Embryology Flashcards
What is an issue with PB biopsy
Analysis of both PB is required to identify Meiosis 1 and 2 errors
ASRM and sart recommend how many embryos to transfer
Picture
Euploid= 1 for all
Other non tested= 1, 38-40=2, 41-42=3
Quality management(Qm) includes what
Qc, QA, QI and lab accreditation
QC
Quality control
Trained personnel
Instruments calibrated
Environment, media reagents
Execution of techniques
Safety manuals
Records
Procedure manuals
Corrective actions
Quality assurance qa
Monitor and evaluate quality of outcomes
Set thresholds
Kpis (critical indicators)
Why are sperm good to freeze
Smallest human cell with small volume and large surface area
Little cytoplasm
Contain less total intercellular water than other cells
Exist individually, good for dehydration
Sperm cryo temperature range where extra cellular ice formation occurs and induces extra cellular solid phase?
-5cā -15c
Super cool phase
Standards for sperm banking established by:
Guideline by?
American association of tissue banks aatb
ASRM
What causes numerical chromosome defects?
Nondisjunction- failure of homologus chromosomes to split during metaphase of meiosis
Klinefelters
XXY
Azospermic
Small testis
Sperm available through tese
Xyy males
Usually fertile
Aggressive behavior
XX males
Genotype female
Phenotype male
Small testis
X blocks meiosis =azospermic
Sertoli only phenotype no sperm to retrieve
Robertsonian translocation
Translocations b/t Acrocentric chromosomes (small too long bottom) long sections are translocated to other long section
Usually 13,14 14,15 13,21 or 21,22
Oligospermic
45 chromosomes
AZF spermatogenesis gene microdeletions
AZFc= have sperm
AZF a and b= sertoli only, no sperm
What is an aCGH
Array comparative genomic hybridization
Microarray recognizes unbalanced gains and losses, CNV( copy number variation) Fluorescence yellow= ok, green =gain, red=loss
Whole chromosome
Aneuploidy
Partial chromosome abnormalities
Translocations and deletions
Micro deletions and copy number variants (CNV)
Duplications/ deletions in regions of DNA
Point mutation
Sexual determination disorders
Gonads fail to form during development due to gene malfunction
Need WT1 and SF1 for gonadal ridge to form
SF1 loss =sex reversal in XY
SRY and SOX9=required for testis differentiation (bio potential gonad towards testis)
Nondisjunction (ND) vs Premature Seperation of Sister Chromatids (PSSC)
Maternal meiotic errors arise from both
PSSC- 90% maternal meiosis 1 erros result from this
ND- occurs at cross over
See picture
3 steps of PGT-A detection
DNA amplification
Detection
Analysis
Technology for 24 chromosome embryonic Aneuploidy screening
Comparative genomic hybridization (CGH)
Quantitative SNP array
QPCR
Nextgen
CGH
Comparative genome hybridization
Metaphase chromosome, whole gene amplification, dna hybridized to metephase spreads
PBs or embryonic bx dna, labeled with fluorophore (red or green)
Increased brightness=trisomy
Decreased=monosomy
Takes 12hrs-days long time
Quantitative SNP array
Whole genome amplification dna labeled with a fluorophore and each locus and copy number compared to other snps on the chip
Quantitative SNP array
Whole genome amplification dna labeled with a fluorophore and each locus and copy number compared to other snps on the chip
Good for microdeletions
ArrayCGH
CGH on a microarray
Not metaphase chromosomes, dna is hybridized with specific segments from each chromosome. Then measures at a specific segment of the chromosome and replicates each segment.
QPCR
Quantitation of the number of amplification cycles required to attain a reliably detectable signal for amplification at a specific locus
4 loci on each chromosome and measures in quads (24 chromosomes x 4 loci x 4 rxns)
384 reactions
Amplification and quantitation concurrent so is fast results
Taq polymerase
Next gen sequencing
Taq polymerase to amplify whole genome to create small fragments of dna- each fragment is sequenced and aligned based on sequence of nucleic acids with sequences from a database.
Segment being analyzed is a depth
More reads = trisomic
Under representation= monosomic
PGT-SR-
Balanced translocations detection
PGT-M
Single gene defects
For couples with a known risk for a particular genetic disorder
What maintains meiotic arrest Intra oocyte
cAMP and cGMP
