Stickler syndrome - lessons from a national cohort.

In 2011 NHS England commissioned a new national specialist MDT service for patients and families affected by Stickler syndrome. The Stickler syndromes form part of the spectrum of inherited vitreoretinopathies and are the most common cause of retinal detachment in childhood and the most common cause of familial retinal detachment. Now in its 10th year, the Stickler Highly Specialised Service (HSS) has assessed 1673 patients from 785 families. Using a combination of accurate phenotyping and molecular genetic analysis it is possible to identify the underlying genetic mutation in over 95% of cases including those with deep intronic mutations likely to be missed by conventional exome panel analysis and which require whole gene sequencing and supplementary functional analysis to confirm pathogenicity. The vast majority that presents to ophthalmologists will be from one of three autosomal dominant sub-groups with a high associated risk of retinal detachment but the diagnosis is often overlooked, especially in adults. In contrast to many other blinding retinal conditions, blindness through giant retinal tear detachment particularly in children is largely preventable provided these high-risk groups are identified and appropriate evidence-based prophylaxis offered. This article summarises ten selected briefcase histories from the national dataset with key learning points from each.

Stickler syndrome in children: a radiological review.

AIM: To review the radiological findings of the largest cohort to date of paediatric patients with Stickler syndrome, all with confirmed molecular genetic analysis and sub-typing. PATIENTS AND METHODS: It is understood that the National Health Service (NHS) commissioned service at Addenbrookes Hospital, Cambridge, UK has the largest cohort of Stickler syndrome patients in the paediatric age group worldwide with 240 registered children. Fifty-nine were assessed radiologically and for their genotypes. These radiographs were reviewed and 74 knee, 45 pelvic, and 47 spinal examinations were evaluated. RESULTS: Radiological features were noted in 45.9% of knee radiographs, 11.1% of pelvic radiographs, and 42.6% of spinal radiographs. The findings were reviewed in the light of each patient's specific genetic Stickler syndrome subtype. CONCLUSION: The prevalence of orthopaedic abnormalities overall in the present series is substantially below those published in previous smaller case series. This would support the more recent findings of an array of ocular only phenotypes of Stickler syndrome described in the literature.

Ophthalmic and molecular genetic findings in Kniest dysplasia.

PURPOSE: To study the variability of the ophthalmic phenotype in Kniest dysplasia. Kniest dysplasia is an inherited disorder associated with defects in type II collagen and characterised by short-trunked dwarfism, kyphoscoliosis, and enlarged joints with restricted mobility. Other features include marked hand arthropathy, cleft palate, hearing loss, and ocular abnormalities (myopia, abnormal vitreous, and high risk of developing retinal detachment). METHODS: Data from eight unrelated individuals with a clinical and molecular diagnosis of Kniest dysplasia are reported. Clinical assessment included an audiogram and ophthalmological examination in all but one patient who died in the immediate postnatal period. Sanger sequencing of the COL2A1 gene was performed. RESULTS: Six of the seven patients tested were high myopes with one patient being an emmetrope. Bilateral quandratic cataracts and subluxed lenses were noted in one subject. Variable but abnormal vitreous architecture was observed in all seven individuals tested. Six of the seven patients had significant hearing impairment and five of the seven patients exhibited clefting abnormalities. One patient had bilateral retinal detachments in his twenties. Six dominant disease-causing COL2A1 variants were detected. In three cases, testing of parental samples revealed that the disease-causing variant was not present in either parent. CONCLUSION: The ophthalmic features in Kniest dysplasia are very similar to those in other disorders of type II collagen such as Stickler syndrome. It is likely that different type II collagenopathies have a similar level of ocular morbidity and regular ophthalmologic examination is recommended. Kniest dysplasia is associated with heterozygous COL2A1 mutations that are frequently de novo.

Chronic wound and postamputation claudication pain in a diabetic patient.

