A report on 10 new patients with heterozygous mutations in theCOL11A1 gene and a review of genotype–phenotype correlations in type XI collagenopathies

Microphthalmia and congenital cataract in two patients with Stickler syndrome type II: a case report

BACKGROUND

Stickler syndrome (STL) is a collagenopathy caused by pathogenic variants in collagen-coding genes, mainly COL2A1 or COL11A1 associated with Stickler syndrome type 1 (STL1) or type 2 (STL2), respectively. Affected individuals manifest ocular, auditory, articular, and craniofacial findings in varying degrees. Previous literature and case reports describe high variability in clinical findings for patients with STL. With this case report, we broaden the clinical spectrum of the phenotype.

MATERIALS AND METHODS

Case report on two members of a family (mother and son) including clinical examination and genetic testing using targeted trio whole exome sequencing (trio-WES).

RESULTS

A boy and his mother presented with microphthalmia, congenital cataract, ptosis, and moderate-to-severe sensorineural hearing loss. Trio-WES found a novel heterozygote missense variant, c.4526A>G; p(Gln1509Arg) in COL11A1 in both affected individuals.

CONCLUSIONS

We report a previously undescribed phenotype associated with a COL11A1-variant in a mother and son, expanding the spectrum for phenotype-genotype correlation in STL2, presenting with microphthalmia, congenital cataract, and ptosis not normally associated with Stickler syndrome.

[Features of genetic mutations in children with high myopia combined with peripheral retinal degenerations]

Degenerative changes in the peripheral regions of the ocular fundus allow a closer look at both the role of collagen genes and their mutations in children with high myopia.

PURPOSE

The study investigates the features of genetic mutations in children with high myopia combined with peripheral retinal degenerations.

MATERIAL AND METHODS

Study group was formed from the database of genetic studies of the Scientific and Clinical Center OOO Oftalmic, which consists of 4362 patients referred for medical genetic counseling and molecular genetic testing from 2016 to 2021. Selection criteria were: male and female patients, aged 5-18 years old, who had the following clinical signs: high myopia (>6.00 D) and the presence of peripheral retinal degenerations (PRD). The study considered both isolated cases of ophthalmic pathology, as well as its syndromic forms. The final selection included 40 children. All patients had consulted with a geneticist. Whole-exome sequencing (WES), next generation sequencing (NGS), and single gene sequencing were conducted by taking 5 mL of peripheral venous blood and extracting deoxyribonucleic acid (DNA).

RESULTS

In patients with isolated cases of ophthalmic pathology (peripheral retinal degenerations and high myopia) with a confirmed genetic diagnosis, mutations in the COL2A1 gene were detected in 77.4% of cases, and in the COL11A1 gene - in 22.6% of cases. In Stickler syndrome with a confirmed genetic diagnosis, mutations in the COL2A1 gene were detected in 33.3% of cases. In Marshall syndrome, the mutation in the COL11A1 gene was detected in 11.1% of cases. In children with Ehlers-Danlos, Knobloch type 1, Cohen, Marfan, Wagner syndromes mutations in the genes COL5A1, COL18A1, VPS13B, FBN1, VCAN were detected in 55.6% of cases. In 33.3% of cases of Knobloch type 1, Cohen, Wagner syndromes the mutation is found in both copies of the gene (i.e., in both chromosomes), which leads to the development of peripheral retinal degenerations with high myopia.

CONCLUSION

The results of the conducted molecular genetic testing expand our understanding of the mutation spectrum in the genes of children with both isolated cases of ophthalmic pathology, as well as syndromic pathology.

Multiocular defect in the Old English Sheepdog: A canine form of Stickler syndrome type II associated with a missense variant in the collagen-type gene COL11A1

Multiocular defect has been described in different canine breeds, including the Old English Sheepdog. Affected dogs typically present with multiple and various ocular abnormalities. We carried out whole genome sequencing on an Old English Sheepdog that had been diagnosed with hereditary cataracts at the age of five and then referred to a board-certified veterinary ophthalmologist due to owner-reported visual deterioration. An ophthalmic assessment revealed that there was bilateral vitreal degeneration, macrophthalmos, and spherophakia in addition to cataracts. Follow-up consultations revealed cataract progression, retinal detachment, uveitis and secondary glaucoma. Whole genome sequence filtered variants private to the case, shared with another Old English Sheepdog genome and predicted to be deleterious were genotyped in an initial cohort of six Old English Sheepdogs (three affected by multiocular defect and three control dogs without evidence of inherited eye disease). Only one of the twenty-two variants segregated correctly with multiocular defect. The variant is a single nucleotide substitution, located in the collagen-type gene COL11A1, c.1775T>C, that causes an amino acid change, p.Phe1592Ser. Genotyping of an additional 14 Old English Sheepdogs affected by multiocular defect revealed a dominant mode of inheritance with four cases heterozygous for the variant. Further genotyping of hereditary cataract-affected Old English Sheepdogs revealed segregation of the variant in eight out of nine dogs. In humans, variants in the COL11A1 gene are associated with Stickler syndrome type II, also dominantly inherited.

The genetics and disease mechanisms of rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) is a sight threatening condition that warrants immediate surgical intervention. To date, 29 genes have been associated with monogenic disorders involving RRD. In addition, RRD can occur as a multifactorial disease through a combined effect of multiple genetic variants and non-genetic risk factors. In this review, we provide a comprehensive overview of the spectrum of hereditary disorders involving RRD. We discuss genotype-phenotype correlations of these monogenic disorders, and describe genetic variants associated with RRD through multifactorial inheritance. Furthermore, we evaluate our current understanding of the molecular disease mechanisms of RRD-associated genetic variants on collagen proteins, proteoglycan versican, and the TGF-β pathway. Finally, we review the role of genetics in patient management and prevention of RRD. We provide recommendations for genetic testing and prophylaxis of at-risk patients, and hypothesize on novel therapeutic approaches beyond surgical intervention.

Characteristics of a Three-Generation Family with Stickler Syndrome Type I Carrying Two Different COL2A1 Mutations

Stickler Syndrome is typically characterized by ophthalmic manifestations including vitreous degeneration and axial lengthening that predispose to retinal detachment. Systemic findings consist of micrognathia, cleft palate, sensorineural hearing loss, and joint abnormalities. COL2A1 mutations are the most common, however, there is a lack of genotype-phenotype correlations. Retrospective, single-center case series of a three-generation family. Clinical features, surgical requirements, systemic manifestations, and genetic evaluations were collected. Eight individuals clinically displayed Stickler Syndrome, seven of whom had genetic confirmation, and two different COL2A1 mutations (c.3641delC and c.3853G>T) were identified. Both mutations affect exon 51, but display distinct phenotypes. The c.3641delC frameshift mutation resulted in high myopia and associated vitreous and retinal findings. Individuals with the c.3853G>T missense mutation exhibited joint abnormalities, but mild ocular manifestations. One individual in the third generation was biallelic heterozygous for both COL2A1 mutations and showed ocular and joint findings in addition to autism and severe developmental delay. These COL2A1 mutations exhibited distinct eye vs. joint manifestations. The molecular basis for these phenotypic differences remains unknown and demonstrates the need for deep phenotyping in patients with Stickler syndrome to correlate COL2A1 gene function and expression with ocular and systemic findings.

