The Stickler syndrome presenting as a dominantly inherited cleft palate and blindness

Dominant Stickler Syndrome

The Stickler syndromes are a group of genetic connective tissue disorders associated with an increased risk of rhegmatogenous retinal detachment, deafness, cleft palate, and premature arthritis. This review article focuses on the molecular genetics of the autosomal dominant forms of the disease. Pathogenic variants in COL2A1 causing Stickler syndrome usually result in haploinsufficiency of the protein, whereas pathogenic variants of type XI collagen more usually exert dominant negative effects. The severity of the disease phenotype is thus dependent on the location and nature of the mutation, as well as the normal developmental role of the respective protein.

Auditory dysfunction in type 2 Stickler Syndrome

PURPOSE

To present the extent and site of lesion of auditory dysfunction in a large cohort of individuals with type 2 Stickler Syndrome. Type 2 Stickler Syndrome results from a mutation in the gene coding for α-1 type XI pro-collagen, which has been identified in the human vitreous, cartilage and the cochlea of the mouse. The condition is characterised by classic ocular abnormalities, auditory dysfunction, osteoarthropathy and oro-facial dysplasia.

METHODS

This is a population study which used a combination of audiometric, tympanometric, and self-report measures on a series of 65 individuals (mean age 29.2 years, range 3-70, female 63.1%) with genetically confirmed type 2 Stickler Syndrome.

RESULTS

Hearing impairment was identified in at least one ear for 69% of individuals. Analysis against age-matched normative data showed that reduced hearing sensitivity was present across all test frequencies. Sensorineural hearing loss was most common (77% of ears), with conductive (3%), mixed (7%) and no hearing loss (13%), respectively. The proportion of hypermobile tympanic membranes (24%) was less than previously documented in type 1 Stickler Syndrome. When present, this appears to arise as a direct result of collagen abnormalities in the middle ear. Self-report measures of speech and spatial hearing in sound were comparable to a non-syndromic cohort with similar audiometric thresholds.

CONCLUSIONS

Auditory impairment in type 2 Stickler Syndrome is predominantly associated with cochlear hearing loss of varying severities across affected individuals. The impact on hearing thresholds can be seen across the frequency range, suggesting a contribution of defective collagen throughout the cochlea. Self-report questionnaires showed that difficulties understanding speech, and spatial information in sound (such as that used for localisation), were worse than a young, normal-hearing population but comparable to a non-syndromic cohort with similar audiometric thresholds. Therefore, it is likely that hearing loss in type 2 Stickler Syndrome arises in the auditory periphery, without significant central processing deficits.

Surgical management in a severe OSA patient diagnosed with Stickler syndrome

Stickler syndrome is a genetic disorder of connective tissue. One of the major symptoms associated with this disorder is an oro-facial malformation, which may cause a submucous cleft or a complete cleft of the hard palate. A 32-year-old man diagnosed with Stickler syndrome and a submucosal cleft palate (SMCP) visited our hospital with a chief complaint of excessive daytime sleepiness. The patient was diagnosed with severe obstructive sleep apnea (OSA), and administration of a polysomnography test revealed an apnea-hypopnea index (AHI) of 30.9 events/hour (h). Auto-titrating continuous positive airway pressure was initiated to control the OSA symptoms and subsequently the patient showed some improvement. However, due to continuous velopharyngeal insufficiency symptoms, intravelar veloplasty was performed. Three months after surgery, the AHI had decreased to 12.4 events/h. Recent studies have described a greater risk for OSA in individuals with cleft palate, than in the general population. The present case demonstrates surgical success in a patient with OSA and SMCP, suggesting that palatal surgery may be considered an optional surgical treatment for OSA patients with SMCP.

