Genetic Illness Recognition Before Birth (Prenatal Diagnosis):
Prevention of genetic sick's in society is the safest way. With on time distinction before birth, we can prevent of the birth's babies with sex-linked, parental and genetics' sickness. Indeed, recognition before birth is using the different diagnosis for check the baby's condition on conception's circulation.
Genetics' illness, generally don't treat after birth many of illness and genetic syndrome's that have seen in embryo on the time of birthing, are will diagnosis them before birth, like as born syndrome, or after birth like as Talasemia and Hemophilia.
This ills result to babies death on first month after birth or may eith them for years it depend on to forces and kind's that. In the second situation result to very most costs for ill's family and society that's moreover the ill's torture on their duration's life. For example only on genetic illness, Hemophilia classic kind (A), that is due to defect in elation factor (FVIII) .
According to Iran Hemophilia society's reports, the cost of every Hemophilia illness with numeration of capitation of hygiene and freat ment's cost for every year for every one is 150 $, that is equal for 6500 person. With notice on, now, there are 5-6 thousand Hemophilia illness in country, this cost equal for capitation of hygiene and treatment's cost of half of countries' population. Nowadays, with these progress in molecular genetics' in potential, that's provide to diagnosis before birth for cell of genetics' illness that was recognition the illness gene's cause.
So, for control of spread the genetic illness in society, it needs to be prepared a obligatory proceedings for identification genetic illnesses transporters and diagnosis before birth. Diagnosis before birth gives the chance to parent to inform of embryos situation, and they have decision for conception continuation.
And they can collect the facilities for having a healthy child for partner's that they have pathogen gens transporter.
Check the Embryonic Sample Genetic:
The Embryonic sample that derivative of embryo before birth, have different genetics and biochemist test. The kind of test order on basis of first information as regards genetic illness or probable danger for one particular genetic illness. Diagnosis genetics test are two forms: cytogenetic (chromosomal Analyze) and molecular.
A) Cromozical Analyze:
Chromosomal analyz proposed on embryonic sample under this condition.
1- Mother's age doesn't above 35 years on time of conception in these cases; there is increase in chromosomal disorders. For example, in Down syndrome, the risk of embryo affection in conception's on 35 years or upper is very increase.
2- The existence of previous child with anyone syndrome's Trisomy (example down syndrome, Kline felter) or any other pathy (Turner syndrome). In these cases, through parents haven't any chromosomal pathy but in subsequent conceptions the risk of repetition of any chromosomal pathy is whereabouts 1%. That is four double of the society risk.
3- The existence of chromosomal pathy in every partner for instance aneuploidy (decrease or increase of chromosome), relocation, elimination or chromosome inversely with clinical worth. Some of chromosome inversical is natural, for example, pry centric chromosome 9.
4- The existence of high risks for the illness that it depends to sex that. There isn't destination before birth for that particular ill or in the cases that there is genetic destination before birth, but it doesn't need to destination embryo's sex before doing a test (example, muscular Ditrofy doshen or Hemophilia). In these cases, if the sex of embryo is girl, the next genetics test hasn't done on that.
5- In the cases that one partner has transporter chromosome X fragile (fragile X syndrome). In Many cases psychic mustiness, the major agent is fragile X chromosome in parent or the nearest illness family. In these cases, in most, mothers transport the fragile X chromosome that it is distinit with blood molecular environmental cheep easily. The distinction of emetic's pathy on embryo is possible by doing with using of pair nap sample or Amniotic cells in first three month of conception.
6- The existence of most risk for Down syndrome on basis of results of Alfa fetoprotein serum check (MSAFP) in alone or with serum free strioul (UE3) and pair gonadotropin hormone (HCG) in low conceptions (below 35 years old).
7- In unnatural sonography for instance anatomic pathies in embryo as amfalosel, or Hidrocephalus or another pathies that they can relate with chromosomal fault. Usually, the anatomic pathies can diagnosis in first three month. But, if they recognition in second or thirty three month, the chromosomal check can useful. In this case, the belly button line blood sample or pair naps can use for chromosomal analyzes.
B) Molecular Tests:
The using of molecular genetics in genetic illness check for diagnosis before birth is spread daily. This checking is inclusive that ills have recognition fault jen's ills agent. In another world, any genetic ill that diagnosis the agent gen on that we can diagnosis and cheek by molecular. The molecular cheek of genetic ills, usually doing on acid deoxyribonucleic molecule or DNA. In all of man's cells, genetic substance or gens (heredity substance) is gender of DNA. This substance in all body nucleate cells, for instance blood white cells are equal. So, the checking of all human genes structure with checking a derivation DNA from environmental blood cells is possible. In diagnosis before birth of genetic ills with recognition gens fault, it's a possible to checking on kind of embryo's tissue. The tissues that usually using for this result includes pair naps tissue, amniotic liquid cells, belly button tie blood, cells or embryo DNA in mother's blood.