Underlying ischaemic disease should be excluded in patients with delayed wound healing. Contrast angiography is a useful imaging method for assessing the specific cause of wound chronicity and may also be helpful in assessing the aetiology of unexplained pain symptoms. Angioplasty provides a practical alternative to more invasive techniques in addressing peripheral ischaemia. Our patient suffered claudication-type pain in his thigh and a non-healing stump wound following below-knee amputation. Magnetic resonance angiography confirmed the presence of arterial stenoses and an angioplasty was successfully performed to improve patency of the profunda femoris vessel. Following the operation, the claudication pain symptoms were significantly reduced and the stump wound went on to heal.

Topical steroids for chronic wounds displaying abnormal inflammation.

INTRODUCTION: Chronic, non-healing wounds are often characterised by an excessive, and detrimental, inflammatory response. We review our experience of using a combined topical steroid, antibiotic and antifungal preparation in the treatment of chronic wounds displaying abnormal and excessive inflammation. METHODS: A retrospective review was undertaken of all patients being treated with a topical preparation containing a steroid (clobetasone butyrate 0.05%), antibiotic and antifungal at a tertiary wound healing centre over a ten-year period. Patients were selected as the primary treating physician felt the wounds were displaying excessive inflammation. Healing rates were calculated for before and during this treatment period for each patient. Changes in symptom burden (pain, odour and exudate levels) following topical application were also calculated. RESULTS: Overall, 34 ulcers were identified from 25 individual patients (mean age: 65 years, range: 37-97 years) and 331 clinic visits were analysed, spanning a total time of 14,670 days (7,721 days 'before treatment' time, 6,949 days 'during treatment' time). Following treatment, 24 ulcers demonstrated faster rates of healing, 3 ulcers showed no significant change in healing rates and 7 were healing more slowly (p=0.0006). Treatment generally reduced the burden of pain and exudate, without affecting odour. CONCLUSIONS: In normal wound healing, inflammation represents a transient but essential phase of tissue repair. In selected cases, direct application of a steroid containing agent has been shown to improve healing rates, presumably by curtailing this phase. Further evaluation is required to establish the role of preparations containing topical steroids without antimicrobials in the management of chronic wounds.

Stickler syndrome, ocular-only variants and a key diagnostic role for the ophthalmologist.

The entity described by Gunnar Stickler, which included hereditary arthro-ophthalmopathy associated with retinal detachment, has recently been recognised to consist of a number of subgroups, which might now more correctly be referred to as the Stickler syndromes. They are the most common clinical manifestation of the type II/XI collagenopathies and are the most common cause of inherited rhegmatogenous retinal detachment. This review article is intended to provide the ophthalmologist with an update on current research, subgroups, and their diagnosis together with a brief overview of allied conditions to be considered in the clinical differential diagnosis. We highlight the recently identified subgroups with a high risk of retinal detachment but with minimal or absent systemic involvement--a particularly important group for the ophthalmologist to identify.

Clinicopathological changes at the vitreoretinal junction: posterior vitreous detachment.

Separation of the vitreous and posterior hyaloid membrane (PHM) or posterior vitreous detachment (PVD) typically occurs between the ages of 45 and 65 years in the general population, but may occur earlier in myopic or otherwise predisposed individuals. Age-related synergetic changes occurring within the cortical and central gel must be distinguished from the PHM, which envelopes it. This study reports on the correlation between 'true' PVD seen clinically by the physician using dynamic examination, high-power slit-lamp biomicroscopy, and oblique illumination with some of its histological, immunohistochemical, and ultrastructural features post-mortem. The presence of the Weiss ring does not necessarily indicate total clean separation of PHM, nor does its absence confirm that the PHM remains attached, since it may be destroyed during the process of separation. Immediately prior to PVD with the vitreous gel attached, the PHM must, by definition, form part of the inner limiting membrane. The detached PHM frequently exhibits basement membrane (BM) and its indigenous laminocytes stain focally for GFAP and type IV collagen. The PHM is distinct from and much thicker than the BM of Müller cells alone and the factors that initiate or limit separation of the PHM require greater study, particularly the role of laminocyte proliferation and migration.

