Term
| What are Mendellian/Monogenic laws of inheritance? |
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Definition
| Principles of inheritance of single-gene disorders are the same that govern the inheritance of other traits, such as eye color. |
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Term
| Why do Mendelian patterns occur? |
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Definition
| These patterns occur because a single gene is defective and the disorders that result are referred to as monogenic or, sometimes, mendelian disorders. |
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Term
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Definition
| If the defect occurs on the autosome, the genetic disorder is termed autosomal; if the defect is on the X chromosome, the genetic disorder is termed X-linked. |
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Term
| How are defects classified? |
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Definition
The defect also can be classified as dominant or recessive.
Monogenic disorders include autosomal dominant, autosomal recessive, X-linked dominant, and X-linked recessive. |
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Term
| What is an Autosomal Dominant Inheritance Pattern? |
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Definition
Normal Mother/ Affected Father
50% chance of no defect/50% chance there is |
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Term
| What is Autosomal Recessive Inheritance Pattern? |
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Definition
Carrier Mother/Carrier Father
Normal Male/Carrier Female/Carrier Male/Affected Female |
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Term
Is the following statement true or false?
According to the pattern of autosomal recessive inheritance, a carrier is a person who inherits one normal gene and one abnormal gene from parents who are both carriers. |
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Definition
True. According to the pattern of autosomal recessive inheritance, a carrier is a person who inherits one normal gene and one abnormal gene from parents who are both carriers.
Rationale: Offspring of two carriers of the abnormal gene have a 25% chance of inheriting two normal genes; a 50% chance of inheriting one normal gene and one abnormal gene (carrier); and a 25% chance of inheriting two abnormal genes (and, thus, the disorder). |
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Term
| What are the goals of the human genome project? |
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Definition
Identify all of the approximately 20,000 to 25,000 genes in human DNA
Determine the sequences of the 3 billion chemical base pairs that make up human DNA
Store this information in databases to make it accessible for further study
Improve tools for data analysis
Transfer related technologies to the private sector
Address the ethical, legal, and social implications of this discovery |
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Term
| What are the Ethical and Legal Issues Related to Genetic Risk Profiling? |
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Definition
Patient privacy and confidentiality related to workplace discrimination
Access to health care
Issues of autonomy |
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Term
| What are the Laboratory and Diagnostic Tests for Down Syndrome? |
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Definition
Echocardiogram: to detect cardiac defects
Vision and hearing screening: to detect vision and hearing impairments
Thyroid hormone level: to detect thyroid disease
Cervical radiographs: to assess for atlantoaxial instability
Ultrasound: to assess for gastrointestinal malformations |
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Term
| What are the Common Disorders Influenced by Genetic Factors? |
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Definition
Birth defects
Chromosomal abnormalities
Neurocutaneous disorders
Intellectual disability
Short stature disorders
Connective tissue disorders
Inborn errors of metabolism |
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Term
| What are the autosomal dominant genetic disorders? |
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Definition
Neurofibromatosis
Huntington disease
Achondroplasia
Polycystic kidney disease |
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Term
| What are the autosomal recessive genetic disoders? |
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Definition
Cystic fibrosis
Phenylketonuria
Tay-Sachs
Sickle cell disease |
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Term
| What are the X-linked recessive genetic disorders? |
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Definition
Hemophilia
Color blindness
Duchenne muscular dystrophy |
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Term
| What are the multifactoral genetic disorders? |
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Definition
Cleft lip and cleft palate
Spina bifida
Pyloric stenosis
Clubfoot
Congenital hip dysplasia
Cardiac defects |
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Term
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Definition
Only one copy of a particular chromosome instead of the usual pair
All fetuses spontaneously abort in early pregnancy; survival occurs only in mosaic forms of these disorders. |
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Term
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Definition
Three of a particular chromosome instead of the usual two
Most common trisomies include trisomy 21 (Down syndrome), trisomy 18, and trisomy 13. |
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Term
| What are the Significant Findings in Medical History of a Child With a Genetic Disorder? |
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Definition
Maternal age older than 35 years or paternal age older than 50
Repeated premature births, breech delivery
Congenital hip dysplasia
Abnormalities found on ultrasound or in prenatal blood screening tests
