What
is Pre marital Screening
A premarital test is defined as a test in which couples
that are going to get married are tested for genetic,
infectious and blood transmitted diseases to prevent
any risk of transmitting any disease to their children.
Nowadays premarital testing is considered an important
issue, as a result of the increasing in the number
of children affected with genetic or blood transmitted
diseases.
Importance of Premarital Screening
Hereditary disease, specially or
specifically sickle cell disease and to a lesser extent
thalassemia, are present with a high prevalence in
Gulf and caused great suffering of the children. Since
the 1950s, Arab countries have made progress in some
health related aspects such as: infant mortality,
life expectancy, and access to health care. Data from
industrialized countries show that significant genetic
diseases or birth defects that may affect approximately
3% of all pregnancies, account for up to 30% of pediatric
hospital admissions, and cause about 50% of childhood
deaths. In addition, recessively inherited disorders
account for less than 20% of single gene disorders
and less than 5% of congenital and genetic diseases
(Alwan and Modell, 1997). On the other hand, genetic
and congenital disorders are responsible for a considerable
proportion of perinatal and neonatal mortalities in
Arab populations.
Considering the facts, recently premarital screening
has been made mandatory by the Ministry of Health,
UAE and all couples should go through the screening
process before getting married. The couples need to
provide certifcate stamped by the department of states
of premarital screening to the court to proceed with
the wedding.
Premarital screening mainly aimed at reducing the
number of children with inherited diseases. It is
a comprehensive group of tests for those who are planning
to get married and highly beneficial for the couples
who are under the following catagories:
- Couples going for consanguineous marriage
- If either/both have family history of a serious
genetic condition
- If they are ‘carriers’ of the same
faulty gene
- If they have exposure to some chemical or other
environmental agent
- Any abnormalities in the chromosomes
What tests are done in Premarital
Screening
Pre marital screening varies from one region to another
depending on the prevalence of the diseases in that
region. We offer Pre marital screening at three levels:
1. Basic package includes:
- Complete blood count (CBC)
- Blood group (ABO & Rh typing)
- Abnormal Haemoglobin studies (Hb Variants)
- G6PD- quantitative
- Sexually transmitted diseases,
a. HIV ½ antibody screening (3rd Genration)
b. Hepatitis BsAg screening
c. Hepatitis C Total Antibodies to Hep C Virus
d.
VDRL (Syphilis) (RPR)
e. Gonorrhea (Neisseria Gonorrhea) detection by
PCR
f.
Chlamydia Trachomatis (IgG and IgA)
2. Advanced Package includes:
- Basic Package
- Male infertility test (CBC, FBS, PPBS, BUN, Urine
rt, Semen rt, FSH, LH, Prolactin, Testosterone,
ASAB, Chlamydia IgG/IgA)
- Female Infertility test (CBC, FBS, PPBS, BUN,
Urine rt, Blood group, FSH, LH, Prolactin, TSH,
ASAB, Chlamydia IgG/IgA)
3. Advanced Genetic Package Includes:
- Basic Package
- Male infertility test (CBC, FBS, PPBS, BUN, Urine
rt, Semen rt, FSH, LH, Prolactin, Testosterone,
ASAB, Chlamydia IgG/IgA)
- Female Infertility test (CBC, FBS, PPBS, BUN,
Urine rt, Blood group, FSH, LH, Prolactin, TSH,
ASAB, Chlamydia IgG/IgA)
- Karyotyping
Counselling for the advanecd
level of premarital screening should be done by genetic
counsellor
Genetic counseling is or should be a part of premarital
screening. Genetic Counsellor can help to decide the
type of test the couple should consider. A details
of the family history, medical records and conditions
of family members from both the sides need to be provided
to the counsellors to have a proper advice from him.
