Ophtalmologic diagnosis of lymphedema-distichiasis syndrome through the FOXC2 mutation

Lymphedema distichiasis syndrome is one of the most frequent phenotypes of primary lymphedema, even so, its prevalence is still low. This syndrome courses with the appearance of abnormal eyelashes and distichiasis during childhood or puberty. This can cause a notable discomfort on our patients, especially at such an early age. The clinic evaluation of this signs must make us have in mind this group of syndromes, because in the case of lymphedema distichiasis syndrome, we can certainly diagnose it with the genetic analysis of the FOXC2 gen on patient's serum. With this we could prevent, diagnose and treat the ophthalmologic syndrome alongside the rest of systemic symptoms of this syndrome in a more effective way, giving our patients a higher quality of life.

Genomic analysis and prediction of genomic values for distichiasis in Staffordshire bull terriers

BACKGROUND

Distichiasis is a condition characterized by aberrant hairs along the eyelid margins. The symptoms are usually mild but can lead to ulcerations and lesions of the cornea in severe cases. It is the most frequently noted ocular disorder in Norwegian Staffordshire bull terriers (SBT), with a prevalence above 18% in the adult population. A complex inheritance is assumed, but there is sparse knowledge about the genetic background of distichiasis in dogs. We have performed a genome-wide association study of distichiasis in SBT and used genomic data in an attempt to predict genomic values for the disorder.

RESULTS

We identified four genetic regions on CFA1, CFA18, CFA32 and CFA34 using a mixed linear model association analysis and a Bayesian mixed model analysis. Genomic values were predicted using GBLUP and a Bayesian approach, BayesR. The genomic prediction showed that the 1/4 of dogs with predicted values most likely to acquire distichiasis had a 3.9 -4.0 times higher risk of developing distichiasis compared to the quarter (1/4) of dogs least likely to acquire the disease. There was no significant difference between the two methods used.

CONCLUSION

Four genomic regions associated with distichiasis were discovered in the association analysis, suggesting that distichiasis in SBT is a complex trait involving numerous loci. The four associated regions need to be confirmed in an independent sample. We also used all 95 K SNPs for genomic prediction and showed that genomic prediction can be a helpful tool in selective breeding schemes at breed level aiming at reducing the prevalence of distichiasis in SBTs in the future, even if the predictive value of single dogs may be low.

[Palpebral marginoplasty in the management of distichiasis: About 104 eyes]

Distichiasis is an anomaly of the of the eyelid margin characterized by the presence of a second row of eyelashes arising from the posterior lamella. It is a rare condition whose severity is related to corneal complications. There are two forms: congenital and acquired, the latter of which is the most frequent in our population, resulting mainly from chronic inflammation. There are several treatment modalities, the choice of which is up to the practitioner depending on the means at his or her disposal and the risk-benefit ratio. We report a series of 104 eyes (90 patients) undergoing surgery for distichiasis using the marginoplasty technique with labial mucosal autograft, collected between January 2000 and September 2021. The main indication was any distichiasis with more than seven lashes per eyelid. The mean age of the patients was 65.5 years. With a mean follow-up of over 24 months, a reduction in functional signs was noted in over 95% of cases. The success rate after marginoplasty with labial mucosal autograft alone was 82.7%. The recurrence rate was 17.3%, which patients underwent additional treatment by argon laser photoablation with very good final results (96% final success rate). Marginoplasty with labial mucosal autograft represents a technique of choice in distichiasis threatening the cornea, particularly in cases of distichiasis with a significant number of eyelashes to be treated.

Heritability of distichiasis in Havanese dogs in Norway

BACKGROUND

Distichiasis is a presumed inherited eyelid disease, characterized by misplaced eyelashes. The effect on eye health and animal welfare varies between individuals; most mild cases show no clinical signs, but some affected animals develop painful corneal disease. In this study, we investigated the prevalence and heritability of distichiasis in the Norwegian population of Havanese dogs.

RESULTS

A total of 1156 Havanese were included in the study. Out of these, 168 were affected with distichiasis, making the prevalence in our sample 14.5% (95% CI 12.5-16.6%). There was no sex predisposition. Most affected individuals were graded "mildly affected". The estimates generally showed high heritabilities, which varied between 0.276 (linear model) and 0.720 (Bayesian threshold model). The linear estimates, after conversion to the underlying scale (h2l = 0.664-0.674), corresponds well to the results of the Bayesian models.

