| Congenital microphthalmia is a developmental ocular malformation characterized by a small eye, shorted axial length, narrow palpebral fissure, small fossa orbitalis. Congenital microphthalmia can result in severe visual consequences. Congenital microphthalmia have different clinical manifestations, ranging from small size of a single eye to complete bilateral absence of ocular tissues. Nanophthalmos is a relatively rare condition characterized by a small eye in the absence of any systemic abnormalities. Congenital microphthalmia is frequently associated with other ocular abnormalities, including anterior segment dysgenesis, cataract, chorioretinal coloboma, retinal dysplasia and optic-nerve coloboma. Anophthalmos is extreme form of microphthalmos. Although most cases of microphthalmia are sporadic, a few family with autosomal dominant, autosomal recessive, and X-linked recessive inheritance of the trait have been reported. The associated genes for congenital microphthalmia have been mapped on several loci: MITF S0X2 PAX6 MCOP NN02 and so on. The additional locus remains to be identificated.Research had been performed on a Chinese pedigree of autosomal dominantcongenital microphthalmia through genescan and linkage analysis to investigate the location of the disease-causing gene associated with the family. We had identified a five generations pedigree of autosomal dominant congenital microphthalmia came from zhejiang province. Genomic DNA was extracted from peripheral blood samples of 8 affected and 11 unaffected family members. According to five loci reported previously (MITF, SOX2, PAX6, MCOP and NN02), 14 microsatellite markers on chromosome 3, 11 14 15 were used as genetic markers and were amplified by PCR (polymerase chain reaction) with fluorescence labeled primers. Genome screening and genotyping were conducted by ABI377 DNA sequencer in this microphthalmia family and linkage analysis was performed with LINKAGE software package.The LOD scores less than - 2 at all 14 microsatellite markers indicated that there was no linkage between these markers and the disease locus in this microphthalmia family. The gene responsible for microphthalmia in this family is distinct from the five reported loci. Microphthalmia in this family may be resulted from defects in a new developmental gene which is essential in eye development. |
