Homozygous variant in C21orf2 in a case of Jeune syndrome with severe thoracic involvement: extending the phenotypic spectrum

Mcinerney-Leo, Aideen M., Wheeler, Lawrie, Marshall, Mhairi S., Anderson, Lisa K., Zankl, Andreas, Brown, Matthew A., Leo, Paul J., Wicking, Carol and Duncan, Emma L. (2017) Homozygous variant in C21orf2 in a case of Jeune syndrome with severe thoracic involvement: extending the phenotypic spectrum. American Journal of Medical Genetics, 173 6: 1698-1704. doi:10.1002/ajmg.a.38215


Author Mcinerney-Leo, Aideen M.
Wheeler, Lawrie
Marshall, Mhairi S.
Anderson, Lisa K.
Zankl, Andreas
Brown, Matthew A.
Leo, Paul J.
Wicking, Carol
Duncan, Emma L.
Title Homozygous variant in C21orf2 in a case of Jeune syndrome with severe thoracic involvement: extending the phenotypic spectrum
Formatted title
Homozygous variant in C21orf2 in a case of Jeune syndrome with severe thoracic involvement: extending the phenotypic spectrum
Journal name American Journal of Medical Genetics   Check publisher's open access policy
ISSN 1552-4833
1552-4825
Publication date 2017-04-19
Sub-type Article (original research)
DOI 10.1002/ajmg.a.38215
Open Access Status Not yet assessed
Volume 173
Issue 6
Start page 1698
End page 1704
Total pages 7
Place of publication Hoboken, NJ, United States
Publisher John Wiley & Sons
Language eng
Subject 1311 Genetics
2716 Genetics (clinical)
Abstract We previously reported exome sequencing in a short-rib thoracic dystrophy (SRTD) cohort, in whom recessive mutations were identified in SRTD-associated genes in 10 of 11 cases. A heterozygous stop mutation in the known SRTD gene WDR60 was identified in the remaining case; no novel candidate gene/s were suggested by homozygous/compound heterozygous analysis. This case was thus considered unsolved. Re-analysis following an analysis pipeline update identified a homozygous mutation in C21orf2 (c.218G > C; p.Arg73Pro). This homozygous variant was previously removed at the quality control stage by the default GATK parameter “in-breeding co-efficient.” C21orf2 was recently associated with both Jeune asphyxiating thoracic dystrophy (JATD) and axial spondylometaphyseal dysplasia (axial SMD); this particular mutation was reported in homozygous and compound heterozygous state in both conditions. Our case has phenotypic features of both JATD and axial SMD; and the extent of thoracic involvement appears more severe than in other C21orf2-positive cases. Identification of a homozygous C21orf2 mutation in this case emphasizes the value of exome sequencing for simultaneously screening known genes and identifying novel genes. Additionally, it highlights the importance of re-interrogating data both as novel gene associations are identified and as analysis pipelines are refined. Finally, the severity of thoracic restriction in this case adds to the phenotypic spectrum attributable to C21orf2 mutations.
Formatted abstract
We previously reported exome sequencing in a short-rib thoracic dystrophy (SRTD) cohort, in whom recessive mutations were identified in SRTD-associated genes in 10 of 11 cases. A heterozygous stop mutation in the known SRTD gene WDR60 was identified in the remaining case; no novel candidate gene/s were suggested by homozygous/compound heterozygous analysis. This case was thus considered unsolved. Re-analysis following an analysis pipeline update identified a homozygous mutation in C21orf2 (c.218G>C; p.Arg73Pro). This homozygous variant was previously removed at the quality control stage by the default GATK parameter "in-breeding co-efficient." C21orf2 was recently associated with both Jeune asphyxiating thoracic dystrophy (JATD) and axial spondylometaphyseal dysplasia (axial SMD); this particular mutation was reported in homozygous and compound heterozygous state in both conditions. Our case has phenotypic features of both JATD and axial SMD; and the extent of thoracic involvement appears more severe than in other C21orf2-positive cases. Identification of a homozygous C21orf2 mutation in this case emphasizes the value of exome sequencing for simultaneously screening known genes and identifying novel genes. Additionally, it highlights the importance of re-interrogating data both as novel gene associations are identified and as analysis pipelines are refined. Finally, the severity of thoracic restriction in this case adds to the phenotypic spectrum attributable to C21orf2 mutations.
Keyword C21orf2
Ciliopathy
Exome sequencing
Jeune syndrome
Short-rib polydactyly
Spondylometaphyseal dysplasia
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

 
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