Hearing Loss in Stickler Syndrome: An Update

Stickler syndrome is a connective tissue disorder characterized by ocular, skeletal, orofacial and auditory manifestations. Its main symptoms are high myopia, retinal detachment, joint hypermobility, early osteoarthritis, cleft palate, midfacial hypoplasia, micrognathia and hearing loss. Large phenotypical variability is apparent and partly explained by the underlying genetic heterogeneity, including collagen genes (COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, COL9A3) and non-collagen genes (BMP4, LRP2, LOXL3). The most frequent type of Stickler syndrome (COL2A1) is characterized by a rather mild high-frequency sensorineural hearing loss in about half of the patients. COL11A1- and COL11A2-related Stickler syndrome results in more frequent hearing loss, being moderate and involving all frequencies. Hearing loss in the rarer types of Stickler syndrome depends on the gene expression in the cochlea, with moderate to severe downsloping hearing loss for Stickler syndrome caused by biallelic type IX collagen gene mutations and none or mild hearing loss for the non-collagen genes. Inherent to the orofacial manifestations, middle ear problems and temporary conductive hearing loss, especially at young age, are also prevalent. Consequently, hearing loss should be actively sought for and adequately treated in Stickler syndrome patients given its high prevalence and the concomitant visual impairment in most patients.

A recurrent variant in LIM2 causes an isolated congenital sutural/lamellar cataract in a Japanese family

Background

Genetically determined cataract is both clinically and molecularly highly heterogeneous. Here, we have identified a heterozygous variant in the lens integral membrane protein LIM2, the second most abundant protein in the lens, responsible for congenital sutural/lamellar cataract in a three-generation Japanese family.

Methods

Whole exome sequencing (WES) was undertaken in one affected and one unaffected individual from a family with autosomal dominant congenital cataract to establish the underlying genetic basis.

Results

A recurrent missense variant LIM2: c.388C>T; p.R130C was identified and found to co-segregate with disease. In addition, one variant COL11A1:c.3788C>T of unknown significance (VUS) was also identified.

Conclusions

We report a variant in LIM2 causing an isolated autosomal-dominant congenital sutural/lamellar cataract in a Japanese family. This is the first report of a LIM2 variant in the Japanese population. Hence, we expand the mutation spectrum of LIM2 variants in different ethnic groups.

Tendon and Ligament Genetics: How Do They Contribute to Disease and Injury? A Narrative Review

A significant proportion of patients requiring musculoskeletal management present with tendon and ligament pathology. Our understanding of the intrinsic and extrinsic mechanisms that lead to such disabilities is increasing. However, the complexity underpinning these interactive multifactorial elements is still not fully characterised. Evidence highlighting the genetic components, either reducing or increasing susceptibility to injury, is increasing. This review examines the present understanding of the role genetic variations contribute to tendon and ligament injury risk. It examines the different elements of tendon and ligament structure and considers our knowledge of genetic influence on form, function, ability to withstand load, and undertake repair or regeneration. The role of epigenetic factors in modifying gene expression in these structures is also explored. It considers the challenges to interpreting present knowledge, the requirements, and likely pathways for future research, and whether such information has reached the point of clinical utility.

Mutation survey in Taiwanese patients with Stickler syndrome

PURPOSE

The purpose of this study was to identify gene mutation and phenotype correlations in a cohort of Taiwanese patients with Stickler syndrome.

MATERIALS AND METHODS

Patients clinically diagnosed with Stickler syndrome or suspected Stickler syndrome were enrolled. DNA was extracted from venous blood samples. For the targeted next-generation sequencing (NGS) approach, specific primers were designed for all COL2A1, COL11A1, COL11A2, COL9A1, and COL9A2 exons and flanking intron sequences.

RESULTS

Twenty-three patients from 12 families were enrolled in this study. The myopia power in these 23 cases (35 eyes) ranged from -4.625 to -25.625 D, with a median of -10.00 D. Four patients had retinal detachment. Fourteen patients had a cleft palate. These 23 patients and 13 healthy controls were enrolled in the NGS study. Three families had significant single nucleotide variants (SNVs) in COL2A1. The mutation rates in this survey were 25% (3/12 families) and 35% (8/23 cases). The SNV of family #1, located at exon 27, c.1753G >T, p. Gly585Val, was novel and has not yet been reported in the ClinVar database. Families #10 and #11 had the same SNV, located in exon 33, c.2101C >T, p. Arg701X. Both variants were classified as likely pathogenic according to the American College of Medical Genetics and Genomics guidelines.

CONCLUSION

Genetic mutations in COL2A1 were found in 25% of Taiwanese families with Stickler syndrome. One novel variant was identified using NGS, which expanded the COL2A1 mutation spectrum. Molecular genetic analysis is helpful to confirm the clinical diagnosis of patients with suspected Stickler syndrome.

Identification of three novel homozygous variants in COL9A3 causing autosomal recessive Stickler syndrome

BACKGROUND

Stickler syndrome (STL) is a rare, clinically and molecularly heterogeneous connective tissue disorder. Pathogenic variants occurring in a variety of genes cause STL, mainly inherited in an autosomal dominant fashion. Autosomal recessive STL is ultra-rare with only four families with biallelic COL9A3 variants reported to date.

RESULTS

Here, we report three unrelated families clinically diagnosed with STL carrying different novel biallelic loss of function variants in COL9A3. Further, we have collected COL9A3 genotype-phenotype associations from the literature.

CONCLUSION

Our report substantially expands the molecular genetics and clinical basis of autosomal recessive STL and provides an overview about allelic COL9A3 disorders.

Non-Syndromic Sensorineural Prelingual and Postlingual Hearing Loss due to COL11A1 Gene Mutation

This paper aims to present a third world case of Non-Syndromic sensorineural hearing loss (NSHL) due to a novel missense variant in COL11A1 gene, defined as DFNA37 non-syndromic hearing loss. The clinical features of a 6-year-old boy affected by a bilateral moderate to severe down-sloping sensorineural hearing loss are presented, as well as the genetic analysis, the latter identifying a heterozygous missense variation in the COL11A1 gene. In addition, in families with autosomal dominant transmission, COL11A1 gene should be considered in the genetic workup of the NSHL with prelingual onset.

Novel Mutation in the COL11A1 Gene Causing Marshall-Stickler Syndrome in Three Generations of a Bulgarian Family

Here we report the first familial case spread through at least three generations, genetically verified cases of Marshall-Stickler syndrome in Bulgaria. The proband, a 2-year-old girl, has craniofacial dysplasia, ocular hypertelorism, small saddle nose with a flat bridge and midface hypoplasia. The pedigree of the proband’s family showed that her father has the same clinical manifestations of the disease. In addition, her father presented with a tall, thin stature and mild hearing loss, manifested with aging. The same dysmorphological symptoms were presented by the paternal grandfather. Both patients, the 2-year-old girl and her father, have been diagnosed to carry Marshall-Stickler syndrome. The COL2A1 gene tested negative in the family. Based on the higher percentage of mutations in the COL2A1 gene, we analyzed this gene as the first target in the family. The COL2A1 gene tested negative, and we sequenced the gene further. A novel splice site mutation c.3474+1G>A was found in intron 44. This variant is related to the clinical presentation in the patient and her father. The c.3474+1G>A mutation results in altered splicing affects at the donor splice site of intron 44, which most probably gives a nonfunctional protein. The variant affects the major triple-helical domain that represents a mutation hot-spot for the gene.

