Biomedical subjects

Lucia Brown

Publications and source records attributed to Lucia Brown.

3 recordsLinked to original sources

PubMed2006

Validation of QF-PCR for prenatal aneuploidy screening in the United States.

OBJECTIVE: QF-PCR is an inexpensive and reliable method for aneuploidy screening; however, despite its obvious advantages, it is not in routine use in the United States. Our objective in the present study was to validate QF-PCR as a means for prenatal aneuploidy screening in our institution. METHODS: A QF-PCR assay using 15 primer pairs located on chromosomes 13, 18, 21 X and Y was established for aneuploidy screening. Amniotic fluid (AF) and chorionic villus sampling (CVS) samples consisting only of the cells recovered from the plasticware discarded by our institutional cytogenetics laboratory were collected and DNA was prepared by a simple and inexpensive microwave procedure. QF-PCR was then performed and interpreted using established criteria. RESULTS: 687 consecutive prenatal samples were screened in a blinded prospective manner, and results were compared to those obtained by conventional cytogenetics. 100% of autosomal trisomies were detected, and there were zero false positives. A single case each of XXY and 45X were missed. CONCLUSIONS: QF-PCR for prenatal aneuploidy screening was validated in our laboratory and has now been approved by the New York State Clinical Laboratory Evaluation Program. We propose a simple protocol for integrating QF-PCR into the normal cytogenetics laboratory workflow.

Amniotic Fluid↗

PubMed2004

In vitro analysis of partial loss-of-function ZIC2 mutations in holoprosencephaly: alanine tract expansion modulates DNA binding and transactivation.

Heterozygous loss-of-function mutations in ZIC2 result in the severe brain malformation known as holoprosencephaly (HPE), indicating that forebrain development is exquisitely sensitive to the activity of this poorly understood transcription factor. To identify the regions of ZIC2 that are essential for activity, we have assessed the ability of a variety of ZIC2 mutant proteins to function in in vitro assays. Two sources of information were used to design relevant mutations. First, phenotype producing mutations in human and in mouse ZIC2 were mimicked and secondly, a comparative sequence analysis of the C-terminal was carried out. Analysis of these mutations suggests that either a decrease or an increase in ZIC2 mediated transcriptional activity can produce a forebrain phenotype. In addition, the analysis reveals that the C-terminal of ZIC2 contains both activation and repression domains. This region of ZIC2 contains an alanine-tract, and expansion of this domain is associated with HPE. In vitro analysis of proteins with alterations in alanine-tract length illustrates that the C-terminal alanine-tract of ZIC2 influences the strength of DNA binding and alters transcriptional activity in a promoter-specific manner. This finding provides a possible mechanism by which alanine-tract expansion mutations could alter the function of other transcription factors.

Alanine↗

PubMed2003

Zic2 patterns binocular vision by specifying the uncrossed retinal projection.

During CNS development, combinatorial expression of transcription factors controls neuronal subtype identity and subsequent axonal trajectory. Regulatory genes designating the routing of retinal ganglion cell (RGC) axons at the optic chiasm to the appropriate hemisphere, a pattern critical for proper binocular vision, have not been identified. Here, we show that the zinc finger transcription factor Zic2, a vertebrate homolog of the Drosophila gene odd-paired, is expressed in RGCs with an uncrossed trajectory during the period when this subpopulation grows from the ventrotemporal retina toward the optic chiasm. Loss- and gain-of-function analyses indicate that Zic2 is necessary and sufficient to regulate RGC axon repulsion by cues at the optic chiasm midline. Moreover, Zic2 expression reflects the extent of binocularity in different species, suggesting that Zic2 is an evolutionarily conserved determinant of RGCs that project ipsilaterally. These data provide evidence for transcriptional coding of axon pathfinding at the midline.

Animals↗