes.

CONCLUSIONS

Our results confirm the relevance of using microarray analysis as first line test in patients with corpus callosum abnormality/intellectual disability.

Unilateral Posterior Polymorphous Corneal Dystrophy Presented as Anisometropic Astigmatism: 3 Case Reports

Background

Posterior polymorphous corneal dystrophy (PPCD) is typically considered bilateral and asymptomatic. However, few case reports on patients with unilateral PPCD with asymmetric refractive error have mentioned anisometropic amblyopia development. In support of this, we report 3 cases of unilateral PPCD that presented as anisometropic astigmatism. Visual prognosis related to amblyopia development is discussed.

Case Presentation

All 3 patients had a band lesion in the affected eye and a difference of at least 1.5 diopters in cylindrical refractive error between their eyes. The affected eye had a greater amount of astigmatism in all cases. Two patients (Cases 1 and 2) also had amblyopia in the affected eye. Case 1 was a 25-year-old male with a unilateral PPCD diagnosis and a band lesion involving the visual axis. Case 2 was an 11-year-old boy diagnosed with unilateral PPCD. The boy was treated with occlusion and atropine therapy over a 2-year period. Case 3 was a 4-year-old girl diagnosed with unilateral PPCD. The girl had a 30-month history of corrective spectacle use and had no amblyopia. In all cases, the corneal endothelial cell count was lower in the affected eye than in the unaffected contralateral eye.

Conclusions

Practitioners should closely monitor patients with unilateral PPCD for astigmatic anisometropia and amblyopia development. Visual prognosis for patients with unilateral PPCD may be related to lesion position, age at diagnosis, astigmatism severity, and early-childhood corrective spectacle use.

Clinical characterization of posterior polymorphous corneal dystrophy in patients of Indian ethnicity

PURPOSE

To characterize the clinical presentation of posterior polymorphous corneal dystrophy (PPCD) in eyes of Indian ethnicity.

DESIGN

Retrospective cohort study from January 1995 to December 2015.

PARTICIPANTS

Patients with the diagnosis of posterior polymorphous corneal dystrophy.

METHODS

Medical records of the patients were reviewed for clinical presentation. Histology of corneal specimens of those that underwent keratoplasty was assessed.

MAIN OUTCOME MEASURES

Descriptive analysis of clinical condition.

RESULTS

Mean age at first evaluation was 32.5 years (range 1-73 years), male:female = 35:18. Majority (44/53; 83 %) of the patients had bilateral involvement. 5/9 (44 %) patients with unilateral presentation were amblyopic in the affected eye. The clinical features documented were vesicles in 94 eyes, band-like pattern in 32 eyes, edema of varying degree in 23 eyes (12 patients, 1 patient was one eyed), and anterior segment changes in 1 eye. 8/45 (17 %) eyes had a regular astigmatism with steep axis >47 D (range 47.2-56.2 D). 16 eyes of 12 patients who had clinically evident corneal edema underwent keratoplasty. Mean age at keratoplasty was 58 years (range 1-73 years). 8 patients had penetrating keratoplasty (PK) and 8 had Descemet stripping endothelial keratoplasty (DSEK). Mean follow-up after keratoplasty was 4.2 years (1 month to 13 years). Except one, all grafts remained clear till the last follow-up. In all specimens, the Descemet membrane was grossly thickened.

CONCLUSIONS

In our study, 12/53 (22.6 %) patients required keratoplasty for visually significant corneal edema. Except one, all were older adults. The patients who needed keratoplasty were bilaterally afflicted and had visually significant cornea edema in both eyes. With a mean follow-up duration of 4.2 years after keratoplasty, no recurrences were noted.

Identification of the First De Novo UBIAD1 Gene Mutation Associated with Schnyder Corneal Dystrophy

Purpose. To report the identification of the first de novo UBIAD1 missense mutation in an individual with Schnyder corneal dystrophy (SCD). Methods. A slit lamp examination was performed on a 47-year-old woman without a family history of corneal disorders. The proband's parents, two sisters, and son were also examined and genomic DNA from all six individuals was collected. The exons and exon-intron boundaries of UBIAD1 were screened using Sanger sequencing. Identified mutations were screened for in 200 control chromosomes. In silico analysis predicted the impact of identified mutations on protein function and structure. Results. Slit lamp examination of the proband revealed findings consistent with SCD. Corneas of the family members appeared unaffected. Screening of UBIAD1 in the proband identified a novel heterozygous c.308C>T mutation, predicted to encode the missense amino acid substitution p.(Thr103Ile). This mutation was not identified in any of the family members or in 200 control chromosomes and was predicted to be damaging to normal protein function and structure. Conclusions. We present a novel heterozygous de novo missense mutation in UBIAD1, p.(Thr103Ile), identified in a patient with classic clinical features of SCD. This highlights the value of genetic testing in clinical diagnostic settings, even in the absence of a positive family history.