Incidence of mandibular distraction osteogenesis in Stickler Syndrome: Variation due to COL2A1 and COL11A1

OBJECTIVE

To determine whether the two most common genetic mutations seen in Stickler Syndrome (SS) (COL2A1 and COL11A1) affect the incidence of mandibular distraction osteogenesis (MDO) and what impact Robin sequence (RS) has on diagnosis. SS is an autosomal dominant connective tissue disorder characterized by almost complete penetrance. COL2A1 and COL11A1 are the two most common mutations seen in SS patients. SS often presents at birth with RS, which is characterized by the triad of micrognathia, glossoptosis, and tongue-based airway obstruction. MDO is one surgical intervention that has been shown to be successful in relieving tongue base obstruction and is the surgical intervention of choice for this condition.

METHODS

A retrospective chart review was performed on all patients with a diagnosis of SS at a tertiary pediatric hospital between January 1, 2003 and December 31, 2018. The included patient charts were reviewed for demographic information, SS mutation, and history of MDO. Forty-six patients had a clinical diagnosis of SS. Of those, 31 met inclusion criteria which involved having a molecular diagnosis of SS and sufficient follow up information to determine if MDO was indicated or performed. Twenty-two of the 31 included patients had a diagnosis of RS (70.96%). Thirteen of the 31 patients (41.94%) included in this study required MDO as a neonate.

RESULTS

Fifty-percent of patients with type I (COL2A1) required MDO as a neonate compared to only 31% of patients with type II (COL11A1), though the difference between the two groups was not statistically significant.

CONCLUSION

The findings of this study suggest that patients with type I mutation may have a higher incidence of MDO than patients with a type II mutation, though further research with larger sample sizes is needed. This information is helpful in counseling those with SS or family history of SS about what they can expect related to RS and need for MDO based on genetic findings.

LEVEL OF EVIDENCE

3.

A Missense POU4F3 Variant Associated with Autosomal Dominant Midfrequency Hearing Loss Alters Subnuclear Localization and Transcriptional Capabilities

Background

The pathogenic variant, POU class 4 transcription factor 3 (POU4F3), is reported to cause autosomal dominant nonsyndromic hearing loss (ADNSHL). Previously, we have examined a four-generation midfrequency sensorineural hearing loss (MFSNHL) family (no. 6126) and established POU4F3 c.602T>C (p.Leu201Pro) as a potential disease-causing variant.

Objectives

We explored the structural and functional alterations that the c.602T>C (p.Leu201Pro) variant enforces on the POU4F3 protein.

Methods

We utilized wild-type (WT) and mutant (MUT) POU4F3 c.602T>C plasmid incorporation into HeLa cells to assess functional changes, by immunofluorescence and luciferase assays. To predict protein structural alterations in the MUT versus WT POU4F3, we also generated 3D structures to compare both types of POU4F3 proteins.

Results

The WT POU4F3 is ubiquitously present in the nucleus, whereas the MUT form of POU4F3 exhibits a more restricted nuclear presence. This finding is different from other publications, which report a cytoplasmic localization of the MUT POU4F3. We also demonstrated that, as opposed to WT POU4F3, the MUT POU4F3 had 40% reduced luciferase activity.

Conclusions

The reduced nuclear presence, combined with reduced transcriptional activity, suggests that the POU4F3 c.602T>C variant alters cellular activity and may contribute to the pathogenicity of POU4F3-related hearing loss. It, also, provides more evidence of the pathophysiological characteristics of MFSNHL.

Familial Short Stature-A Novel Phenotype of Growth Plate Collagenopathies

CONTEXT

Collagens are the most abundant proteins in the human body. In a growth plate, collagen types II, IX, X, and XI are present. Defects in collagen genes cause heterogeneous syndromic disorders frequently associated with short stature. Less is known about oligosymptomatic collagenopathies.

OBJECTIVE

This work aims to evaluate the frequency of collagenopathies in familial short stature (FSS) children and to describe their phenotype, including growth hormone (GH) treatment response.

METHODS

Eighty-seven FSS children (pretreatment height ≤ -2 SD both in the patient and his or her shorter parent) treated with GH were included in the study. Next-generation sequencing was performed to search for variants in the COL2A1, COL9A1, COL9A2, COL9A3, COL10A1, COL11A1, and COL11A2 genes. The results were evaluated using American College of Medical Genetics and Genomics guidelines. The GH treatment response of affected children was retrospectively evaluated.

RESULTS

A likely pathogenic variant in the collagen gene was found in 10 of 87 (11.5%) children. Detailed examination described mild asymmetry with shorter limbs and mild bone dysplasia signs in 2 of 10 and 4 of 10 affected children, respectively. Their growth velocity improved from a median of 5.3 cm/year to 8.7 cm/year after 1 year of treatment. Their height improved from a median of -3.1 SD to -2.6 SD and to -2.2 SD after 1 and 3 years of therapy, respectively. The final height reached by 4 of 10 children differed by -0.67 to +1.0 SD and -0.45 to +0.5 SD compared to their pretreatment height and their affected untreated parent's height, respectively.

CONCLUSION

Oligosymptomatic collagenopathies are a frequent cause of FSS. The short-term response to GH treatment is promising.

High Myopia and Strabismus Induced by a Deep Intronic Mutation in COL2A1

Purpose: To characterize a genetic mutation causing Stickler syndrome in a previously undiagnosed family.Methods: Five generations of a single family suspected of having Stickler syndrome were evaluated clinically and genetically.Results: The demographic and clinical data yielded specific clinical phenotypes of Stickler syndrome in 13 family members; 7 had more than one clinical feature. Four family members underwent genetic analysis: the proband (index patient) and his mother, maternal grandfather, and healthy father. No relevant mutation was detected in the proband on whole exome analysis, but subsequent extension of the analysis to intronic areas yielded a deep intronic mutation, NM_001844.5:c.1527 + 135 G > A. Sanger sequencing was used to validate the results in the family members.Conclusions: Stickler syndrome has several subtypes with variable clinical features. Therefore, predicting the genetic locus of the disease based on clinical characteristics is challenging. We present a rarely described intronic mutation in COL2A1. Genetic testing may aid in the early diagnosis of Stickler syndrome, which is important for genetic counselling, proper clinical management, and improved prognosis.

