12-year follow-up of the first endothelial keratoplasty without Descemet stripping in a 3-month newborn with Congenital Hereditary Endothelial Dystrophy (CHED)

BACKGROUND

Endothelial Keratoplasty (EK) is now considered as the standard treatment for Congenital Hereditary Endothelial Dystrophy (CHED) by many surgeons. We present the 12-year clinical outcome of the youngest operated patient with CHED in which we successfully performed a bilateral EK procedure without removing the recipient endothelium-Descemet complex.

CASE PRESENTATION

In November 2010 we performed EK without Descemet Stripping in a 3-month female newborn, thinking that the lower manipulation obtained by leaving the recipient endothelium-Descemet complex could be the key factor for the success of our surgery. Such a particular technique was new in newborns. The surgery was a success, but the long-term visual result was not predictable at that time. We followed the patient at 4 months, and then yearly. At the latest visit in October 2022 the visual, cognitive, and motorial developments were normal, with Best-corrected Distance Visual Acuity of 0.4 LogMAR with - 0.75 D sf + 2.75 D cyl @ 105° in the right eye (RE) and 0.4 LogMAR with + 1.50 D sf + 2.50 D cyl @ 60° in the left eye (LE). The endothelial microscope showed an unexpected healthy endothelium, with a cell count of 2383 cells/mm2 in the RE and of 2547 cells/mm2 in the LE from a starting donor count of 2900 cells/mm2. No secondary procedures were performed during the 12-year follow-up.

CONCLUSION

EK without Descemet stripping has proved to be a successful procedure over time in our newborn. The unexpected healthy endothelium suggests a role of the Descemet membrane in CHED.

Updates on congenital hereditary endothelial dystrophy

Congenital hereditary endothelial dystrophy (CHED) is a rare genetic corneal disorder causing progressive cornea clouding and significant visual impairment. CHED remains a leading indication for pediatric corneal transplantation despite its infrequency, particularly in regions with high consanguinity rates like Southeast Asia. Identifying the Solute Carrier Family 4 Member 11 (SLC4A11) gene as the genetic basis of CHED has led to the discovery of it's various genetic variations. However, a comprehensive understanding of its clinical-genetic correlation, pathophysiology, and optimal management is ongoing. This review aims to consolidate current knowledge about CHED, covering its genetic origins, pathophysiological mechanisms, clinical presentation, and management strategies. Surgical intervention, such as penetrating keratoplasty (PK), Descemet stripping automated endothelial keratoplasty (DSAEK), and Descemet membrane endothelial keratoplasty (DMEK), remains the primary treatment. DSAEK and DMEK offer advantages over PK, including quicker visual recovery, reduced complications, and longer graft survival, especially in the pediatric age group. The timing of surgical interventions depends on disease severity, age at presentation, comorbidities, and visual potential. Elevated oxidative stress in CHED corneal tissue suggests potential benefits from anti-inflammatory drugs to rescue mutated endothelial cells. Considering the limitations of corneal graft surgeries, exploring novel gene-based molecular therapies are essential for future management. Early diagnosis, appropriate surgical interventions, amblyopia control, and genetic counseling for predictive analysis are pivotal for optimizing CHED management. A multidisciplinary approach involving ophthalmologists, researchers, and genetic counselors is essential for precise diagnosis and optimal care for CHED patients.

A review of techniques and outcomes of endothelial keratoplasty in congenital hereditary endothelial dystrophy

Congenital hereditary endothelial dystrophy affects the Descemet membrane and endothelium, resulting in corneal decompensation. Penetrating keratoplasty (PKP) has been the gold-standard surgical management until recently; however, at present, endothelial keratoplasty (DSEK/DSAEK/n-DSEK: Descemet-stripping or non-Descemet stripping endothelial keratoplasty and DMEK/n-DMEK: Descemet membrane endothelial keratoplasty) is being preferred due to lesser intraoperative and postoperative complications, early visual recovery, and comparable visual outcomes. Endothelial keratoplasty (EK) can be challenging, especially in pediatric eyes with CHED due to smaller eyeballs, shallow anterior chambers, phakic status, and poor intraoperative visibility due to thick and hazy corneas. A total of 198 articles matched our search strategy. After screening for duplication and going through the titles and abstracts, 12 relevant original articles, one case series, and six case reports were included in this review. Various surgical modifications have to be adopted in comparison to adult eyes to overcome the aforementioned difficulties. Regardless, studies have shown favorable visual outcomes with better graft survival and fewer complications in eyes that underwent EK compared to PKP. Hence, timely surgical intervention and strict amblyopia management can result in better final visual outcomes. The purpose of this review is to summarize various intraoperative difficulties and the surgical modifications required, different surgical techniques, visual and graft-related outcomes, and various complications of EK in CHED eyes.

