Dataset Information

Molecular screening of ADAMTSL2 gene in 33 patients reveals the genetic heterogeneity of geleophysic dysplasia.

ABSTRACT:

Background

Geleophysic dysplasia (GD, OMIM 231050) is an autosomal recessive disorder characterised by short stature, small hands and feet, stiff joints, and thick skin. Patients often present with a progressive cardiac valvular disease which can lead to an early death. In a previous study including six GD families, we have mapped the disease gene on chromosome 9q34.2 and identified mutations in the A Disintegrin And Metalloproteinase with Thrombospondin repeats-like 2 gene (ADAMTSL2).

Methods

Following this study, we have collected the samples of 30 additional GD families, including 33 patients and identified ADAMTSL2 mutations in 14/33 patients, comprising 13 novel mutations. The absence of mutation in 19 patients prompted us to compare the two groups of GD patients, namely group 1, patients with ADAMTSL2 mutations (n=20, also including the 6 patients from our previous study), and group 2, patients without ADAMTSL2 mutations (n=19).

Results

The main discriminating features were facial dysmorphism and tip-toe walking, which were almost constantly observed in group 1. No differences were found concerning heart involvement, skin thickness, recurrent respiratory and ear infections, bronchopulmonary insufficiency, laryngo-tracheal stenosis, deafness, and radiographic features.

Conclusions

It is concluded that GD is a genetically heterogeneous condition. Ongoing studies will hopefully lead to the identification of another disease gene.

SUBMITTER: Allali S

PROVIDER: S-EPMC4413937 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Publications

Molecular screening of ADAMTSL2 gene in 33 patients reveals the genetic heterogeneity of geleophysic dysplasia.

Allali Slimane S Le Goff Carine C Pressac-Diebold Isabelle I Pfennig Gwendoline G Mahaut Clémentine C Dagoneau Nathalie N Alanay Yasemin Y Brady Angela F AF Crow Yanick J YJ Devriendt Koen K Drouin-Garraud Valérie V Flori Elisabeth E Geneviève David D Hennekam Raoul C RC Hurst Jane J Krakow Deborah D Le Merrer Martine M Lichtenbelt Klaske D KD Lynch Sally A SA Lyonnet Stanislas S MacDermot Kay K Mansour Sahar S Megarbané André A Santos Heloisa G HG Splitt Miranda M Superti-Furga Andrea A Unger Sheila S Williams Denise D Munnich Arnold A Cormier-Daire Valérie V

Journal of medical genetics 20110317 6

<h4>Background</h4>Geleophysic dysplasia (GD, OMIM 231050) is an autosomal recessive disorder characterised by short stature, small hands and feet, stiff joints, and thick skin. Patients often present with a progressive cardiac valvular disease which can lead to an early death. In a previous study including six GD families, we have mapped the disease gene on chromosome 9q34.2 and identified mutations in the A Disintegrin And Metalloproteinase with Thrombospondin repeats-like 2 gene (ADAMTSL2).<h ...[more]

PMID: 21415077

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Project description:Mutations in the secreted glycoprotein ADAMTSL2 cause recessive geleophysic dysplasia (GD) in humans and Musladin-Lueke syndrome (MLS) in dogs. GD is a severe, often lethal, condition presenting with short stature, brachydactyly, stiff skin, joint contractures, tracheal-bronchial stenosis and cardiac valve anomalies, whereas MLS is non-lethal and characterized by short stature and severe skin fibrosis. Although most mutations in fibrillin-1 (FBN1) cause Marfan syndrome (MFS), a microfibril disorder leading to transforming growth factor-β (TGFβ) dysregulation, domain-specific FBN1 mutations result in dominant GD. ADAMTSL2 has been previously shown to bind FBN1 and latent TGFβ-binding protein-1 (LTBP1). Here, we investigated mice with targeted Adamtsl2 inactivation as a new model for GD (Adamtsl2(-/-) mice). An intragenic lacZ reporter in these mice showed that ADAMTSL2 was produced exclusively by bronchial smooth muscle cells during embryonic lung development. Adamtsl2(-/-) mice, which died at birth, had severe bronchial epithelial dysplasia with abnormal glycogen-rich inclusions in bronchial epithelium resembling the cellular anomalies described previously in GD. An increase in microfibrils in the bronchial wall was associated with increased FBN2 and microfibril-associated glycoprotein-1 (MAGP1) staining, whereas LTBP1 staining was increased in bronchial epithelium. ADAMTSL2 was shown to bind directly to FBN2 with an affinity comparable to FBN1. The observed extracellular matrix (ECM) alterations were associated with increased bronchial epithelial TGFβ signaling at 17.5 days of gestation; however, treatment with TGFβ-neutralizing antibody did not correct the epithelial dysplasia. These investigations reveal a new function of ADAMTSL2 in modulating microfibril formation, and a previously unsuspected association with FBN2. Our studies suggest that the bronchial epithelial dysplasia accompanying microfibril dysregulation in Adamtsl2(-/-) mice cannot be reversed by TGFβ neutralization, and thus might be mediated by other mechanisms.

Project description:A disintegrin-like and metalloprotease domain with thrombospondin type 1 repeats-like 2 (ADAMTSL2) is a matricellular protein that interacts with latent TGF-b binding protein 1 and fibrillin-1. ADAMTSL2 mutations cause an autosomal recessive connective tissue disorder named geleophysic dysplasia 1 (GPHYSD1, OMIM #231050), which is characterized by short stature, small hands and feet, and cardiac defects. ADAMTSL2 contains seven thrombospondin type-1 repeats (TSRs), six of which contain the consensus sequence for serine or threonine glycosylation by protein O-fucosyltransferase 2 (POFUT2). O-fucose modified TSRs are subsequently elongated to a Glucose1-3Fucose (GlcFuc) disaccharide by b3-glucosyltransferase (B3GLCT). B3GLCT mutations cause Peters Plus Syndrome (PTRPLS, OMIM #261540), which is characterized by skeletal defects similar to those of GPHYSD1. Several ADAMTSL2 TSRs have consensus sequences for C-mannosylation, and one TSR contains a sequon for N-glycosylation that overlaps with an O-fucosylation site. Six reported GPHYSD1 mutations occur within the TSRs and two lie near O-fucosylation sites. To investigate the effects of TSR glycosylation on ADAMTSL2 function, we used mass spectrometry to identify glycan modifications at the predicted consensus sequences. We found that most TSRs were modified with the GlcFuc disaccharide at high stoichiometry at O-fucosylation sites and variable mannose stoichiometry at C-mannosylation sites. Loss of ADAMTSL2 secretion in POFUT2 knockout but not in B3GLCT knockout cells suggested that impaired ADAMTSL2 secretion is not responsible for skeletal defects in PTRPLS patients lacking B3GLCT. In contrast, secretion of mouse ADAMTSL2 carrying GPHYSD1 mutations (S641L in TSR3 and G817R in TSR6) was significantly reduced in HEK293T cells. Moreover, S641L eliminated O-fucosylation of TSR3. Combined these results provide strong evidence that developmental abnormalities in GPHYSD1 patients with this mutation are caused by loss of O-fucosylation on TSR3 and impaired ADAMTSL2 secretion.

Dataset Information

Molecular screening of ADAMTSL2 gene in 33 patients reveals the genetic heterogeneity of geleophysic dysplasia.

Background

Methods

Results

Conclusions

Publications

Molecular screening of ADAMTSL2 gene in 33 patients reveals the genetic heterogeneity of geleophysic dysplasia.

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