Collagen XI regulates the acquisition of collagen fibril structure, organization and functional properties in tendon

Collagen XI is a fibril-forming collagen that regulates collagen fibrillogenesis. Collagen XI is normally associated with collagen II-containing tissues such as cartilage, but it also is expressed broadly during development in collagen I-containing tissues, including tendons. The goals of this study are to define the roles of collagen XI in regulation of tendon fibrillar structure and the relationship to function. A conditional Col11a1-null mouse model was created to permit the spatial and temporal manipulation of Col11a1 expression. We hypothesize that collagen XI functions to regulate fibril assembly, organization and, therefore, tendon function. Previous work using cho mice with ablated Col11a1 alleles supported roles for collagen XI in tendon fibril assembly. Homozygous cho/cho mice have a perinatal lethal phenotype that limited the studies. To circumvent this, a conditional Col11a1^flox/flox mouse model was created where exon 3 was flanked with loxP sites. Breeding with Scleraxis-Cre (Scx-Cre) mice yielded a tendon-specific Col11a1-null mouse line, Col11a1^Δten/Δten. Col11a1^flox/flox mice had no phenotype compared to wild type C57BL/6 mice and other control mice, e.g., Col11a1^flox/flox and Scx-Cre. Col11a1^flox/flox mice expressed Col11a1 mRNA at levels comparable to wild type and Scx-Cre mice. In contrast, in Col11a1^Δten/Δten mice, Col11a1 mRNA expression decreased to baseline in flexor digitorum longus tendons (FDL). Collagen XI protein expression was absent in Col11a1^Δten/Δten FDLs, and at ~50% in Col11a1^+/Δten compared to controls. Phenotypically, Col11a1^Δten/Δten mice had significantly decreased body weights (p < 0.001), grip strengths (p < 0.001), and with age developed gait impairment becoming hypomobile. In the absence of Col11a1, the tendon collagen fibrillar matrix was abnormal when analyzed using transmission electron microscopy. Reducing Col11a1 and, therefore collagen XI content, resulted in abnormal fibril structure, loss of normal fibril diameter control with a significant shift to small diameters and disrupted parallel alignment of fibrils. These alterations in matrix structure were observed in developing (day 4), maturing (day 30) and mature (day 60) mice. Altering the time of knockdown using inducible I-Col11a1^−/− mice indicated that the primary regulatory foci for collagen XI was in development. In mature Col11a1^Δten/Δten FDLs a significant decrease in the biomechanical properties was observed. The decrease in maximum stress and modulus suggest that fundamental differences in the material properties in the absence of Col11a1 expression underlie the mechanical deficiencies. These data demonstrate an essential role for collagen XI in regulation of tendon fibril assembly and organization occurring primarily during development.

Variable clinical expression of Stickler Syndrome: A case report of a novel COL11A1 mutation

Background

Stickler Syndrome is a rare connective tissue disorder, characterized by clinical, and genetic heterogeneity. The clinical expression is highly variable, including moderate to severe myopia in childhood, hearing loss, facial dysmorphic features, cleft palate, and early osteoarthritis. COL2A1, COL11A1, and COL11A2 mutations account of the majority of autosomal dominant Stickler Syndrome and, in particular, a heterozygous mutation in COL11A1 gene is identified in about 10 to 20% of Stickler Syndrome patients.

Methods

Herein, we report a case of an 8‐year‐ old child with Stickler Syndrome, presenting with early‐onset of myopia with vitreal abnormalities, facial dysmorphic characteristics, and mild hearing loss later in childhood. To identify the underlying genetic cause, Whole Exome Sequencing was carried out for COL11A1 gene.

Results

A novel de novo heterozygous splice site variant (NM_001854: c.1845 + 5G> C) of the COL11A1 gene, which had not been previously reported, was identified by Whole Exome Sequencing.

Conclusion

We reported a novel COL11A1 mutation in a child with Stickler Syndrome presenting a phenotype of early‐onset of ocular anomalies and mild hearing loss later in childhood. Our findings confirm the variability of the expression of the disease, even in the contest of the same gene‐related disorder, thus, contributing to improve the knowledge on clinical and molecular basis of this rare disease.

Mutation Spectrum of Stickler Syndrome Type I and Genotype-phenotype Analysis in East Asian Population: a systematic review

Background

Stickler syndrome is the most common genetic cause of rhegmatogenous retinal detachment (RRD) in children, and has a high risk of blindness. Type I (STL1) is the most common subtype, caused by COL2A1 mutations. This study aims to analyze the mutation spectrum of COL2A1 and further elucidate the genotype-phenotype relationships in the East Asian populations with STL1, which is poorly studied at present.

Methods

By searching MEDLINE, Web of Science, CNKI, Wanfang Data, HGMD and Clinvar, all publications associated with STL1 were collected. Then, they were carefully screened to obtain all reported STL1-related variants in COL2A1 and clinical features in East Asian patients with STL1.

Results

There were 274 COL2A1 variants identified in 999 patients with STL1 from 466 unrelated families, and more than half of them were truncation mutations. Of the 107 STL1 patients reported in the East Asian population, it was found that patients with truncation mutations had milder systemic phenotypes, whereas patients with splicing mutations had severer phenotypes. In addition, several recurrent variants (c.3106C > T, c.1833 + 1G > A, c.2710C > T and c.1693C > T) were found.

Conclusions

Genotype-phenotype correlations should certainly be studied carefully, contributed to making personalized follow-up plans and predicting prognosis of this disorder. Genome editing holds great potential for treating inherited diseases caused by pathogenic mutations. In this study, several recurrent variants were found, providing potential candidate targets for genetic manipulation in the future.

Audiologic Manifestations of Marshall Syndrome

OBJECTIVE

Marshall syndrome is a genetic disorder caused by mutations in the COL11A1 gene. This syndrome is characterized by skeletal, ophthalmologic, craniofacial, and auditory abnormalities. Hearing loss is among the main manifestations reported in this disorder being observed in approximately 80% of affected individuals.The present study aims to describe the audiologic characteristics of three members of a family with Marshall syndrome and also serves as a review of the literature.

STUDY DESIGN

Family study.

SETTING

Tertiary care otology and skull base center.

PATIENTS

We report the audiologic findings in a family with Marshall syndrome consisting of a mother and her son and daughter.

INTERVENTION(S)

The audiologic evaluation included tympanometry, acoustic reflexes testing, auditory brainstem response, transient otoacoustic emissions, pure-tone audiometry, speech audiometry in quiet, and conditioned play audiometry. These methods were applied according to the age of the patients. In addition, we provide a review of the English-language literature in an attempt to clarify the auditory phenotype of this syndrome.

RESULTS

All 3 affected individuals had heterozygous c.3816+1G>A mutation in the splicing donor site of intron 50 of the COL11A1 gene. All three patients in our study had bilateral sensorineural hearing loss. Hearing impairment ranged from mild to moderate in the daughter, moderate in the son, and from mild to moderate in their mother.

CONCLUSION

The majority of individuals with Marshall syndrome present early-onset bilateral sensorineural hearing loss. Hearing impairment is usually detected in early childhood, progresses gradually, and becomes stable in late adulthood, with a severity ranging from mild to severe.

Clinical, histopathological and genetic characterisation of oculoskeletal dysplasia in the Northern Inuit Dog

Seven Northern Inuit Dogs (NID) were diagnosed by pedigree analysis with an autosomal recessive inherited oculoskeletal dysplasia (OSD). Short-limbed dwarfism, angular limb deformities and a variable combination of macroglobus, cataracts, lens coloboma, microphakia and vitreopathy were present in all seven dogs, while retinal detachment was diagnosed in five dogs. Autosomal recessive OSD caused by COL9A3 and COL9A2 mutations have previously been identified in the Labrador Retriever (dwarfism with retinal dysplasia 1-drd1) and Samoyed dog (dwarfism with retinal dysplasia 2-drd2) respectively; both of those mutations were excluded in all affected NID. Nine candidate genes were screened in whole genome sequence data; only one variant was identified that was homozygous in two affected NID but absent in controls. This variant was a nonsense single nucleotide polymorphism in COL9A3 predicted to result in a premature termination codon and a truncated protein product. This variant was genotyped in a total of 1,232 dogs. All seven affected NID were homozygous for the variant allele (T/T), while 31/116 OSD-unaffected NID were heterozygous for the variant (C/T) and 85/116 were homozygous for the wildtype allele (C/C); indicating a significant association with OSD (p = 1.41x10-11). A subset of 56 NID unrelated at the parent level were analysed to determine an allele frequency of 0.08, estimating carrier and affected rates to be 15% and 0.6% respectively in NID. All 1,109 non-NID were C/C, suggesting the variant is rare or absent in other breeds. Expression of retinal mRNA was similar between an OSD-affected NID and OSD-unaffected non-NID. In conclusion, a nonsense variant in COL9A3 is strongly associated with OSD in NID, and appears to be widespread in this breed.

