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Genetic Counseling

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

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  1. Genetic Counseling Ashley Carlson 1st Year Genetic Counseling Sarah Lawrence College Bronxville, NY

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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)

  7. Normal Appearing Female46,XX

  8. Normal Male 46,XY

  9. 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

  10. 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

  11. 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

  12. Trisomy 18 - Edwards Syndrome

  13. 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

  14. Turner Syndrome

  15. Turner Syndrome • 1:8000 live births • Webbed neck • Puffiness of hands and feet • No sexual maturation • Broad chest and widely spaced nipples • Learning difficulties

  16. 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

  17. 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

  18. Recessive Inheritance

  19. Autosomal Recessive Conditions • Cystic Fibrosis • Xeroderma Pigmentosa • Tay-Sachs • Sickle Cell Anemia

  20. Albinism • Eyes, hair and skin • Lack of pigment • 25% risk to children of carriers

  21. Dominant Inheritance

  22. Autosomal Dominant Conditions • Achondroplasia – dwarfism • Familial Breast Cancer – BRCA1 and 2 • Huntington Disease

  23. Crouzon’s Syndrome • Premature fusion of the skull bones • Wide, shallow eyes • Hearing loss

  24. X-Linked Inheritance

  25. X-Linked Traits • Color blindness • Hemophilia • Fragile X • x-linked dominant: “Incontinentia pigmenti” -various severity from skin abnormality to CNS problems

  26. 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

  27. 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

  28. 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

  29. Pedigree Fundamentals

  30. Autosomal Recessive(it can be hidden and reappear)

  31. What inheritance pattern?

  32. Autosomal Dominant

  33. What inheritance pattern?

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

  35. What inheritance pattern?

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

  37. Any ideas on this one?

  38. Mitochondrial Inheritance(all children get mitochondria of mother)

  39. 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

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

  41. Different Prenatal Testing • MSAFP • (test mother’s blood) • Amniocentesis • CVS • Nuchal Fold- • sonogram measures amount of fluid in fetus’ dorsal neck

  42. Maternal Serum Screen

  43. Neural Tube Defects

  44. CVS – Chorionic Villi Sampling Amniocentesis Diagnostic Testing

  45. Case 1 • Mother is 28 years old • Maternal Serum Screen indicates 1/30 for Down Syndrome

  46. Teratogens • Thalidomide • Medications for maternal illness

  47. Osteogenesis Imperfecta

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