The influence of pre-mRNA splicing on phenotypic modification in Stickler's syndrome and other type II collagenopathies.

PURPOSE: This paper will illustrate how variation in the processing of mutant pre-mRNA can affect the phenotypic outcome of inherited disorders of type II collagen. METHODS: Type 1 Stickler's syndrome is one of the different phenotypes resulting from mutations in COL2A1 (the type II collagenopathies). It is also the commonest, but often goes undiagnosed due to the variability of phenotypic features, which in some cases may consist of only abnormal vitreous development. Most cases of type 1 Stickler's syndrome are due to premature termination codons in the mRNA, resulting in haploinsufficiency. This leaves a conundrum as to why the disease is so variable. Using RT-PCR of illegitimate transcript and also minigenes, we have investigated how certain mutations can variably affect mRNA processing. RESULTS: Here, we demonstrate and discuss how apparently similar mutations can have a dramatically different effect on splicing of the pre-mRNA, switching transcripts from ones which would be degraded by nonsense-mediated decay into messages that will be translated into mutant proteins that can exert a dominant-negative effect and ultimately modify the resulting phenotype. CONCLUSION: Variability of Stickler's syndrome can, in part, be due to the variable effect that mutations have on the processing of the COL2A1 transcript.

Type 1 Stickler syndrome: a histological and ultrastructural study of an untreated globe.

AIMS: To present a histological and ultrastructural study of an untreated globe in a patient with genetically confirmed type 1 Stickler syndrome. METHODS: Histological and electron microscopic examinations were performed on the enucleated globe from the proband of a pedigree with type 1 Stickler syndrome. Linkage analysis was carried out using polymorphic markers flanking the COL2A1 gene and the mutation was identified by direct sequencing. RESULTS: The significant retinal abnormality was incarceration of vitreous collagen within glial strands on the inner surface of an atrophic and gliotic detached retina. The incarcerated collagenous layers contained glial cells and extended from the retina to form strands, some of which contributed to a retrolental membrane. Mutation screening detected a C to T mutation in exon 47 that inserted a premature termination codon into the reading frame of the mRNA. Sequence analysis of three of the four affected children confirmed that they were also heterozygous for the base change. The youngest child's DNA was not analysed. CONCLUSIONS: The study represents the first evidence of abnormal interactions between pathological vitreous collagen and the inner retina in a patient with type 1 Stickler syndrome with a confirmed mutation in the COL2A1 gene.

Clinical features and surgical management of retinal detachment secondary to round retinal holes.

AIMS: The majority of rhegmatogenous retinal detachments result from pathological posterior vitreous detachment (PVD) and secondary horseshoe or giant retinal tears. Retinal detachment without PVD is usually associated with either retinal dialysis or round retinal holes. This study characterises the features, surgical outcome, and incidence of bilateral involvement of detachment associated with round retinal holes. METHODS: In all, 110 retinal detachments from 96 consecutive patients with retinal detachment secondary to round retinal holes were studied. Analysis of patient age, sex, refraction, preoperative visual acuity, presented symptoms, position and extent of detachment, number and distribution of holes present, posterior hyaloid membrane status, surgical management, outcome of surgery, and postoperative visual acuity were studied. RESULTS: The mean age for patients was 34 years with a marked female preponderance (64%) and myopia (83%). The posterior hyaloid membrane remained attached in 95 eyes (86%). In all, 45% patients had bilateral pathology, of which 33% had 'mirror image' distribution. Detachments were predominantly shallow (93%) and slow in progression (17%). A total of 100 detachments were repaired with cryotherapy and scleral buckling, eight with cryotherapy alone, and one with laser retinopexy. In all, 99% detachments were successfully reattached with a single procedure. The mean follow-up period was 2 years. There were no instances of redetachment. CONCLUSIONS: Round hole detachments are slowly evolving detachments with attached vitreous gel in young, predominantly female myopes. Examination of the fellow eye should be mandatory as there is a high incidence of bilateral pathology. Scleral buckling procedures remained highly effective in this selected group of patients.

