Increased Subfoveal Choroidal Thickness and Retinal Structure Changes on Optical Coherence Tomography in Pediatric Alport Syndrome Patients

Genetic, Clinical, and Pathologic Backgrounds of Children With X-Linked Alport Syndrome in China: A Monocenter Study

Background. Characteristics of X-linked Alport syndrome (XLAS) in a cohort of Chinese children. Methods. This work is a retrospective study covering the clinical information, pathological data, and gene sequencing results of 32 cases with XLAS from 2011 to 2022. Results. Among these 32 patients, the youngest age of onset was 3 months. Renal biopsy was performed on 29 children. The lamellated glomerular basement membrane was observed in 19 children using electron microscopy (65.5%). Of the 26 samples tested, 73.1% were found to be negative for collagen-a5 under immunohistochemical staining, showing clinical significance. Next-generation sequencing (NGS) detected 27 pathogenic gene mutations. A total of 15.4% of patients carried de novo mutations. Conclusions. The boys with XLAS showed more typical pathological performance than the girls. Patients with severe mutation were more likely to have proteinuria and hearing impairment. Renal pathology combined with NSG is an important means of diagnosis of AS.

Ocular Manifestations and Potential Treatments of Alport Syndrome: A Systematic Review

Objectives. Alport syndrome (AS) is a severe, rare hereditary disorder that can lead to end-stage renal disease, auditory degeneration, and ocular abnormalities. Despite extensive research on AS in relation to auditory and renal disorders, more research is needed on the ocular presentations of AS. This systematic review aims to summarize the common ocular abnormalities in patients with AS and to explore the potential treatment options for these irregularities. Methods. The PubMed, MEDLINE, and EMBASE databases were systematically searched from January 1977 to April 2022. Only papers that were published in the English language and explored the ocular abnormalities in AS patients were selected. We manually searched reference lists of included papers for additional studies. Results. A total of 23 articles involving 195 patients were included in this review. The common ocular manifestations in AS patients are lenticonus, macular holes, fleck retinopathy, and thinning of the macula. Although published literature has described the use of cataract surgeries and vitrectomies as standard surgical techniques to alleviate ocular abnormalities in non-AS patients, it must be noted that surgical techniques have not been evaluated in a large research study as a solution for AS abnormalities. Another prospective treatment for AS is gene therapy through the reversion of causative COL4 variants to wild type or exon-skipping therapy for X-linked AS with COL4A5 truncating mutations. Gene therapy, however, remains unable to treat alterations that occur in the fetal and early development phase of the disease. Conclusions. The review found no definitive conclusions regarding the efficacy and safety of surgical techniques and gene therapy in AS patients. Recognition of ocular abnormalities through an ophthalmic examination with an optical coherence tomography (OCT) and slit-lamp examination is critical to the medical field, as ophthalmologists can aid nephrologists and other physicians in diagnosing AS. Early diagnosis and care can minimize the risk of detrimental ocular outcomes, such as blindness and retinal detachment.

Temporal retinal thinning might be an early diagnostic indicator in male pediatric X-linked Alport syndrome

AIM

To evaluate temporal retinal thinning changes in retinal layers using spectral-domain optical coherence tomography (SD-OCT) in pediatric X-linked Alport syndrome (XLAS) patients.

METHODS

A retrospective case-control study. SD-OCT scans of pediatric patients diagnosed with XLAS and age- and sex-matched healthy control participants were reviewed. Automated segmentation of SD-OCT scans was induced to analyze the retinal thickness (RT) of different layers. The temporal thinning index (TTI) was calculated for each layer and compared between the patients and the control group.

RESULTS

Forty-three pediatric XLAS patients and 60 healthy controls were included. Temporal retinal thinning was present in 33 patients (76.74%), while 28 patients (65.11%) had severe pathological temporal retinal thinning and 5 patients (11.63%) had moderate thinning. The temporal inner sector RT (P<0.0001), the temporal outer sector RT (P<0.0001), and the nasal outer sector RT (P=0.0211) were significantly thinner in the XLAS male patients. The TTI of the total retina was significantly higher in the XLAS group than in the control group (P<0.0001). The TTI of the inner retina layers (P<0.0001), ganglion cell layer (P<0.0001), inner plexiform layer (P<0.0001), inner nuclear layer (P<0.0001), and outer nuclear layer (P<0.0001) were significantly higher in the XLAS group. The central RT of the XLAS group was significantly thinner than that of the control group (P<0.0001).

CONCLUSION

Temporal retinal thinning appears early in XLAS patients, especially in male patients. The thinning is mainly caused by structural abnormalities of the inner retina. This suggests that temporal retinal thinning could be helpful for the early diagnosis and follow-up of XLAS with noninvasive SD-OCT examination.

Characterization of Choriocapillaris and Choroidal Abnormalities in Alport Syndrome

Purpose

To analyze the characteristics of the choriocapillaris and the choroid in patients with Alport syndrome (AS) and investigate their clinical and demographic associations.

Methods

Multicenter, cross-sectional study. Forty-two eyes with AS were consecutively enrolled. A cohort of 33 healthy eyes was included as controls. Demographics and medical history were collected for each participant. Each eye underwent 3 × 3 swept-source optical coherence tomography angiography (PLEX Elite 9000 2.0; Carl Zeiss Meditec, Dublin, CA, USA) and spectral-domain OCT (Spectralis HRA2; Heidelberg Engineering, Heidelberg, Germany). Choriocapillaris flow deficit (FD) number, mean FD size, total FD area, FD density, subfoveal choroidal thickness (CT), total CT, and choroidal vascularity index (CVI) were compared between AS and control eyes. Factors associated with the FD density and the CVI in AS were explored with multivariable linear mixed models.

Results

There was high intragroup variability in choriocapillaris and choroidal measurements in patients with AS. Choriocapillaris FD in patients with AS were more numerous compared to controls (P = 0.02). FD density in eyes with AS increased with older age (estimate = 0.31% for each year; 95% confidence interval [CI], 0.06−0.57; P = 0.02) and was higher in patients with a history of kidney transplant (estimate = 9.66% in case of positive history; 95% CI, 3.52−15.8; P = 0.006). The CVI was lower in eyes with dot maculopathy (estimate = −3.30% if present; 95% CI, −6.38 to −0.21; P = 0.04) and anterior lenticonus (estimate = −6.50% if present; 95% CI, −10.99 to −2.00; P = 0.006).

Conclusions

Patients with AS with kidney involvement requiring transplant may present with more severe choriocapillaris impairment. Lower choroidal vascularity was found in the presence of other ocular structural abnormalities.

Translational Relevance

An increased load of choriocapillaris flow deficits on optical coherence tomography angiography was found in patients with Alport syndrome who also had severe kidney disease requiring transplant.