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Genetic Counseling. Ashley Carlson 1 st Year Genetic Counseling Sarah Lawrence College Bronxville, NY. What is a Genetic Counselor?. A health professional with experience in medical genetics and counseling. Provides information and support to families who:

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Genetic counseling

Genetic Counseling

Ashley Carlson

1st Year Genetic Counseling

Sarah Lawrence College Bronxville, NY


What is a genetic counselor
What is a Genetic Counselor?

  • A health professional with experience in medical genetics and counseling.

  • Provides information and support to families who:

    • have members with genetic disorders or birth defects

    • may be at risk for genetic disorders or birth defects

  • Practices non-directive counseling


How can i become a genetic counselor
How Can I Become a Genetic Counselor?

  • Obtain a specialized graduate degree in Genetic Counseling

  • Most enter the field from a variety of disciplines including biology, genetics, nursing, psychology, public health and social work. (NSGC 1983)

  • Having experience in counseling is very important


How did i become a gc
How Did I Become a GC?

  • High school – Took Chemistry, Biology I and II, and Physical Science

  • Undergrad – Biology, Genetics, Developmental Bio, Chemistry, Statistics, Evolutionary Bio, Genetic Technology, etc.

  • Experience in a counseling-based agency – Worked in a Battered Women’s Shelter

  • Volunteered for two prenatal Genetic Counselors in Wilmington, NC for one year


What made me decide to become a genetic counselor
What Made Me Decide to Become a Genetic Counselor?

  • Senior Exit Project

    • The idea came from my brother

  • Interviewed two genetic counselors

  • Personal History

    • Arnold-Chiari

      Malformation I


Chromosomes
Chromosomes

  • They are the packages that contain our genetic material – our genes

  • All of our cells have 46 chromosomes

  • Half (23) are inherited from each parent

  • Chromosomes exist in pairs (23 pairs)




Cell division reproduction

Mitosis

Cell division

All 46 chromosomes copy themselves

Both new cells have the same set of 46 chromosomes

Meiosis

How egg and sperm are formed

One cell with 46 chromosomes divides twice resulting in 4 cells that each have only 23 chromosomes

Cell Division/Reproduction


Nondisjunction
Nondisjunction

  • Failure of paired chromosomes to separate during meiosis in Anaphase I

  • Leads to egg or sperm with extra or missing chromosomes

  • When abnormal egg/sperm is used for fertilization, the result is an aneuploid embryo


Down syndrome
Down syndrome

  • Most common live born chromosome disorder

  • Extra 21 chromosome

  • Prevalence: 1:800 births

    • 350,000 people in USA

  • Mental retardation

    • Characteristic facial features

    • Heart defects

    • Vision/hearing problems

    • Increased risk of Leukemia and Alzheimer's



Edwards syndrome
Edwards Syndrome

  • 1:8000 live births

  • Mental deficiency

  • Small jaw

  • Short sternum

  • Heart defects

  • Malformed ears

  • Rocker-bottom feet

  • Characteristic clenched fist

  • 90% die before 1 yr



Turner syndrome1
Turner Syndrome

  • 1:8000 live births

  • Webbed neck

  • Puffiness of hands and feet

  • No sexual maturation

  • Broad chest and widely spaced nipples

  • Learning difficulties


What are genes
What Are Genes?