Hyperconvolution of the inner limiting membrane in vitreomaculopathies.

BACKGROUND: This study investigates the similarities and differences between epiretinal membranes in four clinically distinct types of vitreomaculopathy. We propose a hypothesis on the origin of the predominant cell type and its potential role in causing these conditions. METHODS: Epiretinal membranes (ERMs) surgically removed from a prospective, consecutive series of vitrectomies for macular pucker associated with an untreated peripheral horseshoe tear (MP), cellophane maculopathy (CM), stage 4 macular hole (MH) and vitreomacular traction syndrome (VMT) were examined by light microscopy and by immunocytochemistry (ICC) using antibodies marking type IV collagen, type II collagen, glial fibrillary acidic protein (GFAP), and low- and high-molecular-weight cytokeratin (MNF116). These specimens were compared with post-mortem control eyes with and without physiological posterior vitreous detachment (PVD). Light microscopy was carried out on 5-microm-thick sections cut from formalin-fixed, paraffin-embedded tissue blocks. Appropriate autoclave or enzyme pre-digestion steps were deployed to retrieve antigens for ICC. No patient had undergone previous vitreoretinal surgery or peripheral retinopexy. RESULTS: From a series of 38 patients, (13 CM, 8 MP, 16 MH and 1 VMT) a total of 20 specimens contained sufficient tissue for histology and immunocytochemistry. All specimens contained portions of inner limiting membrane (ILM) coated by GFAP-positive cells. Specimens from patients with MP and CM exhibited hyperconvolution of the ILM, which was not found in the specimens from patients with MH or VMT or in the control eyes. Hyperconvolution was associated with increased glial cell density, GFAP staining intensity and duplication of ILM basement membrane. Three cases of ERMs from the MP group contained, in addition, cytokeratin-positive cells. In the control group; post-mortem eyes with PVDs showed patchy staining of the posterior hyaloid membrane for GFAP and type 4 collagen. Post-mortem eyes with attached gel showed weak positivity of the ILM for type 4 collagen, and a monolayer of GFAP-positive cells lined the vitreous aspect of the ILM. CONCLUSIONS: These results indicate that glial cells are fundamentally important in the formation of ERMs found in this group of vitreomaculopathies. The hyperconvolution and duplication of the ILM in CM and MP were striking and distinctive features and suggest a mechanism by which these membranes exert tractional forces on the retina. Post-mortem control eyes contained a similar (but more dispersed) population of GFAP-positive cells in the region of the ILM, suggesting the primary aetiology for CM and MP may originate within the ILM. ERMs from MP cases may, in addition, contain cytokeratin-positive cells, of probable RPE origin.

Effects of mycorrhizal colonisation on Thymus polytrichus from heavy-metal-contaminated sites in northern England.

A study was performed to establish whether colonisation with arbuscular mycorrhizal (AM) fungi is beneficial to wild thyme [ Thymus polytrichus A. Kerner ex Borbás ssp. britannicus (Ronn.) Kerguelen (Lamiaceae)] growing in the heavy-metal-contaminated soils along the River South Tyne, United Kingdom. T. polytrichus plants of the same genotype were grown under controlled conditions with and without Zn contamination, and differences between AM-colonised and -uncolonised plants in mean shoot and root growth (dry weight) and Zn concentration were assessed. When grown in the heavy-metal-contaminated, low-P soil from one of the South Tyne sites, AM-colonised plants grew significantly larger than uncolonised plants; however, there was no significant difference in growth between AM and non-AM plants grown in an artificial substrate with a larger available P concentration, with or without Zn contamination. Mycorrhizal colonisation increased tissue Zn concentrations during the experiments. It is concluded that AM fungi are beneficial, if not essential, to T. polytrichus growing in the low-nutrient soils along the River South Tyne, because of their role in enhancing plant uptake of P (and possibly other nutrients). There was no evidence from this study that the fungi reduce plant uptake of heavy metals at these sites, but rather increase Zn uptake. However, the resulting tissue metal concentrations do not appear to be large enough to be detrimental to plant growth.