Rescue of the Congenital Hereditary Endothelial Dystrophy Mouse Model by Adeno-Associated Viruse-Mediated Slc4a11 Replacement

Purpose

Congenital hereditary endothelial dystrophy (CHED) is a rare condition that manifests at an early age showing corneal edema, increased oxidative stress, mitochondrial dysfunction, and eventually apoptosis of the endothelium due to loss of function of the membrane transport protein SLC4A11. This project tested whether replacing Slc4a11 into the Slc4a11 -/- CHED mouse model can reverse the disease-associated phenotypes.

Design

Experimental study.

Participants

Five-week-old or 11-week-old Slc4a11 -/- mice. Age- and gender-matched Slc4a11 +/+ animals were used as controls. A total of 124 animals (62 female, and 62 male) were used in this study. Fifty-three animals of the genotype Slc4a11 +/+ were used as age- and gender-matched noninjected controls. Seventy-one Slc4a11 -/- mice were administered anterior chamber injections of adeno-associated virus (AAV).

Methods

Anterior chambers of young (5 weeks old) or older (11 weeks old) Slc4a11 -/- mice were injected once with adeno-associated virus serotype 9 (AAV9) mouse Slc4a11 or AAV9-Null vectors. Corneal thickness was measured using OCT. End point analysis included corneal endothelial cell density, mitochondrial oxidative stress, and corneal lactate concentration.

Main Outcome Measures

Corneal thickness, endothelial cell loss, lactate levels, and mitochondrial oxidative stress.

Results

In the young animals, AAV9-Slc4a11 reversed corneal edema, endothelial cell loss, mitochondrial oxidative stress, lactate transporter expression, and corneal lactate concentration to the levels observed in wild-type animals. In the older animals, gene replacement did not reverse the phenotype but prevented progression.

Conclusions

Functional rescue of CHED phenotypes in the Slc4a11 -/- mouse is possible; however, early intervention is critical.

Whole exome sequencing identified FAM149A as a plausible causative gene for congenital hereditary endothelial dystrophy, affecting Nrf2-Antioxidant signaling upon oxidative stress

BACKGROUND

Congenital hereditary endothelial dystrophy (CHED) is a rare genetic disease of the corneal endothelium with a very early onset of bilateral corneal edema due to degeneration and dysfunction of the corneal endothelium. Currently SLC4A11 is the only established causative gene for CHED, but not all these reported CHED patients could be explained by SLC4A11 deficiency, indicating that the genetic predisposition of CHED still requires further exploration.

METHODS

Trio-based whole-exome sequencing was performed on a CHED patient and his unaffected parents. The GATK2 and an in-house bioinformatics pipeline were applied for variant analyses, following the 2015 American College of Medical Genetics and Genomics (ACMG) guidelines. Potential pathogenic variants were further validated by Sanger sequencing. The expression profiles of FAM149A in cell line, murine tissues or human corneal endothelia were determined by RT-qPCR. Small interfering RNA was used to knock down the expression of FAM149A in vitro. Cell viability was detected by a CCK-8 assay. ROS and 8-OHdG were examined by fluorometric analysis. The nuclear translocation of NRF2 was determined by western blotting.

RESULTS

We identified a homozygous mutation (NM_015398.3: c.991A > G; p.R331G) in the FAM149A gene that related to the phenotype of CHED. FAM149A was found to be highly expressed in corneal endothelium, and up-regulated upon oxidative stress. Further functional investigations demonstrated that deficiency in FAM149A impaired Nrf2-antioxidant signaling, rendering cells more vulnerable to oxidative stress. Consistently, the expression of FAM149A was significantly reduced in patients with corneal endothelium dysfunction.