Clinical variability of Stickler syndrome: role of exon 2 of the collagen COL2A1 gene

Stickler syndrome (progressive arthro-ophthalmopathy) is a genetically heterogeneous disorder resulting from mutations in at least three collagen genes. The most common disease-causing gene is COL2A1, a 54-exon-containing gene coding for type II collagen. At least 17 different mutations causing Stickler syndrome have been reported in this gene. Phenotypically, it is also a variably expressed disorder in which most patients present with a wide range of eye and extraocular manifestations including auditory, skeletal, and orofacial manifestations. Some patients, however, present without clinically apparent systemic findings. This observation has led to difficulty distinguishing this Stickler phenotype from other hereditary vitreoretinal degenerations, such as Wagner syndrome and Snowflake vitreoretinal degeneration. In this regard, review of the literature indicates type II collagen exists in two forms resulting from alternative splicing of exon 2 of the COL2A1 gene. One form, designated as type IIB (short form), is preferentially expressed in adult cartilage tissue. The other form, designated as type IIA (long form), is preferentially expressed in the vitreous body of the eye. Because of this selective tissue expression, mutations in exon 2 of the COL2A1 gene have been hypothesized to produce this Stickler syndrome phenotype with minimal or absent extraocular findings. We review the evidence for families with exon 2 mutations of the collagen COL2A1 gene presenting in a distinct manner from families with mutations in the remaining 53 exons, as well as other hereditary vitreoretinal degenerations without significant systemic manifestations.

Genetics and hearing loss: a review of Stickler syndrome

Stickler syndrome is an autosomal dominant multisystem disease. The four most affected systems are craniofacial, skeletal, ocular, and auditory. The manifestations of Stickler syndrome vary considerably among affected individuals. Audiologists and speech-language pathologists should be familiar with the characteristics associated with Stickler syndrome to facilitate early identification and appropriate management.

Hereditary vitreopathy

Heterogeneity has long been recognised within the spectrum of inherited vitreo-retinal disease but the extent of the variation has been less easy to quantify. This has been compounded by the small size and numbers of pedigrees available for the study, and the phenotypic variation both within and between pedigrees. Formation abnormalities in the vitreous architecture have, in the past, been eclipsed by classifications based on general skeletal and morphological differences. Stickler syndrome is the commonest disorder within the spectrum of hereditary vitreous abnormalities and many of the recent published advances relate to this. Stickler syndrome has been subclassified on the basis of vitreo-retinal phenotype: type 1 families with a characteristic congenital vitreous anomaly show linkage without recombination to markers at the COL2A1 locus; type 2 families with different congenital vitreo-retinal phenotypes are not linked to COL2A1. A recent report identifies the COL11A2 mutation in a Dutch pedigree with systemic features of Stickler syndrome but without ocular involvement. Others have implicated COL11A1 in a type 2 Stickler syndrome pedigree with ocular abnormalities. Both COL11A1 and COL11A2 are expressed in cartilage, but on the basis of studies of bovine vitreous it is likely that only the alpha 1(XI) chain encoded by COL11A1 is present in vitreous. This would be consistent with the hypothesis that mutations in the genes encoding collagen XI can give rise to manifestations of Stickler syndrome, but of these, only mutations in COL11A1 will give the full syndrome including the vitreo-retinal features.

Variability of Stickler syndrome

Stickler syndrome is a dominantly inherited disorder characterized by ocular and nonocular manifestations. The phenotype of the affected patients is known to be variable. Our study of 3 families and a review of the literature show that the variability is mostly interfamilial while in each family less variability is present. In one family all the patients had high myopia and most developed a retinal detachment at a young age. In the second family the major symptoms were cleft palate and characteristic facial changes in presence of mild ocular changes. In the third family, all patients had a marfanoid habitus, high myopia, and mental retardation. Interfamilial variability coupled with intrafamilial similarities in clinical manifestation may indicate that the so-called Stickler syndrome represents in fact a phenotype and not a single genetic entity.

Marshall syndrome

We report on a mother and daughter with Marshall syndrome, with the Robin sequence present in the daughter. Results of our efforts to link this syndrome to a defect in type II collagen are reported. We compare and contrast Marshall syndrome with the Stickler syndrome, and propose that enough phenotypic overlap exists to suggest that they are probably allelic expressions of the same locus.

