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Bart P. Leroy, Sarah Vergult, Ilse Claerhout, Björn Menten; Microphthalmia with Linear Skin Defects in a Mother and Daughter due to a Submicroscopic Xp22.2 Deletion. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1545.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the phenotype of a mother and daughter with the Microphthalmia with Linear Skin Defects syndrome (MLS or MIDAS; OMIM #309801), including retinal abnormalities, which have not yet been described. MLS is a severe, rare X-linked dominant disorder with male lethality due to mutations in the HCCS gene encoding Holocytochrome c synthase.
A 42 y/o woman (patient 1) and her 9 y/o daughter (patient 2) were referred for ophthalmological evaluation because of unilateral microphthalmia. Both underwent a complete ophthalmological examination, including extensive imaging in both, and electroretinography in patient 1. Conventional karyotyping and micro-array comparative genome hybridisation (CGH) was performed in both.
Patient 1 had her left eye (LE) enucleated at an early age because of severe microphthalmia. The anterior segment of her right eye (RE) was normal, whereas fundoscopy, fluorescein angiography and optical coherence tomography showed patches of outer retinal abnormalities with white dots and pigment epithelial alterations temporal from the macula and into the whole periphery. The ERG showed abnormal rod and low normal cone function.The RE of patient 2 is microphthalmic. The right cornea showed incomplete stromal opacities in the central and temporal areas, in combination with endothelial abnormalities. The iris stroma was slightly hypoplastic, most pronounced in the inferior and temporal area. Fundoscopy showed no gross abnormalities in the microphthalmic RE. The left eye was entirely normal.Whereas patient 1 had scars consequent upon neonatal skin lesions typical of MLS, the skin of patient 2 was entirely normal.Karyotyping revealed a normal female karyotype (46,XX) in both patients. On array CGH analysis a submicroscopic deletion of 203-318 kb was detected on chromosome band Xp22.2 in both patients. The deletion includes the complete HCCS gene and part of the ARHGAP6 gene.
MLS can be caused by a submicroscopic deletion of Xp22.2 including the entire HCCS gene. The ocular phenotype is variable and can either be unilateral or very asymmetrical bilateral, and can include rod dysfunction. The skin lesions are not present in all patients.
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