Transcript Genetic cause

Reproductive genetics,
Preimplantation genetic diagnosis
512 - Development
Sterility
is inability to conceive a child during one up to two
years of frequent intercourse without the use of
contraceptives
Femal infertility (dysfertility)
is inability to carry baby to term or give birth to
viable baby with sustained ability to conceive
Sterility
Primary – women have not been pregnant yet
Secondary - women were pregnant in the past
Many pregnancies terminated earlier, than we can prove
in conventional methods
Sterility covers 15-20% of couples
33% of male fertility disorder
25% female fertility disorder
20% fertility disorders both in the pair
15% of unknown cause
Abnormalities of chromosomes caused
30% of all abortions and 60% of early
abortions
Autosomal monosomy
Gardner, Sutherland:
Chromosome abnormalities
and genetic counseling,
1996
Thrombophilic mutations cause infertility
Mutations increasing the risk of clotting = thrombophilic mutations
Factor V Leiden R506Q mutation – in the gene for coagulation factor V. It
is manifested in homozygotes and heterozygotes = nature of AD mutations
Factor II Protrombin G20210A mutation cause higher level of
prothrombin. It is mutation of Caucasian race
mutation MTHFR = reductase methylenetetrahydrofolate
cause thrombophilic complications and neutral tube defects.
nature of AR mutations
Blood coagulation pathways in vivo
Sterility causes - men
Genetic causes
For the 50% of sterile men is cause a quantitative or qualitative
defect of spermatogenesis
Autoimmunity to own sperm
Epididymal Blockage
Coital problems
Vasectomy
Varicocele
An abnormal enlargement of the venous plexus
in the scrotum.
Investigative methods - men
Urine, immunological, hormonal, psychological examination, genetic
testing, biopsy epididymis/testis
Spermiogram - volume, viscosity, pH, concentration sperm :
20mil/ml – normospermia
Motility: moving quickly progressively........... a
slow-moving progressively………….. b
non-progressive moving ......... ……..c
immobile..................................……….d
Spermiogram
Computer analysis - quantitative evaluation of mobility,
analysis of the track and speed
Normozoospermia
Oligozoospermia less than 20mil/ml
Asthenozoospermia less than 50% a+b or less than 25% a
type
Teratozoospermia less than 30% morphologically normal
Azoospermia absence of sperm cells
Aspermie absence of ejaculate
Genetic cause - men
An aneuploidy of X, Y, 21, 8, 18 chromosome is observed in
sperms of the 70% of sterile men
Chromosomal aberrations
Marker chromosome
Inversion, ring, deletion of Y chromosome
Reciprocal translocation Y - autosome
It was proved an increased incidence of abortions in the (woman) partner
of carrier of balanced form of translocation
Gene defects of Y chromosome
Azoospermia factor AZF (AZFa, AZFb, AZFc) = genes in Yq12
and in Yq11 affected by mutations - deletions, microdeletions.
Microdeletions are cause for 3,77% of sterile men and for 15,63% of
azoospermic men
Gene mutation
Cystic fibrosis – 95% men with CF are sterile. 20% of
asoospermic men suffer form CF
Syndromes
Klinefelter's syndrome
Syndrome XYY- both fertile and sterile
Women pseudohermafroditismus – 46 XX, translocation
chromosome Y or the part (SRY gene) to another chromosome
Androgen insensitivity syndrome
complete - testicular feminization in 40% of men with
oligospermia and azoospermia
incomplete androgen resistance
- XR hypospadias, cryptorchidism, micropenis
Kartagener syndrome AR
hypospadia
Investigative methods - women
Examination of passable fallopian tube, hormonal, immunological,
psychological examination
Ovulation: progesterone, basal temperature, endometrial sample
examination, ultrasound examination
Genetic: karyotype, fluorescence hybridization in situ
Sterility causes - women
Genetic causes
Tubal blockage or damage
Endometriosis - the presence of uterine mucosa in
reproductive tissues
Hormonal problems
Too thick cervical mucus
Immunological rejection of sperm
Problems with zygote implantation
Premature menopause
Genetic - syndromes
Turner syndrome - karyotype 45 X0, deletions X (Xp), mosaic forms of
syndrome (50%). Woman with isochromosome (women with i Xq) are fertile.
Karyotype 47, XXX
Syndrome of polycystic ovarian
Kallman syndrome - reduced function of glands producing sex
hormones (absence of GnRH)
Chromosomal aberration
Polyploidy, aneuploidy in gametes especially of autosomes, reciprocal and
Robertsonian translocation, Inversions, Marker chromosomes,
Microdeletion syndromes
Disorders of gonadal development - Autosomal and X-
linked gene affected by mutations, which cause gonadal
dysgenesis, hypogonadotropic hypogonadism
- hormonal cause
- mutation or aberation of SRY region
- mutation of gene encoding DAX1 protein, which acts against
the SRY product
Complex structural rearrangement of chromosomes 3, 8, 10 – FISH,
balanced form of karyotype in mother
Microdeletion syndroms
Current Protocols in Human Genetics Online
Copyright © 2003 John Wiley & Sons, Inc.