We notice that, it's possible to diagnosis before birth in the cases that it was determined the gene's fault in parent that they are transporter. For example, for diagnosis before birth of genetic betatalasimi ill's --that is very spread in country, at first, two parts have to do the genetic test to determine the kind of the gene's spurt. This test it name is first station, need to do before conception. Because, in some cases, the gene's spurt may rare or it diagnosis need more time 2-3 month. In this case, if after conception, the test is done and embryo have heritage two parent gene's spurt (major), it may not to feticide because of legal limitation of 16 month conception. The second stages of test include checking the embryo's situation.
In this stage, the existence of parent spurts in embryo's sample (Amniotic cells or pair naps).
Diagnosis Methods Before Birth:
The diagnosis before birth method need to availability to embryo or embryonic sample that it does with different methods, instance invasive and Non-invasive.
A) Invasive Methods:
1- Amino synthesis
2- Chorionic villi sampling or (CVS)
3- Percutaneous umbilical blood sampling or (PUBS)
4- Biopsy from skin, bodies or embryo's muscular
5- Preimplantatior genetic diagnosis or (PGD) in conception eith IVF method.
B) Non- Invasive Methods:
1- Ultrasonegraphy (Three or four dimension)
2- Diagnosis on cells and embryonic DNA in mother blood.
3- Diagnosis on the mother serum. In blew, the sampling method from embryo and
their importance in diagnosis before birth is checking on clipping.
Chorionic Villi Sampling (CVS):
The more advantage in use of chorionic villi tissue is the early diagnosis on the embryo. That tissue gives by particular cutter under sonography as trance vajinal or from over the abdomen from pair (couple) on 10-12 weeks of conception. The amount of accuracy and assurance are rather equal on two method of sampling. The afore mentioned tissue moreover molecular tests, is using for chromosomal analyze, too. In comparison with amniosantez, moreover the possibility of faster to results, the most of cells are option for molecular analyze. But, the risk of feticide in CVS method is 0.5-1 amount, more than amniocentesis method. But it hasn't numerical mean.
The study's show that, the sampling on ninth week of conception is power attendant with body fault and face and body pothies. That it need to be notice in sampling time. The defects of chorionic villi sampling is the possibility of embryonic sample impurity with mother cells that is more the impurity with amino synthesis method. But, in molecular tests before diagnosis to illness gen, the amount of impurity of embryonic sample to mother cells is checking.
Amniotic Cells Sample (Amino Synthesis):
Amniocentesis in 14-16 week of conception as sampling from over abdomen is one of the usual invasive methods for embryonic cells and amniotic fluid. The amniotic cells moreover molecular tests, those are suitable for cytogenetic and cells tillage too. Moreover, amniotic fluid can use for biochemical checking for several factors for instance, Alpha-fetoprotein (AFAFP), enzymes, hormones. And another composition. The risk of feticide in this method is about 0.5. The most important point about chorionic villi sampling or amniocentesis is the risk of Rh sensitization that it take that mother's Rh- and embryo's Rh+. This problem can solve by using of amino globulin Rh coincide with sampling. With notice there isn't possible for do the amniocentesis before 14 weeks conception for the reason of few amount of amniotic fluid. And that isn't confirmed it's surfed. This method use for checking cytogenetic mostly.
In IVF conception, it's possible to check the embryo situation before implant. In this method, from embryo one or two doblastomer in eight cells blastosist stage. And then evaluate by genetic. Now, this method doing for determine of embryo's sex and a few genetics' illness.
Non-Invasive Method for Diagnosis Before Birth:
The CVS method and amniocentesis are in invasive methods group. Usually, doing these methods need to hospitalization and sampling have done by conversant women's expert. Moreover, this method may fetieide because of straight availability to embryo environment. We are checking some of this method in below.
Ultrasonography's method done as three or four dimension is the most common methods for diagnosis before non-invasive birth. In this method, there isn't any risk for mother or embryo. In this method, the best time for check the anatomic phathy in embryo is 15-20 week of conception. In this time, checking the Nuchal thickening in Down syndrome diagnosis is more important. And we can diagnosis fault in some of internal organs, neural tube defect, on embryo, too. If the result of sonography is unnatural, we need to proper consistency by using another method.
2. Diagnosis on Basis of Embryo's Dna in Mother Blood:
We can diagnosis the embryo's DNA in mother's blood after 8 week of conception. Although, the source of aforementioned DNA, isn't determined but the diagnosis before birth is prepared by this method.
It is doing the embryo's sex evaluation, Rh and some autosomi illness instance Econdroplazi on embryonic DNA in mother's blood in the many labratoraries rotten.
3. Cheek the Embryonic Cells in Mother's Blood:
Moreover embryonic DNA, we can recognition embryonic cells in mother's blood, too. Nowadays, wide-spread investigations about separating the afore mentioned cells are doing. The separating methods are based on special antigen's embryo on surface of cells.