Relationships between soil heavy metal concentration and mycorrhizal colonisation in Thymus polytrichus in northern England.

A study was conducted to establish whether the wild thyme [ Thymus polytrichus A. Kerner ex Borbás ssp. britannicus (Ronn.) Kerguelen (Lamiaceae)] growing in the metal-contaminated soils along the River South Tyne, United Kingdom, is colonised by arbuscular mycorrhizal (AM) fungi, and whether the degree of colonisation increases (perhaps suggesting increasing mycorrhizal dependence) or decreases (indicating possible inhibition of AM growth) with increasing degree of soil contamination. Seasonal changes in AM colonisation were also assessed. The AM fungal communities colonising T. polytrichus were also investigated, using the polymerase chain reaction with restriction fragment length polymorphism and sequencing of fungal DNA to establish whether AM species richness varied between sites, and whether fungal ecotypes specific to sites with different amounts of metal contamination could be identified. All plants examined were heavily colonised by AM fungi, and mean percentage root length colonised did not increase significantly with increasing soil metal contamination. However, AM vesicle abundance (percentage of mycorrhizal root length containing vesicles) at the most contaminated site was significantly greater than at the other sites. No significant seasonal variation in degree of colonisation or vesicle abundance was found. Glomus was the predominant AM genus detected at all sites. The number of AM genotypes colonising T. polytrichus roots was similar at all sites but, although some were common to all sites, certain strains appeared to be specific to either the most- or the least-contaminated site. This variation in species may account for the difference in vesicle abundance between sites. The consistently heavy AM colonisation of T. polytrichus found suggests that these fungi are not inhibited by soil heavy metals at these sites, and that the host derives some benefit from its AM symbiont.

Apomixis in flowering plants: an overview.

Apomixis is a common feature of perennial plants, which occurs in ca. 60% of the British flora, but has been largely ignored by reproductive theoreticians. Successful individuals may cover huge areas, and live to great ages, favoured by 'symmetrical' selection. Apomixis is favoured by colonizing modes, for instance post-glacially. Despite its theoretical advantages, apomixis usually coexists with sexuality, suggesting 'hidden' disadvantages. Agamospermy (apomixis by seed) is relatively uncommon, but gains from the attributes of the seed. It pays agamospermy genes, which discourage recombination, to form co-adapted linkage groups, so that they become targets for disadvantageous recessive mutant accumulation. Consequently, agamospermy genes cannot succeed in diploids and agamosperms are hybrid and highly heterotic. Agamospermous endosperm may suffer from genomic imbalance, so that nutritious ovules, which can support embryos without endosperm, may be preadapted for agamospermy. When primary endosperm nucleus fertilization ('pseudogamy') continues as a requirement for many aposporous agamosperms, selfing sex becomes preadaptive and archesporial sex remains an option. Apomictic populations can be quite variable although apomictic families are much less variable than sexuals. Only in some diplosporous species does sex disappear completely, and in those species some release of variability may persist through somatic recombination. The search for an agamospermy gene suitable for genetic modification should target fertile sexuals with a single localized agamospermy (A) gene, which therefore lack a genetic load. The A gene should coexist alongside sexuality, so that it would be easy to select seedlings of sexual and asexual origins. Plants with sporophytic agamospermy provide all these attributes.

Vitreoretinopathy with phalangeal epiphyseal dysplasia, a type II collagenopathy resulting from a novel mutation in the C-propeptide region of the molecule.

A large family with dominantly inherited rhegmatogenous retinal detachment, premature arthropathy, and development of phalangeal epiphyseal dysplasia, resulting in brachydactyly was linked to COL2A1, the gene encoding proalpha1(II) collagen. Mutational analysis of the gene by exon sequencing identified a novel mutation in the C-propeptide region of the molecule. The glycine to aspartic acid change occurred in a region that is highly conserved in all fibrillar collagen molecules. The resulting phenotype does not fit easily into pre-existing subgroups of the type II collagenopathies, which includes spondyloepiphyseal dysplasia, and the Kniest, Strudwick, and Stickler dysplasias.

