By Dr. Salah Jadallah

Genetic Counselling

What Is Genetic Counseling?

Genetic counseling is the process of: evaluating family history and medical

records ordering genetic tests evaluating the results of this

investigation helping parents understand and reach

decisions about what to do next

الور مهمة ااالستشارة ثيةتساعد النها الزواج في قبل

الوراثية االمراض كشفتبقى   التي واالمراض

اخر الى جيل من منتقلة

Genetic Counseling strong communicative and

supportive element

الزواج قبل ما فحوصات إجراءوالفحص الحمل أثناء والفحص

واالستشارة للمواليد المبكرالوسائل أفضل من تعد الوراثية

األمراض انتشار من للحدعالجها يمكن ال التي الوراثية

نهائي بشكل

Genetic counselor Genetic counselors can help identify

and interpret the risks of an inherited disorder, explain inheritance patterns, suggest testing, and lay out possible scenarios.

He refers you to a doctor or a laboratory for the actual tests.

The best time to seek genetic counseling is before becoming pregnant, when a counselor can help assess your risk factors. But even after you become pregnant, a meeting with a genetic counselor can still be helpful.

للبحث الوراثية االستشارة من الهدفومحاولة المرضي العائلة تاريخ فيوراثية امراض هناك كان اذا معرفة

بسبب االجنة وفيات حاالت وجود مثل   متكررة اجهاض حاالت او خلقية عيوباالعاقات بعض لديهن مواليد وجود او

او البصر او السمع في الخلل او. العلمي التحصيل في تأخر او النطق

( اإلخوة األولى الدرجة من اإلخوة ) أقارب األولى الدرجة من أقارب) واألبناء ، واآلباء ، (واألخوات واألبناء ، واآلباء ، واألخوات

( ، عمة ، عم الثانية الدرجة من ، ) أقارب عمة ، عم الثانية الدرجة من أقارب) أخت بنت ، شقيق ابن ، (جد أخت بنت ، شقيق ابن ، جد

) العم ) ابناء الثالثة الدرجة من (أقارب العم ) ابناء الثالثة الدرجة من أقارب

إلجراء المرشحين المرضى هم منوراثية؟ استشارة

وراثي لمرض عائلية أو شخصية .قصة خلقي تشوه صبغي اضطراب تورث التي السرطانية األمراض أكثر أو للحمل اسقاطين قصة متوفى مولود والدة من أكثر بعمر الحامل التي 35المرأة أو سنة

العمر هذا بعد بالحمل ترغب صبغية أو وراثية مشكلة ترجح دموية .تحاليل معين عرقي ارتباط لها الوراثية األمراض بعض... ( الخ خال أو عموم أبناء القرابة ذوي األزواج

Why Genetic Counselling is Recommended Counselling is recommend for

any of the following reasons:1- A couple plans to start a family

and one of them or a close relative has an inherited illness.

2- A parent already has one child with a severe birth defect.

Not all children who have birth defects have genetic problems.

Sometimes, birth defects are caused by exposure to a toxin (poison), infection, or physical trauma before birth. Often, the cause of a birth defect isn't known.

Even if a child does have a genetic problem, there's always a chance that it wasn't inherited and that it happened because of some spontaneous error in the child's cells, not the parents' cells.

3- A woman has had two or more miscarriages. Severe chromosome problems in the fetus can sometimes lead to a spontaneous miscarriage.Several miscarriages may point to a genetic problem.

4- A woman has delivered a stillborn child with physical signs of a genetic illness.Many serious genetic illnesses cause specific physical abnormalities that give an affected child a very distinctive appearance.

5- The pregnant woman is over age 34. Chances of having a child with a chromosomal problem (such as trisomy) increase when a pregnant woman is older. Older fathers are at risk to have children with new dominant genetic mutations (those caused by a single genetic defect that hasn't run in the family before).

6- A standard prenatal screening test had an abnormal result.If a screening test indicates a possible genetic problem, genetic testing may be recommended

7- A child has medical problems that might be genetic. When a child has medical problems involving more than one body system, genetic testing may be recommended to identify the cause and make a diagnosis.

8- A child has medical problems that are recognized as a specific genetic syndrome. Genetic testing is performed to confirm the diagnosis. In some cases, it also might aid in identifying the specific type or severity of a genetic illness, which can help identify the most appropriate treatment.

Steps in Genetic Counseling

Genetic counseling generally involves six steps:

Family and medical history assessment.

Analysis of genetic information (e.g., family history, genetic test results).

Communication of genetic risk information.

Education about inheritance, genetic testing, management, risk reduction, resources and research opportunities.

Supportive counseling to facilitate informed choices and adaptation to the risk or condition.

Follow up.  This may include a written summary, provision of referrals, and/or subsequent genetic counseling session(s). 