Distinctive cataract in the Stickler syndrome

We determined the clinical characteristics of cataract in 133 patients with the Stickler syndrome. Cataracts of various types or aphakia were found in 115 of 231 eyes (49.8%) studied. The most frequent and distinctive lesions, described as wedge and fleck cataracts, accounted for 40 of the 93 cataracts (43.0%) observed. These distinctive opacities may serve as a clinical marker for the Stickler syndrome and facilitate early diagnosis.

Otolaryngological manifestations of the Stickler syndrome

The Stickler syndrome is a dominantly inherited, connective tissue disorder associated with retinal detachments, joint and skeletal abnormalities, and characteristic facies. We wished to evaluate patients with this disorder to ascertain the frequency of otolaryngological manifestations. Fourteen patients, 4-17 years of age, were evaluated when admitted for retinal detachment. Findings included: midface hypoplasia in all patients; mandibular hypoplasia in 11 patients; palatal anomalies in 10 patients (frank cleft in 6, submucous cleft in two, highly arched palate in two); and hearing loss in 6 patients (mixed loss in 3, sensorineural loss in 3). Hearing loss appeared more commonly in the higher frequencies; no apparent correlation was found between the presence of hearing loss and orofacial anomalies. Our experience suggests that the Stickler syndrome is not rare. Craniofacial dysmorphic features and otologic findings are sufficiently frequent to warrant otolaryngological evaluation.

Wagner's vitreoretinal degeneration with generalized epiphyseal dysplasia

Wagner's vitreoretinal degeneration, midline facial defects and a moderate generalized epiphyseal dysplasia defined radiologically were encountered in a boy and his father. The familial nature of the condition and its autosomal dominant inheritance are described. Suggestions are made that patients said to have Wagner's disease differ in no way radiologically from cases diagnosed as having Stickler's syndrome.

The Weissenbacher-Zweymüller syndrome: possible neonatal expression of the Stickler syndrome

The Robin anomaly is a recognized presenting manifestation of the Stickler syndrome, an autosomal dominantly inherited disorder originally termed "hereditary progressive arthroophthalmopathy." We report an infant with the Robin anomaly, myopia and dumbbell-shaped femora and humeri in a family with the Stickler syndrome. This observation suggests that the Weissenbacher-Zweymüller syndrome is in fact a variant of the Stickler syndrome.

The Wagner-Stickler syndrome complex

The Wagner's vitreoretinal degeneration is a condition characterized by myopia, cataract, optically empty vitreous cavity and retinal breaks leading to retinal detachments with poor surgical prognosis. Several extraocular manifestations were reported to be associated with these eye findings and various syndromes were delineated describing sensorineural deafness, orofacial anomalies and skeletal dysplasias. There is enough evidence to suggest that this condition results from a phenotypic variability of genic origin, transmitted as an irregular autosomal dominant trait. In the absence of knowledge about the primary gene defect, the problems in nosology emphasize the difficulty in distinguishing genetic heterogeneity from variable gene expression. In view of the great deal of similarity between all these syndromes with vitreoretinal degeneration it is suggested that all these entities represent the extremes of the same disease spectrum forming parts of a continuum.

Hereditary vitreoretinal degeneration, cleft lip and palate, deafness, and skeletal dysplasia

Two brothers and their mother had vitreoretinal degeneration associated with cleft palate, a peculiar physiognomy, skeletal anomalies, and sensorineural deafness. The pattern of inheritance in this family suggested autosomal dominant transmission.

Retinal detachment in median cleft-face syndrome

A 7-year-old boy had an unusual association of median cleft-face syndrome, a characteristic physiognomy, unilateral retinal dysplasia, and bilateral retinal detachment. Despite surgical treatment to both eyes he became blind. The hereditary pattern operating in this complex disorder was found to be consistent with an autosomal dominant trait.