Lenz microphthalmia is inherited in an X-linked recessive pattern and comprises microphthalmia, mental retardation, and skeletal and other anomalies. Two loci associated with this syndrome, MAA (microphthalmia with associated anomalies) and MAA2, are situated respectively at Xq27-q28 (refs. 1,2) and Xp11.4-p21.2 (ref. 3). We identified a substitution, nt 254C→T; P85L, in BCOR (encoding BCL-6-interacting corepressor, BCOR 4 ) in affected males from the family with Lenz syndrome previously used to identify the MAA2 locus 3 . Oculofaciocardiodental syndrome (OFCD; OMIM 300166) is inherited in an X-linked dominant pattern with presumed male lethality and comprises microphthalmia, congenital cataracts, radiculomegaly, and cardiac and digital abnormalities. Given their phenotypic overlap, we proposed that OFCD and MAA2-associated Lenz microphthalmia were allelic, and we found different frameshift, deletion and nonsense mutations in BCOR in seven families affected with OFCD. Like wild-type BCOR, BCOR P85L and an OFCDmutant form of BCOR can interact with BCL-6 and efficiently repress transcription. This indicates that these syndromes are likely to result from defects in alternative functions of BCOR, such as interactions with transcriptional partners other than BCL-6. We cloned the zebrafish (Danio rerio) ortholog of BCOR and found that knock-down of this ortholog caused developmental perturbations of the eye, skeleton and central nervous system consistent with the human syndromes, confirming that BCOR is a key transcriptional regulator during early embryogenesis.We had previously localized MAA2 to a 10-Mb candidate region of Xp 3 . To identify the gene, we narrowed this region by excluding regions deleted in males with Xp deletions but without microphthalmia. Coriell cell line GM07947 is from a male with Duchenne muscular dystrophy, chronic granulomatous disease, McLeod phenotype and retinitis pigmentosa without microphthalmia 5 . Sequence-tagged site (STS) mapping confirmed previous data and oriented it to current genome maps. The deletion extended from DMD (telomeric) to between RPGR and OTC (centromeric; Fig. 1). The Coriell cell line GM10283 excluded two genes telomeric to DMD. This narrowed the critical region to ∼5 Mb, including 12 identified genes not known to be mutated in humans. One of these, DDX3, has an active Y homolog, and we therefore considered it unlikely to underlie a disorder with X-linked recessive inheritance. We sequenced the remaining 11 genes in members of the family in which MAA2 was originally identified. Ten of these genes showed no alterations, but we identified a missense change (nt 254C→T) in BCOR 4 that co-segregated with the disease phenotype (lod score of 2.46, above the threshold of 2.0 for X linkage 3 ). The corresponding residue of human BCOR, Pro85, is conserved in mouse, rat, chicken and pufferfish (Fig. 2), and we did not detect the nt 254C→T mutation among >450 control chromosomes. X-inactivation studies of peripheral blood leukocytes in two carriers of the mutation showed no ske...

The Perinatal Quality Foundation and the American College of Medical Genetics and Genomics, in association with the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the National Society of Genetic Counselors, have collaborated to provide education for clinicians and laboratories regarding the use of expanded genetic carrier screening in reproductive medicine. This statement does not replace current screening guidelines, which are published by individual organizations to direct the practice of their constituents. As organizations develop practice guidelines for expanded carrier screening, further direction is likely. The current statement demonstrates an approach for health care providers and laboratories who wish to or who are currently offering expanded carrier screening to their patients.