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Gonadal mosaicism in pseudoachondroplasia
1Department of Medical Genetics, University of British Columbia, Vancouver, Canada.
American Journal of Medical Genetics
|September 1, 1987
Summary
Pseudoachondroplasia, a skeletal dysplasia, can occur without family history due to gonadal mosaicism. This genetic phenomenon explains apparent new mutations in pseudoachondroplasia cases.
Area of Science:
- Genetics
- Skeletal Dysplasias
- Human Genetics
Background:
- Pseudoachondroplasia is a rare skeletal dysplasia.
- Typically inherited in an autosomal dominant pattern.
- This study investigates an unusual family presentation.
Observation:
- A brother and sister presented with pseudoachondroplasia, despite having unaffected parents.
- The affected brother and his unaffected wife had two daughters, one with pseudoachondroplasia and one unaffected.
- This pattern suggests a genetic cause beyond typical dominant inheritance.
Findings:
- The most probable explanation for this family's pseudoachondroplasia cases is gonadal (germinal cell) mosaicism in one of the parents.
- Review of literature suggests a small percentage of pseudoachondroplasia cases initially presumed to be new mutations may result from gonadal mosaicism.
- Autosomal recessive inheritance is also considered but less likely in this specific family.
Implications:
- Gonadal mosaicism should be considered in the genetic counseling for pseudoachondroplasia, especially in sporadic cases.
- Understanding mosaicism refines recurrence risk assessment for families with skeletal dysplasias.
- This finding broadens the etiological spectrum of pseudoachondroplasia.