Aneuploides & QF-PCR Flashcards
QF-PCR
Quantity Fluorescence-PCR:
- newborn screening for aneuploidies
- different coloured fluorophores attached to different STR
Aneuploidy
Gain or loss of a chromosome
Monosomy
Loss of a chromosome
Disomy
Two copies of a chromosome (normal for humans)
Trisomy
Three copies of a chromosome
Non-disjunction
- failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division
- usually resulting in an abnormal distribution of chromosomes in the daughter nuclei
Turner Syndrome
- Monosomy X0
- karyotype: 45, X
- viable, 1/2500 girls
- **webbed neck, loss of ovarian function **
Klinefelter Syndrome
- Karyotype: 47, XXY
- Viable, 1/650 boys
- small testes/ penis, breast growth
Trisomy X
- Karyotype: 47, XXX
- 1/1000 girls; most common X chromosome aneuploidy
- taller than average females, developmental delays
Jacob syndrome
- Karyotype: 47, XYY
- viable, 1/1000 boys
- tall, enlarged head, learning disability
Patau Syndrome
- Trisomy 13
- Karyotype: 47, XX+13 or 47, XY+13
-
cleft palate, extra digits, heart and CNS defects
= 1/16,000
3 Trisomies that are most compatible with life
Patau Syndrome (trisomy 13) - least common
Edwards Syndrome (trisomy 18)
Down Syndrome (trisomy 21) - most common
Edwards Syndrome
Trisomy 18
- Karyotype: 47,XX+18 or 47, XY+18
- small, feeding and breathing problems
- 1/ 5,000
Downs Syndrome
- Trisomy 21
- Karyotype: 47,XX+21 or 47, XY+21
- characteristic craniofacial abnormality, childhood leukemia, early onset Alzheimer’s disease
- 1/ 700
How can STR be used for paternity ?
Mom: 12 TCTA allele/ 7 TCTA allele
Dad: 11 TCTA allele/ 9 TCTA allele
=
Child: 7 TCTA allele/ 9 TCTA allele
- should have one allele from both parents (with characteristic STR)
