title: Mapping of a novel type III variant of Knobloch syndrome (KNO3) to chromosome 17q11.2.
abstract: Knobloch syndrome (KNO) is an autosomal recessive disorder characterized by ocular abnormalities (myopia and retinal detachment) and occipital encephalocele. The syndrome is clinically and genetically heterogeneous (KNO1, KNO2). Previously germline mutations in COL18A1 (21q22.3) were detected in some families, but in other kindreds linkage to COL18A1 was excluded. We ascertained a large consanguineous family with high myopia, vitreoretinal degeneration and occipital scalp defect with autosomal recessive mode of inheritance. Due to the overlapping clinical presentation of this family with Knobloch syndrome we propose this phenotype as a type III variant of KS (KNO3). A genome wide linkage study using microsatellite markers at 10-20 cM interval revealed linkage to 17q11.2 with a maximum LOD scores 3.40 (theta = 0.00) for markers D17S1307 and D17S1166. Fine mapping defined a 2.67 cM disease region between D17S1307 and D17S798. Mutation analysis of three candidate genes (UNC119, MYO1D, and RAB11FIP4) within the disease region did not identify any disease-associated mutation in affected individuals.
authors.affiliation: Biomedical and Genetic Engineering Division, Dr. A. Q. Khan Research Laboratories, Islamabad, Pakistan.
authors.forename: Shagufta
authors.initials: S
authors.lastname: Khaliq
authors.forename: Aiysha
authors.initials: A
authors.lastname: Abid
authors.forename: Dominick R A
authors.initials: DR
authors.lastname: White
authors.forename: Colin A
authors.initials: CA
authors.lastname: Johnson
authors.forename: Muhammad
authors.initials: M
authors.lastname: Ismail
authors.forename: Ayesha
authors.initials: A
authors.lastname: Khan
authors.forename: Qasim
authors.initials: Q
authors.lastname: Ayub
authors.forename: Salma
authors.initials: S
authors.lastname: Sultana
authors.forename: Eamonn R
authors.initials: ER
authors.lastname: Maher
authors.forename: Syed Qasim
authors.initials: SQ
authors.lastname: Mehdi
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002874:Chromosome Mapping; D002886:Chromosomes, Human, Pair 17; D004677:Encephalocele / Q000235:genetics; D005260:Female; D005808:Genes, Recessive; D005819:Genetic Markers; D006801:Humans; D008126:Lod Score; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D009154:Mutation; D009216:Myopia / Q000235:genetics; D010375:Pedigree; D012163:Retinal Detachment / Q000235:genetics; D013577:Syndrome
chemical_list: D005819:Genetic Markers