Genetic Disorders of the Extracellular Matrix

Mutations in the genes for extracellular matrix (ECM) components cause a wide range of genetic connective tissues disorders throughout the body. The elucidation of mutations and their correlation with pathology has been instrumental in understanding the roles of many ECM components. The pathological consequences of ECM protein mutations depend on its tissue distribution, tissue function, and on the nature of the mutation. The prevalent paradigm for the molecular pathology has been that there are two global mechanisms. First, mutations that reduce the production of ECM proteins impair matrix integrity largely due to quantitative ECM defects. Second, mutations altering protein structure may reduce protein secretion but also introduce dominant negative effects in ECM formation, structure and/or stability. Recent studies show that endoplasmic reticulum (ER) stress, caused by mutant misfolded ECM proteins, makes a significant contribution to the pathophysiology. This suggests that targeting ER‐stress may offer a new therapeutic strategy in a range of ECM disorders caused by protein misfolding mutations. Anat Rec, 2019. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Genetic regulation of linear growth

Linear growth occurs at the growth plate. Therefore, genetic defects that interfere with the normal function of the growth plate can cause linear growth disorders. Many genetic causes of growth disorders have already been identified in humans. However, recent genome-wide approaches have broadened our knowledge of the mechanisms of linear growth, not only providing novel monogenic causes of growth disorders but also revealing single nucleotide polymorphisms in genes that affect height in the general population. The genes identified as causative of linear growth disorders are heterogeneous, playing a role in various growth-regulating mechanisms including those involving the extracellular matrix, intracellular signaling, paracrine signaling, endocrine signaling, and epigenetic regulation. Understanding the underlying genetic defects in linear growth is important for clinicians and researchers in order to provide proper diagnoses, management, and genetic counseling, as well as to develop better treatment approaches for children with growth disorders.

Autosomal recessive Stickler syndrome resulting from a COL9A3 mutation

Stickler syndrome is a connective tissue disorder characterized by hearing loss, ocular anomalies, palatal defects, and skeletal abnormalities. The autosomal dominant form is the most common, but autosomal recessive forms have also been described. We report the second case of autosomal recessive Stickler syndrome due to homozygosity for a loss of function mutation in COL9A3, which encodes the α3 chain of type IX procollagen. The clinical features were similar to the previously described COL9A3 Stickler syndrome family, including moderate to severe sensorineural hearing loss, high myopia, and both tibial and femoral bowing at birth. Radiographs demonstrated abnormal capital femoral epiphyses and mild irregularities of the vertebral endplates. This case further establishes the phenotype associated with mutations in this gene. We suggest that loss of the α3 chain of type IX collagen results in a Stickler syndrome phenotype similar to that of the other autosomal recessive forms caused by mutations in genes encoding the α1 and α2 chains of type IX collagen.

Splice-altering variant in COL11A1 as a cause of nonsyndromic hearing loss DFNA37

PURPOSE

The aim of this study was to determine the genetic cause of autosomal dominant nonsyndromic hearing loss segregating in a multigenerational family.

METHODS

Clinical examination, genome-wide linkage analysis, and exome sequencing were carried out on the family.

RESULTS

Affected individuals presented with early-onset progressive mild hearing impairment with a fairly flat, gently downsloping or U-shaped audiogram configuration. Detailed clinical examination excluded any additional symptoms. Linkage analysis detected an interval on chromosome 1p21 with a logarithm of the odds (LOD) score of 8.29: designated locus DFNA37. Exome sequencing identified a novel canonical acceptor splice-site variant c.652-2A>C in the COL11A1 gene within the DFNA37 locus. Genotyping of all 48 family members confirmed segregation of this variant with the deafness phenotype in the extended family. The c.652-2A>C variant is novel, highly conserved, and confirmed in vitro to alter RNA splicing.

CONCLUSION

We have identified COL11A1 as the gene responsible for deafness at the DFNA37 locus. Previously, COL11A1 was solely associated with Marshall and Stickler syndromes. This study expands its phenotypic spectrum to include nonsyndromic deafness. The implications of this discovery are valuable in the clinical diagnosis, prognosis, and treatment of patients with COL11A1 pathogenic variants.

The uncommon occurrence of two common inherited disorders in a single patient: a mini case series

BACKGROUND

Inherited eye disorders are genetically determined conditions that are present from birth and usually manifest early, although some may develop later in life. Despite their low incidence, they are a common etiology of pediatric blindness. The occurrence of more than one such disease in a patient is very rare.

MATERIAL AND METHODS

Case series of two unrelated patients with simultaneous Stargardt disease (STGD1) as well as Stickler's Syndrome (SS), both genetically confirmed.

RESULTS

Patient 1: 13-year-old girl was referred for unexplained bilateral decreased vision for 6 months. She had a clinical diagnosis of SS, same as her mother. Her visual acuity was 20/200 with high myopia in both eyes. Her fundus showed foveal/perifoveal atrophy, retinal pigment epithelium (RPE) changes and beaded vitreous. Goldman visual fields (GVF) revealed enlarged blind spots with central depression. A macular dystrophy was suspected. Genetic testing revealed SS, COL11A1 gene mutation; and STGD1, ABCA4 gene mutation. Patient 2: 67-year-old female with a history of hearing loss, cleft palate, strabismus and myopia, same as her daughter and granddaughters. Her visual acuity was 20/400 and 20/250 with high myopia in both eyes. Her fundus showed macular pigment clumping and RPE atrophy with no vitreous abnormality. GVF revealed a relative central scotoma with generalized constriction. Genetic testing revealed SS, COL11A2 gene mutation; and STGD1, ABCA4 gene mutation.

CONCLUSIONS

If a patient's signs/symptoms cannot be explained by the working/known diagnosis, additional work up should be pursued for concomitant diseases. SS and STGD1 are commonly diagnosed inherited eye disorders and can coexist in one patient on rare occasions.

From Structure to Phenotype: Impact of Collagen Alterations on Human Health

The extracellular matrix (ECM) is a highly dynamic and heterogeneous structure that plays multiple roles in living organisms. Its integrity and homeostasis are crucial for normal tissue development and organ physiology. Loss or alteration of ECM components turns towards a disease outcome. In this review, we provide a general overview of ECM components with a special focus on collagens, the most abundant and diverse ECM molecules. We discuss the different functions of the ECM including its impact on cell proliferation, migration and differentiation by highlighting the relevance of the bidirectional cross-talk between the matrix and surrounding cells. By systematically reviewing all the hereditary disorders associated to altered collagen structure or resulting in excessive collagen degradation, we point to the functional relevance of the collagen and therefore of the ECM elements for human health. Moreover, the large overlapping spectrum of clinical features of the collagen-related disorders makes in some cases the patient clinical diagnosis very difficult. A better understanding of ECM complexity and molecular mechanisms regulating the expression and functions of the various ECM elements will be fundamental to fully recognize the different clinical entities.