CONCLUSIONS

The estimated heritability of distichiasis in Havanese is high and the prevalence is moderate. The high heritability indicate that a significant selection response could be obtained by simple mass selection. To secure good animal welfare, it's important to control the number of affected individuals and especially the severely affected.

Whole genome sequencing identified a 16 kilobase deletion on ECA13 associated with distichiasis in Friesian horses

BACKGROUND

Distichiasis, an ocular disorder in which aberrant cilia (eyelashes) grow from the opening of the Meibomian glands of the eyelid, has been reported in Friesian horses. These misplaced cilia can cause discomfort, chronic keratitis, and corneal ulceration, potentially impacting vision due to corneal fibrosis, or, if secondary infection occurs, may lead to loss of the eye. Friesian horses represent the vast majority of reported cases of equine distichiasis, and as the breed is known to be affected with inherited monogenic disorders, this condition was hypothesized to be a simply inherited Mendelian trait.

RESULTS

A genome wide association study (GWAS) was performed using the Axiom 670 k Equine Genotyping array (MNEc670k) utilizing 14 cases and 38 controls phenotyped for distichiasis. An additive single locus mixed linear model (EMMAX) approach identified a 1.83 Mb locus on ECA5 and a 1.34 Mb locus on ECA13 that reached genome-wide significance (pcorrected = 0.016 and 0.032, respectively). Only the locus on ECA13 withstood replication testing (p = 1.6 × 10- 5, cases: n = 5 and controls: n = 37). A 371 kb run of homozygosity (ROH) on ECA13 was found in 13 of the 14 cases, providing evidence for a recessive mode of inheritance. Haplotype analysis (hapQTL) narrowed the region of association on ECA13 to 163 kb. Whole-genome sequencing data from 3 cases and 2 controls identified a 16 kb deletion within the ECA13 associated haplotype (ECA13:g.178714_195130del). Functional annotation data supports a tissue-specific regulatory role of this locus. This deletion was associated with distichiasis, as 18 of the 19 cases were homozygous (p = 4.8 × 10- 13). Genotyping the deletion in 955 horses from 54 different breeds identified the deletion in only 11 non-Friesians, all of which were carriers, suggesting that this could be causal for this Friesian disorder.

CONCLUSIONS

This study identified a 16 kb deletion on ECA13 in an intergenic region that was associated with distichiasis in Friesian horses. Further functional analysis in relevant tissues from cases and controls will help to clarify the precise role of this deletion in normal and abnormal eyelash development and investigate the hypothesis of incomplete penetrance.

A new perspective in oculoplastic surgical management of symptomatic distichiasis in lymphedema-distichiasis syndrome

Lymphedema-distichiasis syndrome (LDS) is an autosomal dominant condition associated with FOXC2 mutations. Patients with distichiasis are mostly symptomatic, and efforts to deal with their ocular complaints comprise of electrolysis, cryotherapy and a variety of surgical techniques. We describe an enhanced surgical technique for a case of symptomatic distichiasis of the right eye with scarred, irregular eyelid margins secondary to initial cryotherapy, whereby the distorted tarsus was excised to remove the aberrant hair follicles, the levator palpebrae superioris was released to extend the upper lid and prevent lagophthalmos and a mucous membrane graft was used to cover the exposed portion of the tarsal plate. At 14 months follow up, the lid cosmesis and position remained satisfactory, with no infection or rejection of the mucous membrane graft. Therefore, this surgical technique provides a sound option for symptomatic distichiasis, where cryotherapy can cause lid irregularity and keratinization.

Modified treatment of distichiasis with direct tarsal strip excision without mucosal graft

PURPOSE

To describe a new modified technique of direct tarsal excision for treatment of distichiasis.

METHODS

Retrospective review of consecutive patients who underwent direct tarsal excision without grafting to treat distichiasis between December 2007 and November 2015. Gender, number of eyelids treated, follow-up time, and surgical outcome were recorded. The technique involved dividing the anterior and posterior lamella and excising a two mm tarsoconjunctival strip including the abnormal lash follicles, without suturing or mucosal graft.

RESULTS

Seventeen eyelids of 12 patients (Fourteen upper eyelids and 3 lower eyelids) were studied. Sixteen eyelids had acquired distichiasis and one eyelid had congenital distichiasis. Mean age was 64.8 (SD 22.0; range, 25-86 years) Mean postoperative follow-up time was 53 months (SD = 31, range 8 - 104 months). During this period, no recurrence was documented. There were no complications.

