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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



  • 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)

Normal appearing female 46 xx

Normal Appearing Female46,XX

Normal male 46 xy

Normal Male 46,XY

Cell division reproduction


Cell division

All 46 chromosomes copy themselves

Both new cells have the same set of 46 chromosomes


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



  • 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

Trisomy 18 edwards syndrome

Trisomy 18 - Edwards Syndrome

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 syndrome

Turner Syndrome

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

Recessive inheritance

Recessive Inheritance

Autosomal recessive conditions

Autosomal Recessive Conditions

  • Cystic Fibrosis

  • Xeroderma Pigmentosa

  • Tay-Sachs

  • Sickle Cell Anemia



  • Eyes, hair and skin

  • Lack of pigment

  • 25% risk to children of carriers

Dominant inheritance

Dominant Inheritance

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 inheritance

X-Linked Inheritance

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

Pedigree fundamentals

Pedigree Fundamentals

Autosomal recessive it can be hidden and reappear

Autosomal Recessive(it can be hidden and reappear)

What inheritance pattern

What inheritance pattern?

Autosomal dominant

Autosomal Dominant

What inheritance pattern1

What inheritance pattern?

X linked dominant if father carries every girl has it

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

What inheritance pattern2

What inheritance pattern?

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)

Any ideas on this one

Any ideas on this one?

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


    • (test mother’s blood)

  • Amniocentesis

  • CVS

  • Nuchal Fold-

    • sonogram measures amount of fluid in fetus’ dorsal neck

Maternal serum screen

Maternal Serum Screen

Neural tube defects

Neural Tube Defects

Diagnostic testing

CVS – Chorionic Villi Sampling


Diagnostic Testing

Case 1

Case 1

  • Mother is 28 years old

  • Maternal Serum Screen indicates 1/30 for Down Syndrome



  • Thalidomide

  • Medications for maternal illness

Osteogenesis imperfecta

Osteogenesis Imperfecta

Marfan syndrome

Marfan Syndrome

Ehlers danlos syndrome

Ehlers-Danlos Syndrome



Prader willi syndrome

Prader-Willi Syndrome

Treacher collins syndrome

Treacher Collins Syndrome

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

  • The American Board of Genetic Counseling (ABGC)

  • Canadian Association of Genetic Counsellors

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

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