X-linked dominant inheritance with lethality in hemizygous males is a rare mode of inheritance. The three best-known disorders which seem to be inherited in this way, are incontinentia pigmenti (IP) Bloch-Sulzberger, oral-facial-digital I (OFD I) syndrome, and focal dermal hypoplasia (FDH syndrome, Goltz syndrome). It is the purpose of this article to give a review of the clinical and genetic aspects of the above-mentioned diseases and to add those disorders in which this mode of inheritance is discussed. These disorders are: X-linked chondrodysplasia punctata (CP), cervico-oculo-acusticus syndrome (Wildervanck syndrome, COA), congenital cataract with microcornea or slight microphthalmia, muscular dystrophy--hemizygous lethal, partial lipodystrophy with lipatrophic diabetes and hyperlipidemia, Aicardi syndrome, coxo-auricular syndrome, and Johanson-Blizzard syndrome. OTC deficiency is included in the study, although there is no lethality in utero, only in the neonatal period. A critical evaluation of the current literature is carried out.

A human aniridia candidate (AN) gene on chromosome 11p13 has been cloned and characterized. The AN gene is the second cloned gene of the contiguous genes syndrome WAGR (Wilms' tumor, aniridia, genitourinary malformations, mental retardation) on chromosome 11p13, WT1 being the first gene cloned. Knowledge about the position of the AN and WT1 genes on the map of 11p13 makes the risk assessment for Wilms' tumor development in AN patients possible. In this study, we analyzed familial and sporadic aniridia patients for deletions in 11p13 by cytogenetic analyses, in situ hybridization, and pulsed field gel electrophoresis (PFGE). Cytogenetically visible deletions were found in 3/11 sporadic AN cases and in one AN/WT patient, and submicroscopic deletions were identified in two sporadic AN/WT patients and in 1/9 AN families. The exact extent of the deletions was determined with PFGE and, as a result, we could delineate the risk for Wilms' tumor development. Future analyses of specific deletion endpoints in individual AN cases with the 11p13 deletion should result in a more precise risk assessment for these patients.

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