Expanding the spectrum of FOXC1 and PITX2 mutations and copy number changes in patients with anterior segment malformations.
OBJECTIVE
Anterior segment dysgenesis (ASD) comprises a heterogeneous group of developmental abnormalities that affect several structures of the anterior segment of the eye. The main purpose of this study was to assess the proportion of FOXC1 and PITX2 mutations and copy number changes in 80 probands with ASD.


METHODS
The patients were examined for FOXC1 and PITX2 copy number changes and mutations using MLPA (multiplex ligation-dependent probe amplification) and direct sequencing. Subsequently, the identified copy number changes were fine-mapped using high-resolution microarrays. In the remaining mutation-negative patients, sequencing of the FOXC1 andPITX2 3' untranslated regions (UTRs) and three other candidate genes (P32, PDP2, and FOXC2) was performed.


RESULTS
Thirteen FOXC1 and eight PITX2 mutations were identified, accounting for 26% (21/80) of the cases. In addition, six FOXC1 and five PITX2 deletions were found, explaining 14% (11/80) of the cases. The smallest FOXC1 and PITX2 deletions were 5.4 and 1.6 kb in size, respectively. Six patients carrying FOXC1 deletions presented with variable extraocular phenotypic features such as hearing defects (in 4/6) and mental retardation (in 2/6). No further genetic defects were found in the remaining mutation-negative patients.


CONCLUSIONS
FOXC1 and PITX2 genetic defects explain 40% of our large ASD cohort. The current spectrum of intragenic FOXC1 and PITX2 mutations was extended considerably, the identified copy number changes were fine mapped, the smallest FOXC1 and PITX2 deletions reported so far were identified, and the need for dedicated copy number screening of the FOXC1 and PITX2 genomic landscape was emphasized. This study is unique in that sequence and copy number changes were screened simultaneously in both genes.
D'haene
Barbara
B
Center for Medical Genetics, Department of Ophthalmology, Ghen University Hospital, Ghent, Belgium.
Meire
Françoise
F
Claerhout
Ilse
I
Kroes
Hester Y
HY
Plomp
Astrid
A
Arens
Yvonne H
YH
de Ravel
Thomy
T
Casteels
Ingele
I
De Jaegere
Sarah
S
Hooghe
Sally
S
Wuyts
Wim
W
van den Ende
Jenneke
J
Roulez
Françoise
F
Veenstra-Knol
Hermine E
HE
Oldenburg
Rogier A
RA
Giltay
Jacques
J
Verheij
Johanna B G M
JB
de Faber
Jan-Tjeerd
JT
Menten
Björn
B
De Paepe
Anne
A
Kestelyn
Philippe
P
Leroy
Bart P
BP
De Baere
Elfride
E
D020413:3' Untranslated Regions; D000293:Adolescent; D000328:Adult; D000869:Anterior Eye Segment / Q000002:abnormalities*; D002352:Carrier Proteins; D002648:Child; D002675:Child, Preschool; D005124:Eye Abnormalities / Q000235:genetics*; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics*; D018628:Gene Dosage / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D024101:Mitochondrial Proteins / Q000235:genetics; D009154:Mutation; D021141:Nucleic Acid Amplification Techniques; D016133:Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics*; D000097577:Homeobox Protein PITX2
D020413:3' Untranslated Regions; D002352:Carrier Proteins; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D024101:Mitochondrial Proteins; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C087299:C1QBP protein, human; C112743:FOXC1 protein, human