BACKGROUND: Macular corneal dystrophy (MCD) is an inherited autosomal recessive disorder that has been subdivided into two primary immunophenotypes, MCD types I and II. The MCD type I gene has been localised previously to chromosome 16q22 and suggestive evidence provided that MCD type II gene is also linked to this region. Here an unusual family is reported where both MCD types I and II are found in a single sibship. METHODS: Immunoreactivity to an anti-keratan sulphate monoclonal antibody (5-D-4) was evaluated in patients' serum and in corneal tissue obtained at keratoplasty. Chromosomal haplotypes were constructed using microsatellite repeat markers spanning the region of the MCD type I locus. RESULTS: Immunological studies demonstrated that two of the affected siblings have MCD type II while one has MCD type I. Haplotype analysis suggests that all three affected sibs inherited one identical parental haplotype. However, the two MCD types differ in their alternative chromosome with both MCD type II children sharing an identical haplotype, different from their MCD type I sibling. CONCLUSION: The findings in this study support the hypothesis that the genes for MCD types I and II co-localise to the same region of chromosome 16 and are likely to be due to allelic manifestations of the same abnormal gene.
BACKGROUND:Macular corneal dystrophy (MCD) is an inherited autosomal recessive disorder that has been subdivided into two primary immunophenotypes, MCD types I and II. The MCD type I gene has been localised previously to chromosome 16q22 and suggestive evidence provided that MCD type II gene is also linked to this region. Here an unusual family is reported where both MCD types I and II are found in a single sibship. METHODS: Immunoreactivity to an anti-keratan sulphate monoclonal antibody (5-D-4) was evaluated in patients' serum and in corneal tissue obtained at keratoplasty. Chromosomal haplotypes were constructed using microsatellite repeat markers spanning the region of the MCD type I locus. RESULTS: Immunological studies demonstrated that two of the affected siblings have MCD type II while one has MCD type I. Haplotype analysis suggests that all three affected sibs inherited one identical parental haplotype. However, the two MCD types differ in their alternative chromosome with both MCD type IIchildren sharing an identical haplotype, different from their MCD type I sibling. CONCLUSION: The findings in this study support the hypothesis that the genes for MCD types I and II co-localise to the same region of chromosome 16 and are likely to be due to allelic manifestations of the same abnormal gene.
Authors: M A Pericak-Vance; L H Yamaoka; C S Haynes; M C Speer; J L Haines; P C Gaskell; W Y Hung; C M Clark; A L Heyman; J A Trofatter Journal: Exp Neurol Date: 1988-12 Impact factor: 5.330
Authors: H S Scott; T Litjens; P V Nelson; P R Thompson; D A Brooks; J J Hopwood; C P Morris Journal: Am J Hum Genet Date: 1993-11 Impact factor: 11.025
Authors: E J Thonar; M E Lenz; G K Klintworth; B Caterson; L M Pachman; P Glickman; R Katz; J Huff; K E Kuettner Journal: Arthritis Rheum Date: 1985-12
Authors: G K Klintworth; R Meyer; R Dennis; A T Hewitt; E L Stock; M E Lenz; J R Hassell; W J Stark; K E Kuettner; E J Thonar Journal: Ophthalmic Paediatr Genet Date: 1986-12
Authors: T C Gilliam; L M Brzustowicz; L H Castilla; T Lehner; G K Penchaszadeh; R J Daniels; B C Byth; J Knowles; J E Hislop; Y Shapira Journal: Nature Date: 1990-06-28 Impact factor: 49.962
Authors: E J Thonar; R F Meyer; R F Dennis; M E Lenz; B Maldonado; J R Hassell; A T Hewitt; W J Stark; E L Stock; K E Kuettner Journal: Am J Ophthalmol Date: 1986-11-15 Impact factor: 5.258