Identification of presumed pathogenic KRT3 and KRT12 gene mutations associated with Meesmann corneal dystrophy

PURPOSE

To report potentially pathogenic mutations in the keratin 3 (KRT3) and keratin 12 (KRT12) genes in two individuals with clinically diagnosed Meesmann corneal dystrophy (MECD).

METHODS

Slit-lamp examination was performed on the probands and available family members to identify characteristic features of MECD. After informed consent was obtained, saliva samples were obtained as a source of genomic DNA, and screening of KRT3 and KRT12 was performed. Potentially pathogenic variants were screened for in 200 control chromosomes. PolyPhen-2, SIFT, and PANTHER were used to predict the functional impact of identified variants. Short tandem repeat genotyping was performed to confirm paternity.

RESULTS

Slit-lamp examination of the first proband demonstrated bilateral, diffusely distributed, clear epithelial microcysts, consistent with MECD. Screening of KRT3 revealed a heterozygous missense variant in exon 1, c.250C>T (p.(Arg84Trp)), which has a minor allele frequency of 0.0076 and was not identified in 200 control chromosomes. In silico analysis with PolyPhen-2 and PANTHER predicted the variant to be damaging to protein function; however, SIFT analysis predicted tolerance of the variant. The second proband demonstrated bilateral, diffusely distributed epithelial opacities that appeared gray-white on direct illumination and translucent on retroillumination. Neither parent demonstrated corneal opacities. Screening of KRT12 revealed a novel heterozygous insertion/deletion variant in exon 6, c.1288_1293delinsAGCCCT (p.(Arg430_Arg431delinsSerPro)). This variant was not present in either of the proband's parents or in 200 control chromosomes and was predicted to be damaging by PolyPhen-2, PANTHER, and SIFT. Haplotype analysis confirmed paternity of the second proband, indicating that the variant arose de novo.

CONCLUSIONS

We present a novel KRT12 mutation, representing the first de novo mutation and the first indel in KRT12 associated with MECD. In addition, we report a variant of uncertain significance in KRT3 in an individual with MECD. Although the potential pathogenicity of this variant is unknown, it is the first variant affecting the head domain of K3 to be reported in an individual with MECD and suggests that disease-causing variants associated with MECD may not be restricted to primary sequence alterations of either the helix-initiation or helix-termination motifs of K3 and K12.

Identification of six novel mutations in ZEB1 and description of the associated phenotypes in patients with posterior polymorphous corneal dystrophy 3

Posterior polymorphous corneal dystrophy 3 (PPCD3) is a rare autosomal dominant disorder caused by mutations in ZEB1. To date all identified disease-causing variants were unique to the studied families, except for c.1576dup. We have detected six novel ZEB1 mutations; c.1749_1750del; p.(Pro584*) and c.1717_1718del; p.(Val573Phefs*12) in two Czech families, c.1176dup; p.(Ala393Serfs*19), c.1100C>A; p.(Ser367*), c.627del; p.(Phe209Leufs*11) in three British families and a splice site mutation, c.685-2A>G, in a patient of Sri Lankan origin. An additional British proband had the c.1576dup; p.(Val526Glyfs*3) mutation previously reported in other populations. Clinical findings were variable and included bilateral congenital corneal opacity in one proband, development of opacity before the age of 2 years in another individual and bilateral iris flocculi in yet another subject. The majority of eyes examined by corneal topography (10 out of 16) had an abnormally steep cornea (flat keratometry 46.5-52.7 diopters, steep keratometry 48.1-54.0 diopters). One proband underwent surgery for cryptorchidism. Our study further demonstrates that PPCD3 can present as corneal edema in early childhood, and that an abnormally steep keratometry is a common feature of this condition. As cryptorchidism has been previously observed in two other PPCD3 cases, its association with the disease warrants further investigation.