Factors increasing Risk

Maternal Age Paternal Age Ethnicity Family history

considerations

Maternal Age

Women over the age of 35 Slightly increased risk for

chromosome condition Down syndrome- extra #21 Trisomy 13 and 18- extra 13 & 18

severe Sex chromosome conditions

Paternal Age increased risk for: achondroplasia Marfan Noonan

وتيرة زيادة إلى تشير وتيرة الدراسات زيادة إلى تشير في في الدراساتaneuploidyaneuploidy العقود في المنوية العقود الحيوانات في المنوية الحيوانات

والسابع والسابع السادس السادس

Genetic Disorder Chromosomal disorder Single-gene disorder Mitochondrial genetic

disorder Multifactorial disorder Somatic cell genetic

disorder

Single-gene disorder Autosomal dominant: Achondroplasia; Marfan

syndrome Autosomal recessive: Albinism; Cystic fibrosis;

PKU X-linked dominant: Hypophosphatemic X-linked recessive: DMD; Hemophilia; G6PD

deficiency Y-linked: Haired ears Triplet repeats: Fragile X syndrome; Myotonic

dystrophy Mitochondrial: Leber’s hereditary optic

neuropathy (LHON), MERRF syndrome  (Myoclonic Epilepsy with Ragged Red Fibers). MELAS “Mitochondrial encephalomyopathy, lactic acidosis”

AR

AD

XR

XD

Y- Linked

Mitochondrial inheritance

األسباب المتعددة األمراض , الدم ضغط وارتفاع السكر , مرض

) والربو, الصلب المشقوق الظهر واألرنبية(, الشفة و المشقوق

Genetic Testing During Pregnancy

Amniocentesis: - test usually performed between weeks 15

and 20 of a woman's pregnancy. - a small amount of amniotic fluid from around

the developing fetus is taken. - This fluid can be tested to check for genetic

problems and to determine the sex of the child, Chromosomes, Enzymes, AFP- protein

Chorionic villus sampling (CVS): performed between the 10th and

12th weeks of pregnancy. The doctor removes a small piece

of the placenta to check for genetic problems in the fetus.

This can be tested to check Chromosomes, Enzymes, DNA

Ultrasound

This can be tested to check Fetal Anatomy

PCR

FISH technique Fluorescence in situ hybridization (FISH)

is used to visualize and map the genetic material in an individual's cells, including specifc genes or portions of genes.

This is important for understanding a variety of chromosomal abnormalities and other genetic mutations.

FISH technique

 chromosomal t (9;22)

PGD “Preimplantation genetic diagnosis”

Gene therapy Gene therapy carries the promise of

cures for many diseases and for types of medical treatment that didn't seem possible until recently. With its potential to eliminate and prevent hereditary diseases such as cystic fibrosis and hemophilia and its use as a possible cure for heart disease, AIDS, and cancer

gene therapy is a potential medical miracle-worker.

But what about gene therapy for children? There's a fair amount of risk involved, so thus far only seriously ill kids or those with illnesses that can't be cured by standard medical treatments have been involved in clinical trials using gene therapy.

As those studies continue, gene therapy may soon offer hope for children with serious illnesses that don't respond to conventional therapies.

About Newborn Screening Testing every newborn for certain harmful

disorders at birth. Many of these are metabolic

disorders "inborn errors of metabolism") that interfere with the body's use of nutrients to maintain healthy tissues and produce energy.

Other disorders that screening can detect include problems with hormones or the blood.

What are common genetic disorders? Cystic fibrosis – Cystic fibrosis is

tested by examining 32 different mutations in a particular gene. The disorder affects the normal movement of salt in and out of cells that line the lungs and pancreas. This produces a thick, sticky mucus which leads to frequent lung infections.

Down syndrome – Down syndrome is the most common genetic birth defect, often resulting in multiple abnormalities. It is caused by an extra chromosome and results in some degree of mental retardation, heart defects and problems with vision and hearing. Down syndrome is tested for by taking a blood sample and performing a chromosome analysis.

Neurofibromatosis I – Neurofibromatosis I is caused by mutations in the NF1 gene. This gene makes a protein called neurofibromin, which is responsible for keeping cells from growing and dividing rapidly. Mutations in the NF1 gene cause tumors to form on nerves throughout the body.

Sickle cell disease – Sickle cell disease is caused by a red blood cell disorder.

Hemoglobin electrophoresis, a test that measures the different types of hemoglobin in the blood, is used to diagnose the disease.

Tay-Sachs disease – Tay-Sachs disease is caused by the absence of a vital enzyme called hexosaminidase-A (Hex-A). Without Hex-A, a fatty substance builds up in cells, especially in the brain’s nerve cells. This ongoing buildup causes progressive cell damage. Tests for the disease measure the amount of Hex-A in the blood or in white blood cells.