If the couple are informed of the possibility that
they are at an increased risk of having a genetically
abnormal child, they can choose to plan conceptions
according to medical advice and can make use of the
genetic counselling services available, such as:
- Couples may decide not to get married
- If couples decide to get married, they may not
wish to have children
- If couples wish to have children, they must do
the Pre natal Screening of the fetus at an early
stage of pregnancy
- Couples must understand the option of termination
of the pregnancy
- Couples must understand the social, economic
perspectives of having children with genetic disorders.
1. Basic package:
The routine tests are done under this package to
check the health status of an individual. Any abnormality
will direct the couple for further analysis to an
advanced level. These are the regular biochemical
tests routinely done by the laboratories.
- Complete blood count (CBC)
- Blood group (ABO & Rh typing)
- Abnormal Haemoglobin studies (Hb Variants)
- G6PD- quantitative
- HIV ½ antibody screening (3rd Genration)
- Hepatitis BsAg screening
- Hepatitis C Total Antibodies to Hep C Virus
- VDRL (Syphilis) (RPR)
- Gonorrhea (Neisseria Gonorrhea) detection by
PCR
- Chlamydia Trachomatis (IgG and IgA)
2. Advanced package:
This includes the basic package with the addition
of infertility testing for both male and female. It
is always important to know the about the fertility
status of the couple as most of the time, specially
in the South East Asia, women are condemned for not
having children after years of marriage. Though its
interesting to know in many cases, the male infertility
was the reason behind this.
Although many people still think of fertility as
a "woman's problem," up to half of all cases
of infertility involve problems with the man. In fact,
about 20% to 30% of the time, a man's low fertility
is the main obstacle to conception.
So it's crucial that men get tested for fertility
as well as women. Yes, it can be embarrassing, but
discovering male fertility problems early can mean
earlier treatment and a successful pregnancy. Male
infertility testing can also spare women unnecessary
discomfort and expense.
A semen analysis is the most common testing procedure
for determining if there is a male infertility factor.
Sperm is collected into a specimen jar and presented
to a lab technician who examines the sperm under a
microscope to evaluate the count, shape, appearance,
and mobility.
When assessing sperm count, the technician will be
checking to see whether the sperm concentration is
above or below 20 million sperm cells per milliliter
of ejaculation fluid.
If the sperm count is low, your fertility specialist
will probably test the blood testosterone, FSH, LH
and prolactin levels.
A urinalysis may be used to look for white blood
cells which may indicate an infection. The urinalysis
will also determine if there is sperm in the urine,
which would suggest that there is a problem with ejaculation
known as retrograde ejaculation.
Infertility is the inability to get pregnant after
a year of unprotected intercourse. About 10% of couples
in the United States are affected by infertility.
Both men and women can be infertile. According to
the American Society for Reproductive Medicine, 1/3
of the time the diagnosis is due to female infertility,
1/3 of the time it is linked to male infertility and
the remaining 1/3 is due to a combination of factors
from both partners. For approximately 20% of couples
the cause can not be determined.
The tests performed by the specialists involves measuring
the level of the hormones, like, follicle stimulating
hormone (FSH) and luteinizing hormone (LH) to establish
a baseline. This is performed on the third day of
cycle. Other hormones and routine analyses are also
done to complement the diagnosis.
3. Advanced genetic package:
This is the most comprehensive package which includes
basic tests, fetility tests and adds karyotyping as
to analyze the chromosomes of both of them. For advanced
screening, blood karyotyping is suggested by the counsellor
to the couples who do not have any particular genetic
conditions. When the couples show the correct number
of chromosomes, there is less likely that they have
any genetic abnormalities in their chromosomes.
Blood Karyotyping is a test to examine chromosomes
in a sample of cells, which can help identify genetic
problems as the cause of a disorder or disease. This
test can:
• Count the number of chromosomes
• Look for structural changes in chromosomes
The sample is placed into a special dish and allowed
to grow in the laboratory. Cells are later taken from
the growing sample and stained. The laboratory specialist
uses a microscope to examine the size, shape, and
number of chromosomes in the cell sample. The stained
sample is photographed to provide a karyotype, which
shows the arrangement of the chromosomes.