New Genetic Diagnoses of Short Stature Provide Insights into Local Regulation of Childhood Growth

Idiopathic short stature is a common condition with a heterogeneous etiology. Advances in genetic methods, including genome sequencing techniques and bioinformatics approaches, have emerged as important tools to identify the genetic defects in families with monogenic short stature. These findings have contributed to the understanding of growth regulation and indicate that growth plate chondrogenesis, and therefore linear growth, is governed by a large number of genes important for different signaling pathways and cellular functions, including genetic defects in hormonal regulation, paracrine signaling, cartilage matrix, and fundamental cellular processes. In addition, mutations in the same gene can cause a wide phenotypic spectrum depending on the severity and mode of inheritance of the mutation.
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Novel and recurrent COL11A1 and COL2A1 mutations in the Marshall-Stickler syndrome spectrum

Marshall–Stickler syndrome represents a spectrum of inherited connective tissue disorders affecting the ocular, auditory, and skeletal systems. The syndrome is caused by mutations in the COL2A1, COL11A1, COL11A2, COL9A1, and COL9A2 genes. In this study, we examined four Turkish families with Marshall–Stickler syndrome using whole-exome sequencing and identified one COL2A1 mutation and three COL11A1 mutations. Two of the COL11A1 mutations were novel. Our findings expand our knowledge of the COL11A1 mutational spectrum that causes Marshall–Stickler syndrome.

A novel mutation in the COL2A1 gene in a patient with Stickler syndrome type 1: a case report and review of the literature

BACKGROUND

Stickler syndrome is a group of collagenopathies characterized by ophthalmic, skeletal, and orofacial abnormalities, with the degree of symptoms varying among patients. Mutations in the COL2A1, COL11A1, and COL11A2 procollagen genes cause Stickler syndrome. Marshall syndrome, caused by a COL11A1 mutation, has clinical overlap with Stickler syndrome.

CASE PRESENTATION

A 2-year-old Japanese boy was presented to our hospital with short stature (79.1 cm, -2.52 standard deviation). His past medical history was significant for soft cleft palate and bilateral cataracts. He had a flat midface, micrognathia, and limitations in bilateral elbow flexion. Radiographs showed mild spondyloepiphyseal dysplasia. Initially, we suspected Marshall syndrome, but no mutation was identified in COL11A1. At 8 years old, his height was 116.2 cm (-1.89 standard deviation), and his orofacial characteristics appeared unremarkable. We analyzed the COL2A1 gene and found a novel heterozygous mutation (c.1142 G > A, p.Gly381Asp).

CONCLUSIONS

In this case report, we identify a novel missense mutation in the COL2A1 gene in a patient with Stickler syndrome type 1, and we describe age-related changes in the clinical phenotype with regard to orofacial characteristics and height. Genetic analysis is helpful for the diagnosis of this clinically variable and genetically heterogeneous disorder.

Transcriptome profiling of the subventricular zone and dentate gyrus in an animal model of Parkinson's disease

Adult neurogenesis in the subventricular zone (SVZ), as well as in the subgranular zone contributes to brain maintenance and regeneration. In the adult brain, dopamine (DA) can regulate the endogenous neural stem cells within these two regions, while a DA deficit may affect neurogenesis. Notably, the factors that regulate in vivo neurogenesis in these subregions have not yet been fully characterized, particularly following DA depletion. In thi study, we performed RNA sequencing to investigate transcriptomic changes in the SVZ and dentate gyrus (DG) of mice in response to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). This analysis identified differentially expressed genes which were involved in the regulation of transcription, immune response, extracellular region, cell junction and myelination. These genes partially displayed different temporal profiles of expression, some of which may participate in the metabolic switch related to neurogenesis. Additionally, the mitogen-activated protein kinase (MAPK) signaling pathway was shown to be been positively regulated in the SVZ, while it was negatively affected in the DG following MPTP administration. Overall, our findings indicate that exposure to MPTP may exert different effects on transcriptome profiling between the SVZ and DG.

A novel COL11A1 missense mutation in siblings with non-ocular Stickler syndrome

Stickler syndrome (STL) is an autosomal, dominantly inherited, clinically variable and genetically heterogeneous connective tissue disorder characterized by ocular, auditory, orofacial and skeletal abnormalities. We conducted targeted resequencing using a next-generation sequencer for molecular diagnosis of a 2-year-old girl who was clinically suspected of having STL with Pierre Robin sequence. We detected a novel heterozygous missense mutation, NM_001854.3:n.4838G>A [NM_001854.3 (COL11A1_v001):c.4520G>A], in COL11A1, resulting in a Gly to Asp substitution at position 1507 [NM_001854.3(COL11A1_i001)] within one of the collagen-like domains of the triple helical region. The same mutation was detected in her 4-year-old brother with cleft palate and high-frequency sensorineural hearing loss.

Auditory phenotype in Stickler syndrome: results of audiometric analysis in 20 patients

Hearing loss in Stickler syndrome has received little attention due to the often more disabling ocular, orofacial and skeletal manifestations. Estimates suggest a global prevalence of sensorineural hearing loss (SNHL) ranging from 50 % to about 100 % though, depending on the underlying Stickler genotype. By performing extensive audiometric analysis in Stickler patients, we aimed to further elucidate the auditory phenotype. Twenty molecularly confirmed Stickler patients (age 10-62 year), of whom sixteen with type 1 Stickler syndrome (COL2A1 mutation) and four with type 2 Stickler syndrome (COL11A1 mutation) underwent an otological questionnaire, clinical examination, pure tone and speech audiometry, tympanometry and otoacoustic emission testing. Cross-sectional and longitudinal regression analysis of the audiograms was performed to assess progression. In type 1 Stickler syndrome, 75 % demonstrated hearing loss, predominantly in the high frequencies. No significant progression beyond presbyacusis was observed. All type 2 Stickler patients exhibited mild-to-moderate low- and mid-frequency SNHL and moderate-to-severe high-frequency SNHL. In both types, hearing loss was observed in childhood. Otoacoustic emissions were only detectable in 7/40 ears and had very low amplitudes, even in frequency bands with normal hearing on pure tone audiometry. Type 1 Stickler syndrome is characterized by a mild high-frequency SNHL, emerging in childhood and non-progressive. Absent otoacoustic emissions are a frequent finding. Patients with type 2 Stickler syndrome exhibit early-onset moderate SNHL affecting all frequencies with a sloping audiogram. Taking into account the visual impairment in many patients, we recommend regular auditory follow-up in patients with Stickler syndrome, especially in childhood.

