Whole exome sequencing identifies a mutation for a novel form of corneal intraepithelial dyskeratosis.
BACKGROUND
Corneal intraepithelial dyskeratosis is an extremely rare condition. The classical form, affecting Native American Haliwa-Saponi tribe members, is called hereditary benign intraepithelial dyskeratosis (HBID). Herein, we present a new form of corneal intraepithelial dyskeratosis for which we identified the causative gene by using deep sequencing technology.


RESULTS
A seven member Caucasian French family with two corneal intraepithelial dyskeratosis affected individuals (6-year-old proband and his mother) was ascertained. The proband presented with bilateral complete corneal opacification and dyskeratosis. Palmoplantar hyperkeratosis and laryngeal dyskeratosis were associated with the phenotype. Histopathology studies of cornea and vocal cord biopsies showed dyskeratotic keratinisation. Quantitative PCR ruled out 4q35 duplication, classically described in HBID cases. Next generation sequencing with mean coverage of 50× using the Illumina Hi Seq and whole exome capture processing was performed. Sequence reads were aligned, and screened for single nucleotide variants and insertion/deletion calls. In-house pipeline filtering analyses and comparisons with available databases were performed. A novel missense mutation M77T was discovered for the gene NLRP1 which maps to chromosome 17p13.2. This was a de novo mutation in the proband's mother, following segregation in the family, and not found in 738 control DNA samples. NLRP1 expression was determined in adult corneal epithelium. The amino acid change was found to destabilise significantly the protein structure.


CONCLUSIONS
We describe a new corneal intraepithelial dyskeratosis and how we identified its causative gene. The NLRP1 gene product is implicated in inflammation, autoimmune disorders, and caspase mediated apoptosis. NLRP1 polymorphisms are associated with various diseases.
Ophthalmology Department, Pavillon Dieulafoy, Place Baylac, 31057 Toulouse Cedex 9, France. vincesoler@yahoo.fr
Vincent José
VJ
Soler
Khanh-Nhat
KN
Tran-Viet
Stéphane D
SD
Galiacy
Vachiranee
V
Limviphuvadh
Thomas Patrick
TP
Klemm
Elizabeth
E
St Germain
Pierre R
PR
Fournié
Céline
C
Guillaud
Sebastian
S
Maurer-Stroh
Felicia
F
Hawthorne
Cyrielle
C
Suarez
Bernadette
B
Kantelip
Natalie A
NA
Afshari
Isabelle
I
Creveaux
Xiaoyan
X
Luo
Weihua
W
Meng
Patrick
P
Calvas
Myriam
M
Cassagne
Jean-Louis
JL
Arné
Steven G
SG
Rozen
François
F
Malecaze
Terri L
TL
Young
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D002648:Child; D060527:Corneal Keratocytes / Q000473:pathology; D019871:Dyskeratosis Congenita / Q000235:genetics* / Q000473:pathology; D019573:Epithelium, Corneal / Q000378:metabolism / Q000473:pathology*; D059472:Exome; D005260:Female; D005787:Gene Frequency; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D020125:Mutation, Missense; D000070576:NLR Proteins; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D000070576:NLR Proteins; C427903:NLRP1 protein, human