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Genetics > Chapter 9 > Flashcards

Chapter 9 Flashcards

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1
Q

Dysmorphology

A

-(dys= “painful”; morph = “shape”)
-defined as the study of congenital anomalies in the form or body parts of a person or abnormal patterns of development.

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2
Q

Hypertelorism

A

Widely spaced eyes

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3
Q

Ptosis

A

Drooping eyelids

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4
Q

Major anamolies

A

Serious
Require medical or surgical attention
Can have life-threatening implications

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5
Q

Minor anomaly

A

No serious functional or cosmetic consequences, which may or may not be surgically corrected.

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6
Q

Clinodactyly

A

Laterally curved digit

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7
Q

Malformation

A

-caused by a primary problem in the growth or development of a particular tissue. For example, cleft lip/palate.
-developmental problem during formation
-

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8
Q

Deformation

A

-caused by the effect of a physical or mechanical force that prevents the proper growth of a structure that would have developed normally.
-embryo or fetus may be perfectly fine, but something is preventing it from growing properly.
-Constriction in the uterus is one possible cause. The correction of deformations ofren occurs after the mechanical stressor is removed. If removing the stressor does not correct the problem, clinicians start to consider the possibility that the structure was not properly formed.

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9
Q

oligohydramnios

A

State of not having enough amniotic fluid

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10
Q

Disruption

A

-In a disruption, a normal developmental process is “dis- rupted” by some event that leads to the destruction of normal tissue. For example, exposure ro certain drugs can cause a disruption, as can trauma or vascular insufficiency. It is different from a malformation because everything started out normally.

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11
Q

Syndrome

A

a collection of features that occur together and have a consistent pattern. They are thought to have the same cause.

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12
Q

Sequence

A

-one anomaly starts a chain reaction that causes another problem that then causes another and then sometimes another.
-chain of events that starts with one problem.
-One example is Pierre-Robin (pronounced “Roban”) sequence. The anomaly that starts out Pierre-Robin is micrognathia (a small jaw, which is caused by shortening and narrowing of the mandible) in the developing fetus (Fig. 9-3). Sometimes the word ret- rognathia is used to indicate that the jaw is moved posteriorly (and may be accompanied by micrognathia). This small jaw causes the tongue to be positioned backward into the pharynx (glossoptosis). The posteriorly positioned tongue can cause a cleft palate and sometimes respiratory obstruction. It is a sequence of events that started with the poorly formed jaw

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13
Q

Association

A

-a collection of features occurs together, but the relationship is not clear

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14
Q

Gestalt

A

Sometimes, particularly when looking at facial and developmental features, experts in clinical genetics talk about getting a sense of the whole pattern or picture of the patient. The term gestalt is used to convey this overall impression. Being able to appreciate the gestalt comes from much experience working with patients who have anomalies and with their families.

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15
Q

Teratogens

A

Substances that can alter development and can cause a birth defect

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16
Q

Marfan syndrome phenotype

A

long fingers and toes

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17
Q

Table 9-1
Selected Named Genetic Disorders That Can Cause Cognitive Impairment and Associated Common Dysmorphic Features

A
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18
Q

Hyperphagia

A

Excessive eating

19
Q

Midface hypoplasia

A

Central part of the face, including upper jaw, cheeks, and eye region, is small in proportion to the rest of the face

20
Q

Frontal bossing

A

Describes a very large forehead with bilateral bulging of the frontal bone prominences

21
Q

Craniofacial abnormalities

A

Variations from the usual formation of the skull and face

22
Q

Plagiocephaly

A

significant asymmetry of the skull. It can be caused by the way a newborn is positioned during sleep, which is called positional molding.

23
Q

Craniosynostosis

A

-ccurs when more than one of the cranial sutures fuse together earlier than they should. If several sutures dose toO early, the brain may not have room to grow, and intracranial pressure will increase (Reardon, 2008). This is a serious medical problem that requires urgent surgical attention.

24
Q

Macrocephaly

A

“enlarged head,” and, even though it is easy to define, exactly what makes a head seem unusually large is much less clear. The technical definition is a cranium with an occipitofrontal circumference greater than the 97th percentile compared with others of the same age and gender

25
Q

Microcephaly

A

-means that the head is smaller than expected. It is generally defined clinically as having a head circumference that is more than two standard deviations below what is expected for the child’s age and gender
-Microcephaly is an important finding, suggesting that the brain has grown abnormally. This may be caused by structural abnormalities or by a neurodegenerative process in the brain, or the small head circumference could just run in the family and have no consequence. Microcephaly can occur alone, with no other abnormal features, as an autosomal-recessive condition.

26
Q

syndactyly

A

(partial fusing of the digits)

27
Q

Micrognathia

A

describe the appearance of a recessed chin caused by an unusually small mandible.

28
Q

telecanthus

A

the distance between the inner canthi might be abnormally wide, but the interpupillary and outer canthi distances are within normal range. Although this situation resembles hypertelorism,

29
Q

hypotelorism

A

the eyes are much closer together than would be expected for the body size and age of the child

30
Q

palpebral fissure

A

The space between the eyelids of each eye.

31
Q

Lip pits

A

symmetrical depressions in the lip, usually in the part of the lower lip called the vermilion (the area that is somewhat redder than the skin surrounding it).

32
Q

Polydactyly

A

extra finger or toe.