A pilot study of gene testing of genetic bone dysplasia using targeted next-generation sequencing

Molecular diagnosis of genetic bone dysplasia is challenging for non-expert. A targeted next-generation sequencing technology was applied to identify the underlying molecular mechanism of bone dysplasia and evaluate the contribution of these genes to patients with bone dysplasia encountered in pediatric endocrinology. A group of unrelated patients (n=82), characterized by short stature, dysmorphology and X-ray abnormalities, of which mucopolysacharidoses, GM1 gangliosidosis, mucolipidosis type II/III and achondroplasia owing to FGFR3 G380R mutation had been excluded, were recruited in this study. Probes were designed to 61 genes selected according to the nosology and classification of genetic skeletal disorders of 2010 by Illumina's online DesignStudio software. DNA was hybridized with probes and then a library was established following the standard Illumina protocols. Amplicon library was sequenced on a MiSeq sequencing system and the data were analyzed by MiSeq Reporter. Mutations of 13 different genes were found in 44 of the 82 patients (54%). Mutations of COL2A1 gene and PHEX gene were found in nine patients, respectively (9/44=20%), followed by COMP gene in 8 (18%), TRPV4 gene in 4 (9%), FBN1 gene in 4 (9%), COL1A1 gene in 3 (6%) and COL11A1, TRAPPC2, MATN3, ARSE, TRPS1, SMARCAL1, ENPP1 gene mutations in one patient each (2% each). In conclusion, mutations of COL2A1, PHEX and COMP gene are common for short stature due to bone dysplasia in outpatient clinics in pediatric endocrinology. Targeted next-generation sequencing is an efficient way to identify the underlying molecular mechanism of genetic bone dysplasia.

The utility of mouse models to provide information regarding the pathomolecular mechanisms in human genetic skeletal diseases: The emerging role of endoplasmic reticulum stress (Review)

Genetic skeletal diseases (GSDs) are an extremely diverse and complex group of rare genetic diseases that primarily affect the development and homeostasis of the osseous skeleton. There are more than 450 unique and well-characterised phenotypes that range in severity from relatively mild to severe and lethal forms. Although individually rare, as a group of related genetic diseases, GSDs have an overall prevalence of at least 1 per 4,000 children. Qualitative defects in cartilage structural proteins result in a broad spectrum of both recessive and dominant GSDs. This review focused on a disease spectrum resulting from mutations in the non-collagenous glycoproteins, cartilage oligomeric matrix protein (COMP) and matrilin-3, which together cause a continuum of phenotypes that are amongst the most common autosomal dominant GSDs. Pseudoachondroplasia (PSACH) and autosomal dominant multiple epiphyseal dysplasia (MED) comprise a disease spectrum characterised by varying degrees of disproportionate short stature, joint pain and stiffness and early-onset osteoarthritis. Over the past decade, the generation and deep phenotyping of a range of genetic mouse models of the PSACH and MED disease spectrum has allowed the disease mechanisms to be characterised in detail. Moreover, the generation of novel phenocopies to model specific disease mechanisms has confirmed the importance of endoplasmic reticulum (ER) stress and reduced chondrocyte proliferation as key modulators of growth plate dysplasia and reduced bone growth. Finally, new insight into related musculoskeletal complications (such as myopathy and tendinopathy) has also been gained through the in-depth analysis of targeted mouse models of the PSACH-MED disease spectrum.

Novel pathogenic COL11A1/COL11A2 variants in Stickler syndrome detected by targeted NGS and exome sequencing

INTRODUCTION

Stickler syndrome is caused by mutations in genes encoding type II and type XI collagens. About 85% of the pathogenic variants is found in COL2A1 (Stickler type 1), whereas a minority of mutations has been reported in COL11A1 (Stickler type 2) and COL11A2 (Stickler type 3). Beside the typical skeletal and orofacial manifestations, ocular anomalies are predominantly present in type 1 and type 2, while hearing loss is more pronounced in type 2 and type 3.

METHODS

We performed COL11A1 mutation analysis for 40 type 2 Stickler patients and COL11A2 mutation analysis for five type 3 Stickler patients, previously all COL2A1 mutation-negative, using targeted next-generation sequencing (NGS) whereas whole-exome sequencing (WES) was performed in parallel for two patients. Three patients were analyzed for both genes due to unclear ocular findings.

RESULTS

In total 14 COL11A1 and two COL11A2 mutations could be identified, seven of which are novel. Splice site alterations are the most frequent mutation type, followed by glycine substitutions. In addition, six variants of unknown significance (VUS) have been found. Identical mutations and variants were identified with both NGS techniques.

CONCLUSION

We expand the mutation spectrum of COL11A1 and COL11A2 in Stickler syndrome patients and show that targeted NGS is an efficient and cost-effective molecular tool in the genetic diagnosis of Stickler syndrome, whereas the more standardized WES might be an alternative approach.

Marshall syndrome: further evidence of a distinct phenotypic entity and report of new findings

Marshall syndrome and type II Stickler syndrome are caused by mutations in COL11A1, which codes for the proα1chain of collagen XI. Collagen XI is a minor fibrillar collagen co-expressed with collagen II in cartilage and the vitreous of the eye. Characteristic features of Marshall syndrome include midfacial hypoplasia, high myopia, and sensorineural-hearing deficit. Deletions, insertions, splice site, and missense mutations in COL11A1 have been identified in Stickler syndrome and Marshall syndrome patients. In this study, we describe the clinical presentations of seven patients with Marshall syndrome from three unrelated Saudi families, inherited as autosomal dominant (two families) and autosomal recessive (one family). Cardinal clinical features of Marshall syndrome are manifested in all patients. One patient had ectodermal abnormalities. Mutations (c.2702G > A in exon 34,IVS50 + 1G > A, and IVS50 + lG > C) were identified in COL11A1 in affected members. Interestingly, the first report of autosomal recessive Marshall syndrome was from Saudi Arabia caused by the same mutation (c.2702G > A, p.Gly901Glu) as in one of our families. This study depicts detailed phenotypic and genetic description of dominant and recessive forms of Marshall syndrome due to COL11A1 mutations.

Association of type XI collagen genes with chronic Achilles tendinopathy in independent populations from South Africa and Australia

BACKGROUND

Type XI collagen, which is expressed in developing tendons and is encoded by the COL11A1, COL11A2 and COL2A1 genes, shares structural and functional homology with type V collagen, which plays an important role in collagen fibril assembly. We investigated the association of these three polymorphisms with Achilles tendinopathy (AT) and whether these polymorphisms interact with COL5A1 to modulate the risk of AT.

METHODS

184 participants diagnosed with chronic AT (TEN) and 338 appropriately matched asymptomatic controls (CON) were genotyped for the three polymorphisms.

RESULTS

Although there were no independent associations with AT, the TCT pseudohaplotype constructed from rs3753841 (T/C), rs1676486 (C/T) and rs1799907 (T/A) was significantly over-represented (p=0.006) in the TEN (25.9%) compared with the CON (17.1%) group. The TCT(AGGG) pseudohaplotypes constructed using these type XI collagen polymorphisms and the functional COL5A1 rs71746744 (-/AGGG) polymorphism were also significantly over-represented (p<0.001) in the TEN (25.2%) compared with the CON (9.1%) group.

DISCUSSION

The genes encoding structural and functionally related type XI (COL11A1 and COL11A2) and type V (COL5A1) collagens interact with one another to collectively modulate the risk for AT. Although there are no immediate clinical applications, the results of this study provide additional evidence that interindividual variations in collagen fibril assembly might be an important molecular mechanism in the aetiology of chronic AT.

Hearing impairment in Stickler syndrome: a systematic review

Background

Stickler syndrome is a connective tissue disorder characterized by ocular, skeletal, orofacial and auditory defects. It is caused by mutations in different collagen genes, namely COL2A1, COL11A1 and COL11A2 (autosomal dominant inheritance), and COL9A1 and COL9A2 (autosomal recessive inheritance). The auditory phenotype in Stickler syndrome is inconsistently reported. Therefore we performed a systematic review of the literature to give an up-to-date overview of hearing loss in Stickler syndrome, and correlated it with the genotype.