Certain abnormalities can be identified through the
number or arrangement of the chromosomes. Chromosomes
contain thousands of genes that are stored in DNA,
the basic genetic material.
Normal Results
• Females: 44 autosomes and 2 sex chromosomes
(XX), denoted 46, XX
• Males: 44 autosomes and 2 sex chromosomes
(XY), denoted 46, XY
Other Tests to be considered
Couples might also consider taking specific Molecular
Cytogenetic or DNA tests if he/she has family history
of any of the following conditions. Carrier or mutation
analysis will help them to diagnose the status of
the couple.
List of DNA Tests:
• Achondroplasia
• Albinism-OCA
1 Tyrosinase gene sequencing/ Albinism-OCA 2 gene-Common
deletion
• Alkaptonuria-linkage
studies/ Prenatal Diagnosis-linkage
• Alpha 1 Anti
Typsin (Z, S & M Mutation)
• Alpha thalassemia-deletions
• Aneuploidy
screening (21, 18, 13, X, Y, chm)
• Angelman
Syndrome (methylation test)
• Apert Syndrome
• Apo E Genotyping
• Ataxia Telangiectasia-carrier
screening by linkage
• Ataxia Telangiectasia-PND
by linkage
• Canavan
Disease- Asparto asylase (ASPA) gene sequencing
• Charcot
Marie Tooth disease 1/ HNPP (Del/Dupl. PMP gene)
• CMV-Cytomegalovirus-PCR
• Congenital
Adrenal Hyperplasia-Common deletion
• Congenital
Adrenal Hyperplasia- 5 mutations
• Congenital
Adrenal Hyperplasia-deletions by dosage test
• Congenital
Adrenal Hyperplasia-Prenatal diagnosis-linkage
• Congenital
Adrenal Hyperplasia-Cyp 21 gene sequencing
• Craniosynostosis
( non specific) C749-FGFR 3
• Crigler
Najjar Syn.- UGT1A1 gene sequencing
• Cruozon
disease: FGFR 2 mutation (Ser 354 Cys)
• Cystic
Fibrosis- Diagnosis (Delta 508 mutation)
• Cystic
Fibrosis- 254 Mutations + Poly T
• Cystic
Megalencephaly- MLC1 gene sequencing
• Cystic
Megalencephaly- Prenatal Diagnosis CVS
• Deafness
Connexin 26 gene-sequencing
• DMD
deletion testing - 18 exons
• DMD
79 exons- deletion/duplication test
• DMD-Dosage
studies in females
• DMD
- Prenatal diagnosis + maternal cell contamination
• Dystonia
(DYT 1 gene- common deletion)
• Ectodermal
dysplasia X- linked –PND by linkage +MCC
• Ectodermal
dysplasia X- linked, gene sequencing
• Epidermolysis
bullosa dystrophia (PND- by linkage)
• Factor
V Leiden
• Familial
hypercholesterolemia (linkage, Prenatal)
• FGFR
3 gene sequencing (Ach, Hypochond, Thanatophoric dw)
• Folate
Polymorphism 3' 5 MTHFR ( 677C>T, 1298 A>C)
• Fragile
X Screen- PCR based
• Fragile
XA- methylation test
• Friedreich
Ataxia
• G-6-PD
one mutation
• Galatosemia
gene sequencing (GALT)
• Gaucher's
disease (4 common mutations)
• Gilbert's
disease (UGT1A1 Promoter polymorphism)
• Glycogen
storage 1a gene sequencing
• Hallorverden-Spantz
disease (PND by linkage)
• Hypochondroplasia
(Sequencing)
• Hemochromatosis
(2 mutations in HFE gene)
• Hemophilia
A/B, Carrier test
• Hemophilia
A/B, (Prenatal diagnosis)
• Herpes
Virus infection (PCR)
• Hunter
Syndrome - deletions
• Huntington
disease
• Hypochondroplasia-common
mutation C1620A in FGFR3
• Jak
2 mutation