33
Q

brachydactyly

A

fingers or toes are short and are not in proportion ro the rest of the body,

34
Q

syndactyly

A

-When fingers (or toes) are partially or completely fused together
-It can affect only the skin and soft tissues (simple), or it can involve the bone as well (complex). Syndactyly occurs when the fingers or toes do not separate into individual digits during embryonic development.

35
Q

hypermobile or hyperexrensible

A

-joints are considered hypermobile or hyperexrensible when they have a greater range of motion than what is commonly seen at a given age.
-Women are twice as likely as men to be hyperexrensible. However, hyperextensibiliry is also associated with disorders like Ehlers-Danlos syndrome and is an important assessment finding.

36
Q

SUMMARY

A

-Dysmorphology assessment is a key tool for syndrome/disorder identification by genetics professionals. Although thoroughly and accurately assessing for dysmorphic features takes lots of practice and bedside experience, nurses can use their assessment skills to screen and refer people who may have a genetic condition. This chapter provides a brief overview of important concepts in dysmorphology and some of the more frequently recognized dysmorphic features. The health-care professional not specializing in genetics must be objective and accurate in describing anatomic variations and referring concerns to those professionals with the education and experience to complete a comprehensive assessment and make an accurate diagnosis.
• Dysmorphology focuses on the identification of abnormal features and their connection to genetic
conditions.
• Congenital anomalies can be classified as major anomalies, which usually require intervention, and
minor anomalies, which usually do not require intervention.
• Having one minor anomaly does not mean a person has a genetic problem.
• The four causes of congenital anomalies are as follows:
• Malformations, which are caused by an abnormal developmental process
• Deformations, which are caused by compression from mechanical forces
• Disruptions, which are caused by a disturbance in the normal developmental process
• Dysplasia, which is an alteration in the size and shape and organization of cells
• A syndrome is a collection of symptoms that all come from the same cause, whereas a sequence is a chain
of symptoms in which each one causes the next.
• Pierre-Robin is an example of a sequence that begins with micrognathia and ofren results in cleft palate
and airway obstruction.
• In addition to individual features, the clinician’s overall impression of the patient’s appearance (gestalt)
is important.
• Viewing the individual within the context of the family is important because some dysmorphic traits could just be benign family characteristics or could give further support for a possible genetic condition that has gone unrecognized in the family.
• More than 300 genetic disorders can cause cognitive impairment.
• Standard ways of measuring features have allowed clinicians to compare suspected dysmorphology
against age-related norms.
• Some features, such as low-set ears, are seen in many different genetic disorders as well as in people
who do not have a genetic disorder. They are considered nonspecific.

37
Q

Isaac is an 8-year-old boy who has been diagnosed with Treacher Collins syndrome (TCS). which can be transmitted as either an autosomal-dominant or autosomal-recessive condition depending on the gene involved. Isaac has micrognathia (small chin and jaw). and his cheekbones and other facial bones appear underdeveloped. His eyes slant downward. and he has very small ears. His parents are most concerned about his dentition. His teeth are very crooked. Issac is bright and is doing well in school. He has one brother who shares similar facial features but has problems with snoring and significant hearing loss. The boys have two sisters who do not appear to have any facial dysmorphology. The boys’ mother has slightly downslanted eyes and no other noticeable anomalies.
1. Provide an explanation for the differing phenotype among the family members described in this study.
2. Are the sisters affected or unaffected? How would you know? Is their sex a factor in whether they would be affected?
3. If TCS is being transmitted in an autosomal-dominant fashion in this family, what is the risk that another sibling would be affected?
4. Explain whyTCS is considered a syndrome and not a sequence.

A
38
Q
  1. What term is used to describe the condition of a child who has several dysmorphic features that are related to a single known genetic cause?
    a. Sequence
    b. Disruption
    c. Syndrome
    d. Malformation
A

C

39
Q
  1. Which characteristic or feature distinguishes a major anomaly from a minor anomaly?
    a. Major anomalies affect tissue structure, and minor anomalies affect tissue function.
    b. Minor anomalies affect tissue Structure, and major anomalies affect tissue function.
    c. Minor anomalies occur in external tissues, and major anomalies occur in internal tissues.
    d. Major anomalies require medical attention, whereas minor anomalies are considered a variation
    in structure.
A

D

40
Q
  1. Which term is used to describe an anomaly caused by a physical or mechanical force that prevents the proper growth of a Structure that would have developed normally if the force was nor present?
    a. Dysplasia
    h. Disruption
    c. Deformation
    d. Malformation
A

C

41
Q
  1. Which types of problems are more likely to be caused by a chromosomal abnormality?
    a. Single structural anomalies
    h. Deformations
    c. Syndromes
    d. Dysplasias
A

C

42
Q
  1. How is a sequence different from a syndrome?
    a.A sequence is usually caused by a single gene mutation, and a syndrome is always caused by a chromosomal abnormality.
    b. A syndrome is usually caused by a single gene mutation, and a sequence is always caused by a chromosomal abnormality.
    c. In a syndrome, one structural problem leads to the development of other problems, whereas a sequence is a collection of separate but consistent anomalies.
    d. In a sequence, one structural problem leads to the development of other problems, whereas a syndrome is a collection of separate but consisrenr anomalies.
A

D

43
Q
  1. Which statement regarding the phenotype of fetal alcohol spectrum disorder (FASD) is correct?
    a. Genetic and environmental factors influence the FASD phenotype.
    B. The malformarions in the phenotype of FASD represent a sequence.
    c. The genotype of FASD accurately predicts the phenotype of FASD.
    d. The phenotype of FASD accurately predicts the genotype of FASD.
A

A

Genetics (21 decks)

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