Amniotic fluid abnormalities
Multiple births
Exposure to medications and known teratogens
Decreased fetal movement |
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Term
| What are the rapid genetic advancements occurring? |
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Definition
Increased awareness
Still a rare occurrence
2% have major malformations
Of these, 80% have genetic cause & risk of recurrence
43% of genetic disorders dx early
82% before 6 months of age |
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Term
| What are the Potential for Genetic Problems? |
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Definition
Family history
Birth defects
Mental retardation
Familial conditions
Fetal exposure to teratogens
Ethnic background |
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Term
| What is the chance of a female carrier passing Hemophelia A (x-linked recessive) onto your children? |
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Definition
25% risk of having an affected son
25% risk of having a carrier daughter
25% chance of non-carrier daughter
25% chance of healthy son
Mendelian Distribution |
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Term
| What are the typical effects of Hemophelia A? |
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Definition
Phenotypically normal at birth
Bleeding tendency ranges:
Spontaneous bleeding
Bleeding after trauma |
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Term
| What are the indications for genetic evaluation? |
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Definition
Chromosomal abnormality
Birth defects
Mental retardation/language disabilities
Developmental delay
Subtle dysmorphic features |
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Term
| What are the specific single gene disorders? |
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Definition
Cystic fibrosis
Duchenne muscular dystrophy
Fragile X syndrome
Hemophilia
Sickle cell disease
Spinal muscular atrophy
Tay-Sachs disease
Thalassemia |
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Term
| What do the Presentation specific to genetic disorders may include? |
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Definition
Dysmorphic features
Developmental delay
Normal intelligence to mental retardation
Short stature
Failure to thrive
Progressive deterioration
Seizures |
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Term
| What is a genetic pedigree history? |
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Definition
Obtain 3 generation family history
Family members
Abnormalities
Gestational age
Miscarriages & stillbirths
Health & mental status of each
Aim at specific disorder
Current age |
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Term
| What is chorionic villus sampling? |
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Definition
8-12 weeks gestation
Chromosomal
Biochemical
DNA |
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Term
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Definition
11-14 weeks (early diagnosis)
15-18 weeks (second trimester dx)
Test same as for CVS |
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Term
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Definition
Throughout pregnancy
Fetal structures (best seen > 12 weeks) |
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Term
| What is a -fetoprotein (AFP) screen? |
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Definition
After 14 weeks gestation
= fetal neural tube or body wall defect
= risk for Down syndrome |
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Term
| What does triple screening test levels of? |
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Definition
AFP
human chorionic gonadotropin (HCG)
Estriol |
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Term
| What does triple screening test FOR? |
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Definition
Down syndrome
Trisomy 18
Other chromosome abnormalities |
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Term
| What is an Acetylcholinesterase test? |
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Definition
> 14 weeks gestation
=Neural tube |
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Term
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Definition
2nd trimester
Test for same as CVS using fetal blood |
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Term
| What is precutatneous umbilical blood sampling? |
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Definition
2nd trimester test
Same as for fetoscopy |
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Term
| What are the risk factors/problem w/ down syndrome? |
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Definition
Presence of third #21 chromosome
Occurs in 1:660 births
Increased maternal age
increases risk
Degree of retardation ranges
Premature aging |
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Term
| What are the physical findings of Down's Syndrome? |
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Definition
Microcephaly
Flattened nose
Protruding tongue
Inner epicanthal folds
Upward slanting eyes
Short broad hands/fingers
Delayed growth/development
Hypotonia
Microcephaly
Flattened nose
Hypertelorism
Protruding tongue
Inner epicanthal Folds
Upward slanting eyes
Hypertelorism (widely separated eyes) & hypotelorism (narrowly separated eyes): diagnosis should be based on measurement of the intercantal distance (B). On average this distance is 2.0 cm but can range from 1.5 to 2.5 cm. In someone who has epicanthal folds (such as in a Down’s syndrome baby) use measurement A or C. The average measurement for A is 6.5 cm and for c it is 4.0 cm. Ranges from 5.5 to 7.5 cm, and for C the range is from 3 to 4.5 cm. |
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Term
| What is important to note about hand creases in down's |
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Definition
Many people think about semien crease when thinking about Down’s syndrome but this is not a very reliable indicator of the syndrome.