4. Diagnosis Before Birth by Biochemical's Check in Mother's Serum:
Its usual to measurement some biochemical's factors in blood (serum) of conception's mother in the Non-invasive diagnosis methods before birth. With notice the importance of factors clinical aforementioned and the Non-invasive nature of their measurement, that's do for all mothers in many countries. In this relation, the below factors is very important in relation with embryo's situation.
* Alpha-fetoprotein, MSAFP
* Beta-human chorionic gonadotropin, b-HCG
* Unconjugated steriol, uE3
* A (Inhibin A)
* Pregnancy-associated plasma protein A, PAPP-A
Aforementioned factors as alone in some cases (MSDFP) or as coincide (Triple or quadruple) was measured. Between above factors, MSAFP has the most worth. In below, we check the AFP source and the it's diagnosis worth and another factors in diagnosis before birth of genetic ills.
Alpha-fetoprotein: In growth of embryo have two major blood proteins as albumin and alpha-fetoprotein (AFP). With notice that there is only albumin in adult's serum, sp, the Alpha-fetoprotein serum has a embryonic source. Coursly, a few amount of AFP come to amniotic fluid and pass from pair and come to mother blood. But, in infect cases in nervous tube example Enensefali (haven't closed the and of nervous tube cranial) and Spina bifida (don't close the and of nervous tube kadol) or Omphalocele and Gastroschisis in two case, there is in feet in wall of embryo's abdomen--most amount of AFP come in amniotic fluid and then com in to mother's blood.
With notice to increase the embryo's age and its size, the amount of AFP that free is increase, so when we measure the MSAFP we, have to determine the embryo's age.
The existence of conception's diabet affects to amount of AFP, too. MSAFP, usually report by multiples of the mean, MoM. The amount of mean in different populations determine with public bolstering in conception circulation. If MoM is high, the possibility of existence a fault in embryo is increase. The checking of MSAFP on 16-18 week of conception is more sensitive. Although in 15-22 distance, it has the high clinical worth, too. But, with notice that the amount of AFP is affected with different factors, it can changed, the increase. That can't sample of pathy in nervous tube 100%. With using MSAFP and ultrasonography coincide, approximately all instance of anencephaly and more of instance the spinabefida can diagnosis. It's possible to differential diagnosis's fault in nervous tube from other embryo's defect (example gastroshiz) with measuring the acetylcholi-nesterase amount in amniotic fluid.
The coincide increase of acetylcholine-esterase and MSAFP is the marker of defeet in nervous tube. If we can't determine amount of acetylcholine but MSAFP is high, it may the existence of defect in another's part. The checking of MSAFP is very important in diagnosis before birth of Down syndrome and other trisomies. The amount of MSAFP in conception with Down syndrome and another cromozomical pathies are decrease.
Human chorionic gonadotropin: (beta-HCG) the checking the amount of beta-HCG usually do as conception test.
In natural, with start the first week of conception and embryo's nesting in womb's wall, the amount of beta-HCG is increase enough, it can measure in serum. In the middle or end of second there month of conception, measuring the amount of beta-HCG coincide with MSAFP doing for cromozomical pathies about Down syndrome. The increase of beta --HCG and decrease of MSAFP can determine the existence of Down syndrome.
Un Conjugated Steriol Serum:
(uE3) The amount of steriol in mother's serum can relate with embryo's life, natural the well doing of pairs operation and good situation for mother. Steriol made from dehydroepiandrosterone that made by embryo's adrenal and source in metabolic pairs. Stariol passing from pair and come to mother's blood and void by kidneys or liver in bile. So the frequently measuring of steriol in third three month of conception is very useful for evaluate the embryo's situation. In the case of down syndrome and or Hypopelazi adrenal with enesefaly, decrease the amount of steriol.
Inhibin substance exudation from pair and corpus luteum. Afore mentioned substance can measure in mother's serum. The increase of inhibin-A co inside with increase in risk of trizomi 21.
The decrease in amount of PAPP-A serum in first three month of conception can marker of chromosomal palties for example 21, 18, 13 trisomies.
With notice that subject that change in all surface of afore mentioned factors can co inside with genetic pathies in embryo, the aforementioned factors usually evaluate in three tests. Co inside, including MSAFP, beta-HCG and uE3 that it doing with increase the inhibin- A and doing four to four.
DNA technology has led possible the diagnosis of many genetic diseases. It will play an increasing role in research and diagnosis of a growing number of inherited diseases, that will become amenable. The increase of knowledge and the technical development will be exploited and quickly transferred to the clinical laboratories. However, the widespread diffusion and the transferibility of these technologies will need to develop protocols and to take care of possible ethical problems
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Sharrif Moghaddasi M.
Islamic Azad University/Saveh Branch, Iran.
Sharrif Moghaddasi M., Islamic Azad University/Saveh Branch, Iran.
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|Title Annotation:||Original Article|
|Author:||Sharrif, Moghaddasi M.|
|Publication:||Advances in Environmental Biology|
|Date:||Apr 1, 2011|
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