The effects of altitude, aspect, grazing and time on the proportion of cyanogenics in neighbouring populations of Trifolium repens L. (white clover).

The proportion of cyanogenic individuals of white clover amongst 200 individuals in each of 32 neighbouring populations in Northumberland, UK were recorded. Sites differed for four altitude zones, two aspects, and were either sheep pasture or ungrazed meadow. The proportion of cyanogenics showed a striking reduction with increasing altitude. Below 100 m, north-facing sites contained more cyanogenics than south-facing sites, but aspect did not affect higher sites. Grassland management had no effect on the proportion of cyanogenics. A 24-year study of one population showed highly significant changes in the proportion of cyanogenics over time, suggesting that a significant turnover of individuals occurs. In some cases, different size class cohorts varied for the proportion of cyanogenics within a year, and the same cohort varied between years. We conclude that environment at birth may determine the proportion of cyanogenics for that cohort, so that this proportion persists in that cohort as it matures. Comparisons of the proportion of cyanogenics with mean monthly averages for January minimum temperature, July maximum temperature and August rainfall showed a significant association only with mean January minima 2 1/2 years previously. We hypothesise that the 2 to 3-year cohort may predominate in this population. We suggest that winter cold and summer drought may both select against cyanogenics. Grazing by large herbivores does not favour cyanogenesis, but some invertebrate herbivory may do so. Most selection probably occurs at birth and will be greatest in populations with a high turnover.

Molecular genetics of rhegmatogenous retinal detachment.

Rhegmatogenous retinal detachment (RRD) most commonly occurs as a spontaneous event resulting from posterior vitreous detachment, typically between the ages of 40-70 yrs. It is also a feature in some inherited disorders, most commonly Stickler syndrome. The relationship between these inherited disorders and the spontaneous cases is unclear. Here in particular we review Stickler syndrome, and discuss the differential diagnosis of Stickler, Wagner and Marshall syndromes. Other rare inherited disorders associated with RRD are also briefly reviewed.

Clinical, histological and ultrastructural studies of the posterior hyaloid membrane.

AIMS: To investigate the histological, immunohistochemical and ultrastructural features of the posterior hyaloid membrane (PHM) in its naturally separated state in patients without previous surgery and slit-lamp documentation of antemortem posterior vitreous detachment (PVD). METHODS: A prospective study was commenced in 1992 to recruit patients with physiological PVD from an unselected group of general medical inpatients and ascertain the prevalence of PVD. Postmortem specimens subsequently available were studied to analyse the clinicopathological correlation and processed using standard techniques for histology, immunohistochemistry and electron microscopy. RESULTS: Eighty-five patients were examined with ages ranging from 68 to 98 yrs (mean 83.4 yrs). The posterior hyaloid membrane had clearly separated from the retina in 66% of eyes. Twenty-nine eyes from 15 patients were subsequently studied pathologically. The posterior hyaloid membrane exhibited a uniform cellular component, most densely populated around the Weiss' ring. The cells were characterised by oval or round nuclei, indistinct cytoplasm and were only seen within, or abutting, the weakly eosinophilic posterior hyaloid membrane. The posterior aspect of the posterior hyaloid membrane showed a convoluted appearance staining lightly with haematoxylin and eosin. The detached posterior hyaloid membrane exhibited focal positivity for GFAP and type IV collagen. Electron microscopy demonstrates both fibres and basement membrane associated with the cellular component including hemi-desmosome attachment plaques between the cells and basement membrane. CONCLUSIONS: This study illustrates some of the structural differences between the posterior hyaloid membrane and the cortical vitreous gel it envelopes and demonstrates the presence of cells intimately associated with the posterior hyaloid membrane in its naturally separated state. We propose the cellular population integral to the PHM to be designated as laminocytes in order to emphasise their type IV collagen/basement membrane association and planar array within the membrane which separates at posterior vitreous detachment.