CONCLUSIONS

Direct tarsal excision without a graft is a safe, quick, and effective method for the treatment of distichiasis.

Congenital distichiasis: Histopathological report of 3 cases

Distichiasis is a condition clinically presenting as partial or complete accessory row of lashes that emerges from the meibomian glands orifices. It can be an acquired or congenital with an autosomal dominant inheritance. The histopathological features are not well described in the ophthalmic literature, however they include abnormal pilosebaceous units within the posterior lamella of the eyelid and perifollicular chronic inflammatory cell infiltration. In this report, we describe the histopathological findings of three congenital distichiasis cases treated at King Khaled Eye Specialist Hospital (KKESH), Riyadh, Saudi Arabia with discussion on the pathogenesis of such a condition and the differentiating features from ectopic cilia.

Prevalence and heritability of distichiasis in the English Cocker spaniel

BACKGROUND

Canine distichiasis is a well-known cause of ocular irritation and excessive lacrimation (secretion of tears) in the dog. The term distichiasis originates from the Greek words di and stichos meaning two and rows, respectively, and as the name implies, the condition is characterized by an additional row of cilia, which erupts on the eyelid margin. Many purebred dogs are known to be predisposed to the condition, with many affected individuals within the populations. Even though the problem is widespread, the exact mode of inheritance and the heredity has not been studied extensively. However, some degree of genetic influence has been assumed, due to the high incidences within specific breeds. In the present study we have examined a cohort of English Cocker spaniels in Denmark to determine the prevalence and heritability of the disease.

RESULTS

Data from English Cocker spaniels with an ECVO eye examination registered between 2004-2013 were included in the study. The number of dogs examined during this period was 799, and the prevalence of distichiasis within this cohort was estimated at 49.31 % with a gender predisposition that females are more likely to get distichiasis than males. The correlation between the distichiasis status of the parents and their offspring revealed a significant association between the breeding combination of the parents and the occurrence of distichiasis in the offspring (p <0.0001). A relative risk (RR) ranging from 1.3 to 1.8 demonstrates that offspring of two affected parents are more likely to be affected than offspring descending from either one or two unaffected parents. The heritability was estimated to be moderate to high, i.e., 0.22 to 0.51.

CONCLUSIONS

The prevalence of distichiasis in English Cocker spaniels from Denmark, examined in 2004-2013 was shown to be extremely high. The relative risk of developing the disease was 1.3 and 1.8 for offspring of one or two affected parents respectively. This together with the moderate to high heritability of the condition indicates that selective breeding could be used to reduce the incidence of distichiasis.

Utility of meibography in the evaluation of meibomian glands morphology in normal and diseased eyelids

PURPOSE

To study the utility of meibography for the morphology of meibomian glands in normal eyelids and in various eyelid diseases.

DESIGN

A cross-sectional study.

METHODS

A newly designed transilluminator, fitting both the upper along with lower eyelids, and an infrared camera were used to obtain video clips of the meibomian glands for 60 asymptomatic subjects with normal eyelid margin. Parameters studied included, ocular surface, Schirmer test, and tear breakup time (TBUT). The meibomian glands of patients with meibomian glands' abnormality secondary to infectious, inflammatory, malignant, congenital, or post-radiation therapy disease related etiologies were compared with normal patients. Still pictures were extracted from the video clips to evaluate the meibomian glands for gland dropout and gross morphological changes.

RESULTS

In normal subjects, meibomian glands appeared to be thinner and longer in the upper eye lids than in the lower eye lids. Gland dropout occured with increased age, more in the lower eye lid and in females. Excessive gland drop out (> 75%) was seen in patients with history of trachoma, Stevens Johnson syndrome, severe blepharitis, and post-radiation for orbital tumors. Variable gland drop out was noticed in patients with floppy eyelid syndrome, and blepharitis. In patients with congenital distichiasis, partial or complete gland drop out at the part of the eyelid margins affected by distichiasis was noticed.

CONCLUSIONS

The newly designed transilluminator permitted the examination of both upper and lower eye lid meibomian glands with minimal discomfort. Evaluating the anatomical changes involving meibomian glands with meibography may help increase our understanding of the meibomian gland-related diseases, monitor the effects of treatment, and provide helpful information for patient education.