European Human Genetics Conference 2007 June 16 – 19, 2007 ...

Molecular and biochemical basis of disease
P0702. Identification of reduced copy number of DAZ genes in a
group of Romanian idiopathic infertile men
R. Cocoş 1 , F. Raicu 2,3 , D. Neagoş 1 ;
1 Carol Davila”University of Medicine and Pharmacy, Bucharest, Romania, 2 Department
of Clinical Sciences and Imaging G. D’Annunzio University Foundation
Chieti-Pescara, Chieti, Italy, 3 Aging Research Center (CESI) G’ D’Annunzio
University Foundation Chieti, Chieti, Italy.
Male infertility is now a major reproductive health problem and the field
has attracted considerable attention from scientists and clinicians. Approximately
15% of men with idiopathic infertility have microdeletions
of the Y chromosome. The DAZ genes are candidate fertility factors
that lie within the human Y chromosome’s AZFc region. AZFc deletions
including all four members of DAZ gene family represent the most frequent
molecular cause of spermatogenic impairment. Besides complete
DAZ family deletions, partial deletions are also associated with
impaired spermatogenesis. PCR digest assay is one of the methods
that can distinguish among the different copies of the four DAZ genes
using subtle sequence differences located in introns and among members
of the DAZ genes. These differences are termed sequence family
variants (SFVs). We use this approach to determine the exact number
of genes in a group of idiopathic infertile men. We screened the genomic
DNA of 54 infertile males and 40 healthy fertile controls. Using
PCR digest assay we determined that 2 patients of 54 had a deletion
of two copies of DAZ (DAZ1 and DAZ2) showing that these deletions
can be the cause for spermatogenic failure No deletions were detected
in the control group. Initial molecular investigation by multiplex PCR
was conducted according to European guidelines for the molecular
diagnosis of Y chromosome microdeletions and all patients presented
no deletions for DAZ genes. Our study, the first in a Romanian population,
suggest a cause and effect relationship between partial DAZ gene
microdeletion and idiopathic infertility.
P0703. Growth factor-induced stem cell differentiation into inner
ear hair cell precursors on two- and three- dimensional surfaces
M. Peverelli 1,2 , H. Dahl 1,3 , A. J. O’Connor 4 , A. Robertson 1 , M. G. de Silva 1,5 ;
1 Murdoch Childrens Research Institute, Royal Children’s Hospital, Melbourne,
Australia, 2 Department of Paediatrics, University of Melbourne, Melbourne,
Australia, 3 Department of Paediatrics, University of Melbourne, Australia, 4 Department
of Chemical and Biomolecular Engineering, University of Melbourne,
Melbourne, Australia, 5 Department of Chemical and Biomolecular Engineering,
University of Melbourne, Melbourne, Austria.
Sensorieural hearing loss is associated with damage and loss of inner
ear hair cells. Although hair cells within the avian and reptile cochlea
are able to undergo spontaneous regeneration following damage to
the auditory system, mammalian hair cells do not possess this ability.
The availability of stem cells has presented the opportunity to establish
therapies based on replacing or regenerating damaged cells within the
inner ear. To explore these therapies it is essential to understand the
normal hair cell differentiation pathway. Our investigations focused on
the ability of mouse embryonic stem (ES) cells to commit to hair cell
lineage by identifying key cytokines involved in hair cell determination.
ES cells were differentiated into embryoid and neurectodermal
embryoid bodies and treated with different combinations of cytokines.
Commitment to hair cell lineage was assessed by expression of hair
cell markers via semi-quantitative RT-PCR and flow cytometry. Since
terminally differentiated hair cells were not generated with high efficiency
on 2D tissue culture plates, a tissue engineering approach was
undertaken using biodegradable polymers. The copolymer poly(lacticco-glyoclic
acid) PLGA was formed into 3D constructs using thermally
induced phase separation. Morphology of polymers mimicked key
architectural features of the inner ear sensory epithelium to encourage
growth and differentiation of cells into inner ear types. Taking the
most promising culture conditions from 2D work, partially differentiated
ES cells were successfully grown on PLGA scaffolds with cells coexpressing
hair cell markers. These approaches provide encouraging
results for the possibility of differentiating inner ear hair cells in vitro.
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P0704. Diamond-Blackfan Anemia - Haploinsuffiency or RNA
binding?
J. Schuster, J. Badhai, A. Fröjmark, E. Davey, P. Frisk, N. Dahl;
University Uppsala, Uppsala, Sweden.
Diamond-Blackfan-Anemia (DBA) is a congenital disorder with absence/decrease
of erythroid precursors in the bone marrow. ~25% of
DBA patients carry a mutation in the ribosomal protein S19 (RPS19),
~2% in the RPS24 gene. The molecular basis underlying DBA is yet
unclear.
We investigated fibroblast from patients with RPS19 and RPS24 mutations
and found a significantly prolonged (P