• Krabbes
disease- common deletion
• Leb
Hered Optic Atrophy- 3 mutations
• Lowe
Syndrome - linkage studies/ family
• Lowe
Syndrome - Prenatal diagnosis-linkage
• Maternal
Cell Contamination
• Marfan
Syndrome-linkage studies
• Marfan
Syndrome - Prenatal diagnosis-linkage studies/ family
• MCAD
mutation (Medium chain acyl-coA dehyd)
• McArdle
disease (R49 X mutation, Sequencing)
• Merosin
deficiency-linkage/ PND
• Metaphyseal
Dysplasia-COL 10A gene sequencing
• Mitochondrial/
LEIGHS or NARP-3 mutations
• Mitochondrial
1/ MELAS + MERRF-5 mutations
• Mitochondrial
package (110, 111)
• Mitochondrial
genome- deletion/duplication
• Mytotonic
dystrophy- type 1-19q 13.3
• Mytotonic
dystrophy- type 2- 3q 21
• NCL
-infantile (2 mutation)
• NCL
-infantile (2 mutation)
• NCL
–Juvenile (Batten Dis) deletion
• Neuroblastomatosis
(linkage, PND)
• Parkinson
disease (Gly 19 ser mutation, by sequencing)
• Parvo
virus-PCR
• Pelizaeus
Merzbacher deletion/duplication
• Polycystic
Kidney dis (Aut. Rec. ARPKD) PND by linkage
• Porphyria-
Acute intermittent Common Mutation
• Porphyria-
Sequencing of Porphobilinogen gene
• Prader
Willi Syndrome-methylation test
• Prothrombin
gene polymorphism (G20210A)
• Restrictive
Dermopathy (Specific mutation by sequencing)
• Retinoblastoma-
deletion/duplication
• Retinoblastoma
(Prenatal diagnosis by linkage)
• Retinoblastoma
gene sequencing
• Rett
Syndrome MECP2 deletion/ duplication
• Rett
Syndrome MECP2 -Sequencing
• Rh
typing - (Rh+ or Rh-)
• Rh
typing on fetal DNA in maternal blood
• Rubella
(PCR)
• Russel
Silver Syndrome (UP Disomy)
• Spinal
Muscular atrophy, diagnosis
• Spinal
Muscular atrophy-PND
• SMA
Carrier Screening for deletion
• Spinal
Muscular atrophy- SMN 1 gene sequencing
• Spino-
Cerebellar ataxia -One type
• Spino-
Cerebellar ataxia -Two type
• Spino-
Cerebellar ataxia -package (1,2,3,6,7,8,12, 17 DRPLA)
• Spinal
bulbar muscular atrophy (SBMA) CAG repeats
• Spondyloepiphyseal
dysplasia X-linked gene sequencing
• Sry+Amxy
gene study (Y chromosome)
• Subtelomeic
deletions & duplications
• Thalassemia-beta
(Confirmation of known mutation)
• Thalassemia-beta
mutation study ( 5 common mutation)
• Thalassemia-beta
globin gene sequencing
• Thalassemia-Prenatal
diagnosis
• Thalassemia-Prenatal
diagnosis-Repeat at GRH
• Thanotrophic
dwarfism (common mutation)
• Thanotrophic
dwarfism sequencing
• Thrombophilia
Profile- 3 genes- MTHFR, Factor v Leiden,Prothrombin
• Toxoplasmosis
(PCR)
• Waardenburg
Syndrome Pax 3 gene sequencing
• Waardenburg
Shah syn- EDN3 gene-3 80A>G
• Wilson
linkage presymptomatic
• Wilson
diseases-PND by linkage
• Wilson
diseases-ATP7B gene sequencing
• UGT1A1
* 28 Genotyping
• X-linked
ichthyosis (Deletion in STS gene)
• XMN
Polymorphism Gr gene (thalassemia child)
• Y-Chromosome
deletions (10)
Courtesy: http://www.ameinfo.com/163283.html
http://jama.ama-assn.org/cgi/content/abstract/258/13/1757
Please visit the websites for further information
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