title: Rare FOXC1 variants in congenital glaucoma: identification of translation regulatory sequences.
abstract: Primary congenital glaucoma (PCG) is the cause of a significant proportion of inherited visual loss in children, but the underlying mechanism is poorly understood. In this study, we assessed the relationship between PCG and FOXC1 variants by Sanger sequencing the proximal promoter and transcribed sequence of FOXC1 from a cohort of 133 PCG families with no known CYP1B1 or MYOC mutations. The pathogenicity of the identified variants was evaluated by functional analyses. Ten patients (7.5%) with no family history of glaucoma carried five different rare heterozygous FOXC1 variants with both increased (rs77888940:C>G, c.-429C>G, rs730882054:c.1134_144del(CGGCGGCGCGG), p.(G380Rfs*144) and rs35717904:A>T, c.*734A>T) and decreased (rs185790394: C>T, c.-244C>T and rs79691946:C>T, p.(P297S)) transactivation, ranging from 50 to 180% of the wild-type activity. The five variants did not show monogenic segregation, and four of them were absent in a control group (n=233). To the best of our knowledge, one of these variants (p.(G380Rfs*144)) has not previously been described. One of the FOXC1 variant carriers (p.(P297S)) also coinherited a functionally altered rare PITX2 heterozygous variant (rs6533526:C>T, c.*454C>T). Bioinformatics and functional analyses provided novel information on three of these variants. c.-429C>G potentially disrupts a consensus sequence for a terminal oligopyrimidine tract, whereas c.-244C>T may alter the RNA secondary structure in the 5'-untranslated region (UTR) that affects mRNA translation. In addition, p.(G380Rfs*144) led to increased protein stability. In summary, these data reveal the presence of translation regulatory sequences in the UTRs of FOXC1 and provide evidence for a possible role of rare FOXC1 variants as modifying factors of goniodysgenesis in PCG.
authors.affiliation: Área de Genética, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, Spain.|Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Medina-Trillo
authors.affiliation: Área de Genética, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, Spain.|Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: José-Daniel
authors.initials: JD
authors.lastname: Aroca-Aguilar
authors.affiliation: Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.|Servicio de Oftalmología, Hospital San Carlos, SPAIN/Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Carmen-Dora
authors.initials: CD
authors.lastname: Méndez-Hernández
authors.affiliation: Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.|Servicio de Oftalmología, Hospital San Carlos, SPAIN/Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Morales
authors.affiliation: Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.|Servicio de Oftalmología, Hospital San Carlos, SPAIN/Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain.|Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Maite
authors.initials: M
authors.lastname: García-Antón
authors.affiliation: Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.|Servicio de Oftalmología, Hospital San Carlos, SPAIN/Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Julián
authors.initials: J
authors.lastname: García-Feijoo
authors.affiliation: Área de Genética, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, Spain.|Cooperative Research Network on Age-Related Ocular Pathology, Visual and Life Quality, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Escribano
mesh_terms: D020121:5' Untranslated Regions; D016022:Case-Control Studies; D002675:Child, Preschool; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics* / Q000378:metabolism; D005901:Glaucoma / Q000151:congenital* / Q000235:genetics; D057809:HEK293 Cells; D006579:Heterozygote; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D020641:Polymorphism, Single Nucleotide; D055550:Protein Stability; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D000097577:Homeobox Protein PITX2
chemical_list: D020121:5' Untranslated Regions; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C112743:FOXC1 protein, human