Bilateral more likely Down’s
About 10% of the population have this crease and are normal
How do creases develop? In utero with amniotic fluid
If active - less chance
If inactive (hypotonic) - more chance
Short broad hands/fingers
Single palmer crease
Hypotonia |
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Term
| What are other possible manifestations that are found with Down Syndrome? |
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Definition
Seizures
Congenital heart disease
Endocrine abnormalities
Esophageal/duodenal atresia
Hearing/vision impairment
Obesity
Leukemia |
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Term
| What is Fragile X Syndrome? |
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Definition
Change in long arm of X chromosome
Occurs in 1:2000 males
Occurs in 1:4000 females
25% of male asymtomatic carriers
Most common form of inherited mental retardation |
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Term
| What are the typical findings of Fragile X Syndrome? |
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Definition
Large forehead/ prominent jaw
Macro-orchidism
Avoidance of eye contact
Developmental delay
Poor motor coordination
Hyperactivity
Seizures (in up to 50%) |
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Term
| What is Klinefelter Syndrome? |
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Definition
Involves only males
Extra X chromosome
Appears normal at birth
Occurs in 1:1000 males
Syndrome apparent at puberty
Hypogonadasm
Infertility
Not inherited |
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Term
| What are the typical manifestations of Klinefelter Syndrome? |
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Definition
Tall stature
Simian crease
Abnormal body proportions
Underdeveloped secondary sexual characteristics
Gynecomastia
Learning disability
Personality impairment |
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Term
| What is the be noted about picture on slide 41? |
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Definition
| Note the increased height (175 cm, >95% for age), also has abnormally long legs - lanky, feminine distribution of pubic hair, absence of chest, axillary or facial hair and small penis & testes. |
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Term
| What is Trisomy 18 (Edward's Syndrome)? |
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Definition
Occurs in 1:3000 births
Affects girls more often than boys
Majority die before age 1
May be diagnosed in utero |
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Term
| What are the typical manifestations of Trisomy 18 (Edward's Syndrome)? |
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Definition
Prenatal history: uterus unusually large
Low birth weight
Microcephaly
Low set ears
Micrognathia
Crytorchidism
Hernias
Congenital heart disease
Kidney abnormalities
Ophthalmic manifestations
Mental retardation |
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Term
| What are the physical manifestations in the baby of Trisomy 18? |
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Definition
High Pitched Shrill Cry, Decerebrate/Decorticate Posturing
Small head, legs crossed, high-pitched scream, and arched back |
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Term
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Definition
| Trisomy 13 (also called Patau syndrome) is a genetic disorder in which a person has three copies of genetic material from chromosome 13, instead of the usual two copies. Rarely, the extra material may be attached to another chromosome (translocation). |
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Term
| Is trisomy 13 partial or full? |
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Definition
Partial trisomy -- the presence of a part of an extra chromosome 13 in the cells.
The extra material interferes with normal development. |
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Term
| What are the symptoms of trisomy 13? |
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Definition
Cleft lip or palate
Clenched hands (with outer fingers on top of the inner fingers)
Close-set eyes -- eyes may actually fuse together into one
Decreased muscle tone
Extra fingers or toes (polydactyly)
Hernias: umbilical hernia, inguinal hernia
Hole, split, or cleft in the iris (coloboma)
Low-set ears
Intellectual disability, severe
Scalp defects (missing skin)
Seizures
Single palmar crease
Skeletal (limb) abnormalities
Small eyes
Small head (microcephaly)
Small lower jaw (micrognathia)
Undescended testicle (cryptorchidism) |
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Term
| What is a cleft lip/palate? |
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Definition
Cleft lip and cleft palate are birth defects that occur when a baby’s lip or mouth do not form properly during pregnancy. Together, these birth defects commonly are called “orofacial clefts”. These birth defects happen early during pregnancy. A baby can have a cleft lip, a cleft palate, or both a cleft lip and cleft palate.
