| what is karyotyping (chromosomal study) ? |
| how is karyotype done? |
| when we consider doing chromosomal study? |
| Down’s syndrome: |
| what is down’s syndrome ? |
| are there “degrees” or “levels” of down’s syndrome ? |
| how to prevent down’s syndrome ? |
| is there any treatment for down’s syndrome? |
| neonatal screening: |
| which disorders can be detected ? |
| is these a cure for such disease ? |
| are there other identifiable disorders after delivery ? |
| how is the test done? |
| triple test (prenatal screening): |
| who should consider having the triple blood test ? |
| when the test is done ? |
| what does a “screen negative” result mean ? |
| what does a “screen positive” result mean ? |
| what to do if the test is “screen positive” ? |
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Chromosomes: |
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| 1 |
what is karyotyping (chromosomal study) ? |
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it is the study of the human chromosomes to detect any abnormality in the number (normally it is 46) or the shape of chromosomes |
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how is karyotype done? |
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Chromosomal study can be done from any cell in the body , the easiest is the white blood obtained by a simple blood sample . it can also be done from bone marrow cells in cases of some tumours e.g leukaemia or from amniotic cells to diagnose abnormalities of the fetus during pregnancy or from products of conception to role out the cause of repeated miscarriages or abortions.
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when we consider doing chromosomal study? |
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It should be considered in the following cases:-
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congenital malformations |
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mental retardation |
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down’s syndrome |
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cancer |
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repeated abortions |
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intersex |
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infertility |
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delayed puberty
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failure in schools achievement |
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hyper active child
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premarital testing (some cases only) |
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family history of any of the above
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Down’s syndrome: |
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| 1 |
what is down’s syndrome ? |
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it is a congenital disease due to abnormal no. of chromosomes (47 instead of 46 an extra copy of chromosomes no. 21) this leads to mental retardation and delayed development of physical mile stones |
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are there “degrees” or “levels” of down’s syndrome ? |
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NO, but there are “types” which are:
1-the classic type 95%
2-the mosaic type 2%
3-the heridetravy type 3%
all types are alike and the prognosis depends upon the medical treatment care of the family and the early intervension programme
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how to prevent down’s syndrome ? |
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by doing screening test during pregnancy regardless of the age of the mother , it is done either from 9-13 weeks or from 15-22 weeks of pregnancy . |
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is there any treatment for down’s syndrome? |
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Yes , these children are ‘slow learners’ so with good medical care and family support and early intervension programme we can reach very good results. |
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neonatal screening: |
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these are groups of tests done to every newborn to detect some serious genetically determined diseases , these diseases are not manifested immediately after labour |
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which disorders can be detected ? |
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mainly four diseases are detected :
congenital hypothyroidism , calactosemie, phenylketonurea (pku) and glucose and phosphate dehydrogenase deficiency (g6pd) |
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is these a cure for such disease ? |
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Yes , if diagnosed early before symptoms appear , BUT if the disease is manifested mental retardation is enivetable (except in cases of g6pd) |
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are there other identifiable disorders after delivery ? |
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Yes, around 30 other disorders are identifiable each according to the suspected disorder |
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how is the test done? |
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It is done on day 5-7 after birth preferably , we take four drops of the blood from the infants heel on a special filter paper. |
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triple test (prenatal screening): |
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it is well know that 2 – 5 % of all births suffer from mental retardation and congenital malformation , the majority of these babies may have :
downi syndrome , trisomy 18 , neural tube defects and abdominal wall defects . this test gives us the risk of occurrence of such diseases . |
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who should consider having the triple blood test ? |
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All pregnant women regardless of their age . if a women or her husband has a family history of inherited disease , she should discuss the test with the genetic counselor . |
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when the test is done ? |
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either from 9 – 13 weeks of pregnancy, in this case we read to do an ultrasound for the baby or later on between 15 – 22 weeks of pregnancy . |
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what does a “screen negative” result mean ? |
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it means that the risk for a specific birth defect is low and there is no need for further diagnostic tests . |
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what does a “screen positive” result mean ? |
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it means that the risk for specific birth defect is high and we have to do a diagnostic test . |
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what to do if the test is “screen positive” ? |
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you should discuss this result with your doctor or genetic counselor for the possible options which are : genetic counseling , ultrasound or amniocentesis . |
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