  • Genes are the units of heredity we receive from our parents

  • They are packaged at specific locations (loci) on our chromosomes

  • Like chromosomes, they occur in pairs, one from each parent

  • They are sequences of DNA


Reasons for genetic disease
Reasons for Genetic Disease

  • A change in a gene from its natural state

  • Changes can be inherited or acquired

  • Genes themselves do not cause disease

  • Mutation = gene malfunction = malformed or absent gene product = disease

  • “She has the breast cancer gene…” means she has a mutated version of that gene

  • ALL of us have some version of the Breast Cancer Gene or BRCA



Autosomal recessive conditions
Autosomal Recessive Conditions

  • Cystic Fibrosis

  • Xeroderma Pigmentosa

  • Tay-Sachs

  • Sickle Cell Anemia


Albinism
Albinism

  • Eyes, hair and skin

  • Lack of pigment

  • 25% risk to children of carriers



Autosomal dominant conditions
Autosomal Dominant Conditions

  • Achondroplasia – dwarfism

  • Familial Breast Cancer – BRCA1 and 2

  • Huntington Disease


Crouzon s syndrome
Crouzon’s Syndrome

  • Premature fusion of the skull bones

  • Wide, shallow eyes

  • Hearing loss



X linked traits
X-Linked Traits

  • Color blindness

  • Hemophilia

  • Fragile X

  • x-linked dominant: “Incontinentia pigmenti” -various severity from skin abnormality to CNS problems


Fragile x syndrome
Fragile X Syndrome

  • Most common cause of inherited mental impairment

  • Caused by expanding area of DNA on chromosome X (CGG Repeat)

  • Prevalence:

    • 1 in 4000 males

    • 1 in 6000 females

    • All races and ethnic groups


What happens during a genetic counseling session
What Happens During a Genetic Counseling Session?

  • Family history is taken

  • Discuss medical/genetic problems in general

  • Provide risk assessment

  • Discuss testing options, in terms of risks, benefits and limitations

  • Consent patient for testing


Pedigree construction
Pedigree Construction

  • Geneticists’ fundamental tool

  • Allows for easy construction of a multi-generational family history

  • Simple method for detailed documentation of inheritance of a particular trait in a family

  • Can often assess the inheritance of a trait based on pattern of affected individuals



Autosomal recessive it can be hidden and reappear
Autosomal Recessive(it can be hidden and reappear)





X linked dominant if father carries every girl has it
X-Linked Dominant(if father carries, every girl has it)



Y linked all sons of affected fathers are affected ex tdf testes determining factor
Y-linked(all sons of affected fathers are affected, ex; TDF-testes determining factor)



Mitochondrial inheritance all children get mitochondria of mother
Mitochondrial Inheritance(all children get mitochondria of mother)


Prenatal genetics
Prenatal Genetics

  • Women who are at increased risk to have a child with a genetic disorder/ birth defect

    • Advanced maternal age

    • Family history of medical problem/genetic disease

    • Exposure to drugs, alcohol, medication

    • Prenatal sonogram abnormalities


Maternal age effect
Maternal Age Effect

  • As the age of the mother increases, there is an increased risk for a chromosome abnormality in their child.


Different prenatal testing
Different Prenatal Testing

  • MSAFP

    • (test mother’s blood)

  • Amniocentesis

  • CVS

  • Nuchal Fold-

    • sonogram measures amount of fluid in fetus’ dorsal neck




Diagnostic testing

CVS – Chorionic Villi Sampling

Amniocentesis

Diagnostic Testing


Case 1
Case 1

  • Mother is 28 years old

  • Maternal Serum Screen indicates 1/30 for Down Syndrome


Teratogens
Teratogens

  • Thalidomide

  • Medications for maternal illness








Case 2 huntington disease
Case 2: Huntington Disease

  • Woman is 31 years old

  • Has a sister and father with HD

  • Wants to be pregnant without knowing her HD status

  • Goes through 2 rounds of Preimplantation Genetic Diagnosis (PGD)  unsuccessful

  • At 34 she becomes pregnant naturally


Case 3 cancer genetics
Case 3: Cancer Genetics

  • Breast cancer in a family with Ashkenazi Jewish heritage

  • Unaffected father worried about two daughters: 28 and 23 yrs


Information websites
Information Websites

  • National Society for Genetic Counselors

    http://www.nsgc.org

  • The American Board of Genetic Counseling (ABGC)

    http://www.abgc.net

  • Canadian Association of Genetic Counsellors

    http://www.cagc-accg.ca


Caroline lieber director of the joan h marks graduate program in human genetics

For more information contact:

Caroline LieberDirector of The Joan H. Marks Graduate Program in Human Genetics

Sarah Lawrence College

1 Mead Way

Bronxville, NY 10708

Tel: 914.395.2371

http://www.slc.edu/grad_humangenetics.php


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