The lip forms between the fourth and seventh weeks of pregnancy. A cleft lip happens if the tissue that makes up the lip does not join completely before birth. This results in an opening in the upper lip. The opening in the lip can be a small slit or it can be a large opening that goes through the lip into the nose. A cleft lip can be on one or both sides of the lip or in the middle of the lip, which occurs very rarely. Children with a cleft lip also can have a cleft palate. |
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Term
| What causes cleft lip/palate? |
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Definition
The causes of orofacial clefts among most infants are unknown. Some children have a cleft lip or cleft palate because of changes in their genes. Cleft lip and cleft palate are thought to be caused by a combination of genes and other factors, such as things the mother comes in contact with in her environment, or what the mother eats or drinks, or certain medications she uses during pregnancy.
Smoking―Women who smoke during pregnancy are more likely to have a baby with an orofacial cleft than women who do not smoke.
Diabetes―Women with diabetes diagnosed before pregnancy have an increased risk of having a child with a cleft lip with or without cleft palate, compared to women who did not have diabetes.
Use of certain medicines―Women who used certain medicines to treat epilepsy, such as topiramate or valproic acid, during the first trimester (the first 3 months) of pregnancy have an increased risk of having a baby with cleft lip with or without cleft palate. |
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Term
| What is Turner's Syndrome? |
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Definition
XO Karyotype
Occurs in 1:2000 live births
Most common sex-linked chromosome anomaly in females
Many embryos do not survive to term (95%) |
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Term
| WHat are the typical manifestations of Turner's Syndrome? |
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Definition
Lymphedema
Webbed neck
Low hairline
Learning disabilities
Lack of secondary sex characteristics
Shield shaped chest
Head/neck abnormalities
Hypertension
Juvenile-form hypothyroidism - Hashimotos |
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Term
Which of the following ongoing assessments is of low priority for individuals with Turner’s syndrome?
A. Cardiac monitoring
B. Vision screening
C. Tanner staging
D. Thyroid screening |
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Definition
| Correct answer: “B”---girls with Turner’s are at risk for coarctation of the aorta, Hashimoto’s thyroiditis, and delayed development of secondary sexual characterisitcs |
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Term
Of the following which is associated with Fragile X syndrome but not Turner’s syndrome?
A. Autism
B. Delayed puberty
C. Short Stature
D. Obesity |
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Definition
| Correct Answer: “A”—7% of those with Fragile X syndrome also are autistic. Turner’s syndrome children are more susceptible to developing short stature and delayed puberty. Obesity is a condition of those with Prader Willi syndrome |
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Term
| What is sickle cell anemia? |
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Definition
Sickle cell anemia is the most common form of sickle cell disease (SCD). SCD is a serious disorder in which the body makes sickle-shaped red blood cells. “Sickle-shaped” means that the red blood cells are shaped like a crescent.
Sickle cells contain abnormal hemoglobin called sickle hemoglobin or hemoglobin S. Sickle hemoglobin causes the cells to develop a sickle, or crescent, shape.
Sickle cells are stiff and sticky. They tend to block blood flow in the blood vessels of the limbs and organs. Blocked blood flow can cause pain and organ damage. It can also raise the risk for infection. |
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Term
| Who is sickle cell common in? |
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Definition
African Americans
Sickle cell anemia is an inherited, lifelong disease. People who have the disease are born with it. They inherit two genes for sickle hemoglobin—one from each parent. |
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Term
| What is sickle cell trait? |
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Definition
| People who inherit a sickle hemoglobin gene from one parent and a normal gene from the other parent have a condition called sickle cell trait. |
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Term
| What is the difference between sickle cell and sickle cell trait? |
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Definition
| Sickle cell trait is different than sickle cell anemia. People who have sickle cell trait don't have the disease. Like people who have sickle cell anemia, people who have sickle cell trait can pass the sickle hemoglobin gene to their children. |
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Term
| What is the outlook for sickle cell anemia? |
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Definition
Sickle cell anemia varies from person to person. Some people who have the disease have chronic (long-term) pain or fatigue (tiredness). However, with proper care and treatment, many people who have the disease can have improved quality of life and reasonable health much of the time.
Because of improved treatments and care, people who have sickle cell anemia are now living into their forties or fifties, or longer. |
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