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Mutations in CDK5RAP2 cause Seckel syndrome.

Yigit G, Brown KE, Kayserili H, Pohl E, Caliebe A, Zahnleiter D, Rosser E, Bögershausen N, Uyguner ZO, Altunoglu U, Nürnberg G, Nürnberg P, Rauch A, Li Y, Thiel CT, Wollnik B - Mol Genet Genomic Med (2015)

Bottom Line: CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly.Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152.This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152.

View Article: PubMed Central - PubMed

Affiliation: Institute of Human Genetics, University of Cologne Cologne, Germany ; Center for Molecular Medicine Cologne (CMMC), University of Cologne Cologne, Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne Cologne, Germany.

ABSTRACT
Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152.

No MeSH data available.


Related in: MedlinePlus

Transcriptional consequences of identified c.4005-9A>G mutation in CDK5RAP2. (A) Left: Electropherogram of cDNA derived from the CDK5RAP2 transcript from patient II.1 of family SK-1 carrying the homozygous CDK5RAP2 c.4005-9A>G mutation shows alternative splicing of exon 27 leading to an 8 bp insertion and thereby to a frame-shift and a premature stop codon. Right: Schematic representation of the alternatively spliced transcript. (B) Results from the exon-trapping assay. Left: Electropherograms of cDNA-PCR products generated from the wild-type and mutant constructs: The c.4005-9A>G mutation leads to a complete loss of the original splice-site and to insertion of 8 bp. The previously described c.4005-15A>G mutation has a similar effect leading to insertion of 14 bp. Right: Schematic representation of the constructs used for the assay and of the observed alternatively spliced transcripts. Exon A and exon B represent artificial exons of the pSPL3 splicing vector.
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fig03: Transcriptional consequences of identified c.4005-9A>G mutation in CDK5RAP2. (A) Left: Electropherogram of cDNA derived from the CDK5RAP2 transcript from patient II.1 of family SK-1 carrying the homozygous CDK5RAP2 c.4005-9A>G mutation shows alternative splicing of exon 27 leading to an 8 bp insertion and thereby to a frame-shift and a premature stop codon. Right: Schematic representation of the alternatively spliced transcript. (B) Results from the exon-trapping assay. Left: Electropherograms of cDNA-PCR products generated from the wild-type and mutant constructs: The c.4005-9A>G mutation leads to a complete loss of the original splice-site and to insertion of 8 bp. The previously described c.4005-15A>G mutation has a similar effect leading to insertion of 14 bp. Right: Schematic representation of the constructs used for the assay and of the observed alternatively spliced transcripts. Exon A and exon B represent artificial exons of the pSPL3 splicing vector.

Mentions: To confirm the functional consequence of the identified c.4005-9A>G mutation, we analyzed the cDNA of the index patient of family SK-1 (II.1, Fig.1A), and we showed that this mutation creates a new, stronger acceptor splice-site which completely abolishes the use of the original acceptor site. As predicted, this leads to the insertion of 8 bp, causing a frame-shift and premature truncation of the protein (p.Arg1335Serfs*3, Fig.3A).


Mutations in CDK5RAP2 cause Seckel syndrome.

Yigit G, Brown KE, Kayserili H, Pohl E, Caliebe A, Zahnleiter D, Rosser E, Bögershausen N, Uyguner ZO, Altunoglu U, Nürnberg G, Nürnberg P, Rauch A, Li Y, Thiel CT, Wollnik B - Mol Genet Genomic Med (2015)

Transcriptional consequences of identified c.4005-9A>G mutation in CDK5RAP2. (A) Left: Electropherogram of cDNA derived from the CDK5RAP2 transcript from patient II.1 of family SK-1 carrying the homozygous CDK5RAP2 c.4005-9A>G mutation shows alternative splicing of exon 27 leading to an 8 bp insertion and thereby to a frame-shift and a premature stop codon. Right: Schematic representation of the alternatively spliced transcript. (B) Results from the exon-trapping assay. Left: Electropherograms of cDNA-PCR products generated from the wild-type and mutant constructs: The c.4005-9A>G mutation leads to a complete loss of the original splice-site and to insertion of 8 bp. The previously described c.4005-15A>G mutation has a similar effect leading to insertion of 14 bp. Right: Schematic representation of the constructs used for the assay and of the observed alternatively spliced transcripts. Exon A and exon B represent artificial exons of the pSPL3 splicing vector.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585455&req=5

fig03: Transcriptional consequences of identified c.4005-9A>G mutation in CDK5RAP2. (A) Left: Electropherogram of cDNA derived from the CDK5RAP2 transcript from patient II.1 of family SK-1 carrying the homozygous CDK5RAP2 c.4005-9A>G mutation shows alternative splicing of exon 27 leading to an 8 bp insertion and thereby to a frame-shift and a premature stop codon. Right: Schematic representation of the alternatively spliced transcript. (B) Results from the exon-trapping assay. Left: Electropherograms of cDNA-PCR products generated from the wild-type and mutant constructs: The c.4005-9A>G mutation leads to a complete loss of the original splice-site and to insertion of 8 bp. The previously described c.4005-15A>G mutation has a similar effect leading to insertion of 14 bp. Right: Schematic representation of the constructs used for the assay and of the observed alternatively spliced transcripts. Exon A and exon B represent artificial exons of the pSPL3 splicing vector.
Mentions: To confirm the functional consequence of the identified c.4005-9A>G mutation, we analyzed the cDNA of the index patient of family SK-1 (II.1, Fig.1A), and we showed that this mutation creates a new, stronger acceptor splice-site which completely abolishes the use of the original acceptor site. As predicted, this leads to the insertion of 8 bp, causing a frame-shift and premature truncation of the protein (p.Arg1335Serfs*3, Fig.3A).

Bottom Line: CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly.Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152.This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152.

View Article: PubMed Central - PubMed

Affiliation: Institute of Human Genetics, University of Cologne Cologne, Germany ; Center for Molecular Medicine Cologne (CMMC), University of Cologne Cologne, Germany ; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne Cologne, Germany.

ABSTRACT
Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152.

No MeSH data available.


Related in: MedlinePlus