CONCLUSION

This study demonstrated, for the first time, FAM149A as a plausible causative gene for CHED etiology, offering new insight for future investigation targeting CHED.

Homozygous SLC4A11 mutation in a large Irish CHED2 pedigree

BACKGROUND

Congenital hereditary endothelial dystrophy (CHED) is a genetic disorder of corneal endothelial cells resulting in corneal clouding and visual impairment. Autosomal dominant (CHED1) and autosomal recessive (CHED2) forms have been reported and map to distinct loci on chromosome 20. CHED2 is caused by mutations in the SLC4A11 gene which encodes a membrane transporter protein.

MATERIALS AND METHODS

Members of a large CHED2 family were recruited for clinical and genetic studies. Genomic DNA was sequenced for the exons and intron-exon boundaries of the SLC4A11 gene.

RESULTS

Twelve family members were recruited, of which eight were diagnosed with CHED. A homozygous SLC4A11 mutation (Leu843Pro) was detected in the eight patients; a single copy of the mutation was present in three unaffected carriers.

CONCLUSIONS

A missense SLC4A11 mutation (Leu843Pro) is responsible for CHED2 in this family; this is the first report of this mutation in a homozygous state.

Fuchs Endothelial Corneal Dystrophy in a Heterozygous Carrier of Congenital Hereditary Endothelial Dystrophy Type 2 with a Novel Mutation in SLC4A11

PURPOSE

Congenital hereditary endothelial dystrophy (CHED) is a rare genetic disorder caused by mutations in corneal endothelial cells. CHED can be divided into 2 types by the modes of inheritance; CHED type 1 (CHED1) with autosomal dominant inheritance and CHED type 2 (CHED2) with autosomal recessive inheritance. Mutations in the sodium bicarbonate transporter-like solute carrier family 4 member 11 (SLC4A11) gene result CHED2.

METHODS

A 37 years old female was clinically diagnosed as CHED2. Peripheral blood from the patient and her family members was obtained under informed consents. Genomic DNA was extracted in their WBCs, and whole exons and exon-intron boundaries of the SLC4A11 gene were amplified using polymerase chain reaction. The amplified materials were analyzed by direct sequencing method.

RESULTS

The sequencing results of the SLC4A11 gene showed a novel homozygous mutation in exon 9 (c.1158C > A, p.C386*) in the proband with CHED2 phenotype. Her father and sister showing normal cornea were heterozygous carriers of the mutation. Her mother showing late onset Fuchs endothelial corneal dystrophy (FECD) also had the same mutation heterozygously.

DISCUSSION

We report a novel nonsense mutation of the SLC4A11 gene in the patient with CHED2. In addition, one of heterozygous carriers in this family showed features of late onset FECD. Close clinical ocular examination for the heterozygous carriers should be performed to detect late onset FECD.

Amyloid corneal deposition in corneal buttons of congenital hereditary endothelial dystrophy (CHED) - A clinical and histopathological case series

PURPOSE

To determine the frequency, pathology and clinical relevance of amyloid deposited in corneas of CHED.

METHODS

Clinical and histopathological case series.

RESULTS

Amyloid subepithelial deposition was found in 5 (6.6%) corneal buttons of 75 patients with histopathologically confirmed CHED diagnosis. Clinical findings included history of parental consanguinity, poor vision (ranging from counting fingers from one foot to 3/200), corneal edema, and central whitish subepithelial corneal nodules in all the five cases and positive family history in 4 of 5 cases. The patients underwent PKP at a mean age of 15 years (range 3-22 years). Histological findings included attenuated endothelium (6/6) thickened Descemet's membrane (6/6), stromal edema (2/6), and subepithelial amyloid deposits (6/6). All patients improved from vision point of view. To date, no recurrence of the amyloid has been seen in the grafts.

CONCLUSION

Considering the consanguinity, family history, early onset, and bilaterality, this study supports our hypothesis that the amyloid is primary in nature in our patients and indicates a new subtype of autosomal recessive CHED that require further chemical and genetic analysis. This subtype has the same prognosis for PKP as all CHED patients, if not better.