Postcoital test (Sims-Huhn) = test of
lifetime of sperm cells: 6 - 24 hod after the
intercourse is taken a sample of mucus from the
cervix (uterus)
More than 6 progressively moving sperms is
normal situation
Sterility treatment
Women - pharmacological treatment of ovulation disorders
Surgical treatment of tubal abnormalities
Surgically or pharmacological treatment of Endometriosis
Men - sperm changes - change in lifestyle!!
pharmacological treatment
Surgical treatment of varicocele or occlusion
Pharmacological treatment of endocrine or immunological
causes
Assisted reproduction - methods
IUI intrauterine insemination
IVF in vitro fertilization
ICSI intracytoplazmatic injection of sperm
AH - assisted hatching
ET – embryotransfer
TESE - testicular extraction of sperm
MESA - biopsy of epididymis
PZD - parcial disection of zona pellucida
SUZI - subzonal insemination - location of 1 to 7 sperm in perivitelinne space
Kryokonzervation of gametes, embryos
TESE, MESA
PZD
SUZI
ICSI
Embryotransfer
IUI
IUI artificial insemination
after induction of ovulation
are obtained and washed sperm cells
of the husband or donor and are transferred into the uterus
using a special catheter
indications: women with hormonal disorders, men with the
inability to ejaculate into vaginy
In vitro fertilization – IVF
= pharmacological stimulation of ovulation,
the collection of several oocytes, cultivation in
laboratory conditions with sperms, transfer of
embryos into uterus
indications: blockage of fallopian tubes,
endometriosis, unknown cause
Intracytoplazmatic injection of sperm
- ICSI
= pharmacological stimulation, micromanipulatory
insemination, transfer of embryos into the uterus
indications: defects in sperm, oligoasthenospermia,
azoospermia (MESA, TESE), unsuccessful IVF
Assisted hatching
= disruption of zona pellucida,
which contributes to increase the probability of
embryo implantation in the uterine mucosa
Indication: an unsuccessful pregnancy with IVF
or in women over 35 years
It is provided by chemical, mechanical, laser way.
Preimplantation genetic
diagnostics - PGD
Molecular - genetic, molecular - cytogenetic examination of
gametes, polar bodies, blastomeres, blastocyst
Benefits = Reduced risk of spontaneous abortions
Reduced number of children affected by chrom. aberrations
Reduced number of affected children with a genetic mutation
(AR, XR)
Increased successful rate of implantation of embrya,
of assisted reproduction methods
Preconceptional genetic diagnostics
Biopsy of polar bodies –
Disadvantage:
small amount of material
DNA analysis of genome of mother only.
Risk of crossing-over, which leads to a false pos
and false neg results.
Preimplantation genetic diagnostics
Biopsy of blastomere
1-2 blastomeres are examined in 2-3 day after in vitro
fertilization method: it is embryo of 6-10 blastomers
Disadvantages:
It is amplified the information only from one allele, thus
there is the risk of mozaicism (1blastomer)
Advantages:
analysis of father and mother genome
Biopsy of blastocyst for fertile couples
advantages: analysis of the genome of father and mother,
analysis of multiple cells of trofoblast,
- 3-4 cells in 5. day after in vitro fertlilization method
The optimal combination is an examination of both
polar bodies with biopsy of blastomere and with the
control of conclusions of prenatal diagnostics in II
trimester
Indication - PCR versus FISH
PCR: AD gene mutations, AR gene mutations, gene
mutations of male sterility
FISH: aneuploidy, presence of translocation in
one of parents, identification of sex in X-linked
inherited diseases
Monogenic hereditary disease
Familial adenomatous polyposis of the colon - AD
Deficiency of alpha-1-antitrypsin - AR
Cystic fibrosis - AR
Duchenne muscular dystrophy - XR
Fragile X chromosome syndrome - XR
Haemophilia A, B - XR
Huntington's disease - AD
Marfan Syndrome - AD
Sickle cell anemia - AR
Tay-Sachs disease - AR
Thalassemia AR ............ mediterranean
FISH
MultiVysion (13,18,21,X,Y)
MultiVysion (13,16,18,21,22, X,Y,15,17)
(13,16,18,21,22)
Z materiálu Dr. Jenčíkové - GENNET
Trisomie
13,18,21,X
Z materiálu Dr. Jenčíkové - GENNET
Thank you for attention
http://www.advancedfertility.com/hatching.htm
Human Genetics, Ricki Lewis, chapter 21:
Reproductive technologies