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Heterozygous mutations in the gene encoding noggin affect human joint morphogenesis
Y Gong1, D Krakow, J Marcelino
1Department of Genetics and Center for Human Genetics, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, Ohio, USA.
Nature Genetics
|March 18, 1999
Summary
The secreted protein noggin is crucial for proper joint formation. Mutations in the NOG gene cause skeletal abnormalities like joint fusion in humans and mice.
Area of Science:
- Developmental biology
- Genetics
- Skeletal biology
Background:
- The secreted polypeptide noggin (Nog) inhibits transforming growth factor beta superfamily members (TGFbeta-FMs), like BMP4.
- Noggin's efficient diffusion suggests a role in creating morphogenic gradients during embryonic development.
- Nog gene expression occurs at multiple sites during mouse embryogenesis, including developing bones.
Purpose of the Study:
- To investigate the role of noggin in skeletal development and joint formation.
- To identify human NOG mutations associated with skeletal disorders.
Main Methods:
- Identification of dominant human NOG mutations in families with proximal symphalangism (SYM1) and multiple synostoses syndrome (SYNS1).
- Analysis of a de novo NOG mutation in a patient with unaffected parents.
- Examination of evolutionary conservation of mutated amino acid residues.
Main Results:
- Five dominant NOG mutations were identified in families with SYM1.
- A de novo NOG mutation was found in a patient with unaffected parents.
- A dominant NOG mutation was identified in a family with SYNS1.
- All seven identified NOG mutations affect evolutionarily conserved amino acid residues.
- Noggin is essential for joint formation, with mutations leading to joint fusion.
Conclusions:
- NOG mutations are causative for proximal symphalangism and multiple synostoses syndrome.
- The study confirms NOG's essential role in joint formation.
- Skeletal development requirements for noggin may vary across species and skeletal elements.