Methods

English-language literature was reviewed through searches of PubMed and Web of Science, in order to find relevant articles describing auditory features in Stickler patients, along with genotype. Prevalences of hearing loss are calculated and correlated with the different affected genes and type of mutation.

Results

313 patients (102 families) individually described in 46 articles were included. Hearing loss was found in 62.9%, mostly mild to moderate when reported. Hearing impairment was predominantly sensorineural (67.8%). Conductive (14.1%) and mixed (18.1%) hearing loss was primarily found in young patients or patients with a palatal defect. Overall, mutations in COL11A1 (82.5%) and COL11A2 (94.1%) seem to be more frequently associated with hearing impairment than mutations in COL2A1 (52.2%).

Conclusions

Hearing impairment in patients with Stickler syndrome is common. Sensorineural hearing loss predominates, but also conductive hearing loss, especially in children and patients with a palatal defect, may occur. The distinct disease-causing collagen genes are associated with a different prevalence of hearing impairment, but still large phenotypic variation exists. Regular auditory follow-up is strongly advised, particularly because many Stickler patients are visually impaired.

Clinical and molecular analysis of UAE fibrochondrogenesis patients expands the phenotype and reveals two COL11A1 homozygous null mutations

Fibrochondrogenesis is documented to be a neonatally lethal rare recessively inherited disorder characterized by short-limbed skeletal dysplasia. Here we report two patients from two unrelated consanguineous Emirati families who have unexpectedly survived till the ages of 3 and 6 years. These patients show additional symptoms which include developmental delay, profound sensory-neural deafness, severe myopia and progressive severe skeletal abnormalities. Linkage of fibrochondrogenesis in the Emirati families to chromosome 1 has been established using homozygosity mapping confirming recent findings by Tompson et al. in 2010. Screening of the COL11A1 gene revealed two null homozygous mutations [c.4084C>T (p.R1362X) and c.3708+437T>G] in the aforementioned two families. The c.4084C>T mutation is predicted to introduce a stop codon at position Arg1362, whereas the c.3708+437T>G mutation causes the activation of an intronic pseudoexon between exons 48 and 49. This resulted in the insertion of 50 nucleotides into the mRNA. The carriers of these mutations display ocular defects with normal hearing. In conclusion, our data shall improve the overall understanding of fibrochondrogenesis especially in surviving homozygous patients and, at least partly, explain the phenotypic variability associated with COL11A1 gene mutations.

A loss of function mutation in the COL9A2 gene causes autosomal recessive Stickler syndrome

Stickler syndrome is characterized by ocular, auditory, skeletal, and orofacial abnormalities. We describe a family with autosomal recessive Stickler syndrome. The main clinical findings consisted of high myopia, vitreoretinal degeneration, retinal detachment, hearing loss, and short stature. Affected family members were found to have a homozygous loss-of-function mutation in COL9A2, c.843_c.846 + 4del8. A family with autosomal recessive Stickler syndrome was previously described and found to have a homozygous loss-of-function mutation in COL9A1. COL9A1, COL9A2, and COL9A3 code for collagen IX. All three collagen IX α chains, α1, α2, and α3, are needed for formation of functional collagen IX molecule. In dogs, two causative loci have been identified in autosomal recessive oculoskeletal dysplasia. This dysplasia resembles Stickler syndrome. Recently, homozygous loss-of-function mutations in COL9A2 and COL9A3 were found to co-segregate with the loci. Together the data from the present study and the previous studies suggest that loss-of-function mutations in any of the collagen IX genes can cause autosomal recessive Stickler syndrome.

Fibrochondrogenesis results from mutations in the COL11A1 type XI collagen gene

Fibrochondrogenesis is a severe, autosomal-recessive, short-limbed skeletal dysplasia. In a single case of fibrochondrogenesis, whole-genome SNP genotyping identified unknown ancestral consanguinity by detecting three autozygous regions. Because of the predominantly skeletal nature of the phenotype, the 389 genes localized to the autozygous intervals were prioritized for mutation analysis by correlation of their expression with known cartilage-selective genes via the UCLA Gene Expression Tool, UGET. The gene encoding the α1 chain of type XI collagen (COL11A1) was the only cartilage-selective gene among the three candidate intervals. Sequence analysis of COL11A1 in two genetically independent fibrochondrogenesis cases demonstrated that each was a compound heterozygote for a loss-of-function mutation on one allele and a mutation predicting substitution for a conserved triple-helical glycine residue on the other. The parents who were carriers of missense mutations had myopia. Early-onset hearing loss was noted in both parents who carried a loss-of-function allele, suggesting COL11A1 as a locus for mild, dominantly inherited hearing loss. These findings identify COL11A1 as a locus for fibrochondrogenesis and indicate that there might be phenotypic manifestations among carriers.

Secreted phosphoprotein 1 upstream invasive network construction and analysis of lung adenocarcinoma compared with human normal adjacent tissues by integrative biocomputation

The aim of this study is to set up single molecular secreted phosphoprotein 1 (SPP1) upstream invasive network of lung adenocarcinoma. This paper proposed an integrated method based on linear programming and a decomposition procedure with integrated analysis of the significant function cluster using Kappa statistics and fuzzy heuristic clustering. Our study proved that only modules appearing in lung adenocarcinoma include cytokine module (CXCL13, GREM1_2 inhibition), cell adhesion module (COL11A1_2 activation; CDH3 inhibition), and receptor binding module (NMU activation; CXCL13, GREM1_2 inhibition), which increase the invasion of cancer cell. We compared skeletal development, signal, biological regulation, sequence variant modules between human normal adjacent tissues and lung adenocarcinoma. SPP1 skeletal development module appears in human normal adjacent tissues (COL11A1_1 activation; COL10A1 inhibition), whereas in lung adenocarcinoma (COL11A1_2, COL1A2 activation); signal module appears in human normal adjacent tissues (COL11A1_1, CXCL13, MMP11, SPINK1 activation; COL10A1, COL3A1 inhibition), whereas in lung adenocarcinoma (COL11A1_2, COL1A2, MMP12 activation; CDH3, CXCL13, GREM1_2, MMP11, SPINK1 inhibition); biological regulation module appears in human normal adjacent tissues (CXCL13, MKI67, PYCR1 activation; NEK2, SPDEF, TOP2A_2, TOX3_1 inhibition), whereas in lung adenocarcinoma (HMGB3, MKI67, NMU, PYCR1, TOX3_2 activation; CXCL13, SPDEF, TOP2A_2 inhibition); sequence variant module appears in human normal adjacent tissues (COL11A1_1, MKI67, MMP11 activation; ASPM, COL10A1, COL3A1, NEK2, TMPRSS4, TOP2A_2 inhibition), whereas in lung adenocarcinoma (COL11A1_2, COL1A2, HMMR, MKI67, MMP12 activation; ABCC3, ASPM, CDH3, MMP11, TOP2A_2 inhibition). It can be deduced that modules above in human normal adjacent tissues reflect the invasive inhibition of normal cells, whereas in lung adenocarcinoma increase the invasion of cancer cell. Our study of SPP1 upstream invasive network may be useful to identify novel and potentially targets for prognosis and therapy of lung adenocarcinoma.