2009 Vienna - European Society of Human Genetics

Cytogenetics
United States.
Recent advancements in our understanding of the structural complexity
within the human genome have created a need for finer scale
cytogenetic visualization of chromosomes. Since fluorescence in situ
hybridization (FISH) provides the necessary positional and visual understanding
of chromosomal architecture to complement other technologies
for the discovery and analysis of cytogenetic variation, we
set out to improve FISH performance through the introduction of oligonucleotide-based
DNA probes. Using chemically synthesized complex
libraries of oligonucleotides as templates for target regions identified
as being variant by array comparative genomic hybridization (aCGH),
we directed our probes only at the most informative elements within
these regions to achieve high specificity with maximum flexibility. Probe
generation involved a simple PCR amplification step, followed by the
introduction of fluorescent labels by chemical modification. The downstream
hybridization workflow closely resembles those widely used for
BAC-based FISH. Here, we report the robust and specific visualization
of six different regions that could not be readily assayed by traditional
BAC-based FISH previously, with our initial studies detecting regions
as small as 23 kb. One of these regions contained a known benign
copy number change near the telomere of chromosome 6 which appears
to be amplified in a non-homologous region of another chromosome.
Our results indicate that these chemically synthesized complex
library FISH probes will allow for structural characterization of abnormal
findings seen by high-resolution methods such as aCGH and DNA
sequencing and further advance our understanding of copy number
variation in the human genome.
P03.024
Genotoxicity of formaldehyde in human chromosomes
M. Pongsavee;
Faculty of Allied Health Sciences, Thammasat University, Rangsit Campus,
Patumthani, Thailand.
Formaldehyde is a clear, colorless, volatile liquid which has a pungent
odor and slightly irritating taste. It is useful for industry and medicine but
it is the forbidding material for the vegetable and seafood preservation.
When formaldehyde is accumulated in human body, it causes eyes
and skin irritation, suffocation, chest pain and death. The heparinized
blood from thirty healthy Thais were studied for the impact of formaldehyde
genotoxicity through human lymphocyte culture and G- banding
technic. The formaldehyde concentrations of 0.036, 0.072, 0.15, 0.3,
0.576, 0.8 and 1.152 mg/ml were used in this experiment. The results
showed that the numbers of metaphase chromosomes in the 0.036
and 0.072 mg/ml formaldehyde concentration groups were different
significantly comparing with the control group (P15 days of cleaning-up tasks at least four hours per
day) and non-exposed (NE) group. A total of 91 E and 46 NE fishermen
were studied. The collection of the samples was performed between
July 2004 and February 2005. Cytogenetic damage was determined by
structural chromosome alterations from peripheral blood lymphocytes.
For each subject, more than 25 karyotypes were examined using 72 h
cultures. Our results showed a positive association between frequency
of structural chromosome alterations and fuel exposure (196 structural
chromosome alterations in a total of 2448 karyotypes analyzed) vs NE
(33 /1285)(P