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Oral Pathology > LO 7 > Flashcards

LO 7 Flashcards

1
Q

Define genetics

A

The inheritance and expression of inherited traits

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2
Q

Define syndrome

A

A distinctive association of signs and symptoms occurring together

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3
Q

Define phenotype

A

The physical, biochemical, and physiologic traits of an individual

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4
Q

Define genes

A

The hereditary units transmitted from one generation to another

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5
Q

Describe chromosomes

A
  1. The small bodies in the nucleus of a cell that carry the chemical instructions for reproduction of the cell in addition to other cellular functions
  2. Chromosomes contain DNA, which directs the production of amino acids, polypeptides, and proteins by the cell
  3. DNA has the ability to duplicate itself
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6
Q

Describe autosomes versus sex chromosomes

A
  1. Chromosomes 1 through 22 are known as the autosomal chromosomes (autosomes)
  2. Humans have 23 paired chromosomes= 46 in total
  3. 23rd set of chromosomes in human cells are the sex chromosomes - X/Y
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7
Q

Describe mitosis

A
  1. The process of cellular division in a somatic cell during a part of the cell’s life span called the mitotic cycle
  2. Prophase, Metaphase, Anaphase, Telophase
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8
Q

Describe meiosis

A

The two-step cellular division of the primitive (original) germ cells, which reduces the number of chromosomes by half and produces mature germ cells or gametes

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9
Q

Describe the phases of mitosis

A
  1. Prophase - The chromosomes are lining up toward metaphase
  2. Metaphase - Chromosomes at the equatorial plane of the cell; Long and short arms are joined at the centromere; Each identical half is called a chromatid
  3. Anaphase - The chromatids are in the process of splitting
  4. Telophase - Cytokinesis- two daughter cells are formed
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10
Q

Define diploid

A

Having two sets of chromosomes

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11
Q

Define haploid

A

Having a single set of chromosomes - Gametes (sex cells) are called haploid

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12
Q

Describe first meiosis

A
  1. The members of each pair of chromosomes line up and exchange segments at contacts known as chiasmata
  2. The chromosomes separate, but no splitting of the centromere occurs
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13
Q

Describe nondisjunction

A
  1. Occurs during first meiosis
  2. Occasionally, both chromosomes that were crossing over do not separate, and both migrate to the same cell
  3. E.g. Down syndrome (trisomy 21) - Three of chromosome 21 are found instead of two
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14
Q

Describe second meiosis

A
  1. Essentially a mitotic division
  2. Each chromosome splits longitudinally
  3. No replication of DNA occurs before the second meiosis
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15
Q

Describe DNA

A
  1. Deoxyribonucleic acid
  2. Contains the template that carries all genetic information
  3. Double stranded
  4. DNA is transcribed into ribonucleic acid (RNA) - Single stranded, ready for duplication
  5. The bases form chains that are coiled to form the double helix
  6. A sequence of three bases is called a codon - encodes an amino acid
  7. Several amino acids form a polypeptide, and one or more polypeptides form a protein
  8. Mitochondrial DNA is maternally inherited - It is passed from maternal genome to offspring regardless of sex
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16
Q

What is a nucleotide?

A
  1. The basic unit of DNA
  2. Nitrogen-containing base
  3. Five-carbon sugar (deoxyribose)
  4. Phosphate
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17
Q

What are the 4 bases found in DNA?

A
  1. Adenine
  2. Guanine
  3. Thymine
  4. Cytosine
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18
Q

Describe RNA

A
  1. Ribonucleic Acid
  2. The genetic code contained in DNA is transcribed into RNA
  3. RNA is a single strand
  4. Its sugar is a ribose rather than the deoxyribose of DNA
  5. The base uracil replaces thymine in DNA - The base Uracil (U) is found in RNA, replaces (T)
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19
Q

What are the 4 types of RNA?

A
  1. Messenger RNA (mRNA) - Blueprint for coding of proteins
  2. Transfer RNA (tRNA) - Transfers amino acids from the cytoplasm to the mRNA
  3. Ribosomal RNA (rRNA) - Combines with several polypeptides to form ribosomes
  4. Heterogeneous nuclear RNA (hnRNA) - The precursor to mRNA, found within the nucleus
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20
Q

Describe alleles

A
  1. The genes that are located at the same level (locus) in homologous chromosomes and that dictate the same functions or characteristics
  2. When allelic genes are identical, the person is homozygous for that gene
  3. When allelic genes are different, the person is heterozygous for that gene
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21
Q

Describe dominant genes

A

A trait or characteristic that manifests when it is carried by only one of a pair of homologous chromosomes

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22
Q

Describe recessive genes

A

A trait or characteristic that manifests clinically with a double gene dose in autosomal chromosomes or with a single dose in males if the trait is X-linked

23
Q

Describe Molecular Chromosomal Abnormalities

A
  1. Occur at the DNA level
  2. Not detectable microscopically
  3. Most inherited disorders are at the level of one or both allelic genes
24
Q

Describe gross Chromosomal Abnormalities

A
  1. Can be observed in a karyotype: A photographic representation of a person’s chromosomal constitution
  2. Alterations in chromosome number: Nondisjunction
  3. Aneuploid: Any extra number of chromosomes that is not an exact multiple
  4. Alterations in chromosome structure
25
Q

List the possible alterations in chromosome structure

A
  1. Deletion
  2. Translocation
  3. Inversion
  4. Duplication
26
Q

List Clinical Syndromes Resulting from Gross Chromosomal Abnormalities

A
  1. Trisomy 21
  2. Trisomy 13
  3. Turner syndrome
  4. Klinefelter syndrome
27
Q

Describe Trisomy 21: Down Syndrome

A
  1. Associated with late maternal age
  2. Slanted eyes
  3. Shorter stature
  4. Heart abnormalities
  5. Intellectual challenges
  6. Fissured tongue
  7. Gingival and periodontal disease has been reported in 90% of affected individuals
  8. Hypodontia
  9. Abnormally shaped teeth
  10. Anomalies in eruption with malposition and crowding of teeth are common
28
Q

Describe Trisomy 13

A
  1. Multiple abnormalities in various organs
  2. 70% of afflicted persons die within the first 7 months of life
  3. Characteristic facial clinical findings include: Bilateral cleft lip and palate
29
Q

Describe Turner Syndrome

A
  1. Missing of of the ‘X’ chromosomes, only one present
  2. Female karyotype
  3. Short stature
  4. Webbing of the neck
  5. Edema of the hands and feet
  6. Low hairline on nape of neck
  7. Broad chest with wide-spaced nipples
  8. Abnormal aorta
  9. Sparse body hair
  10. Infantile external genitals
  11. Primary amenorrhea
30
Q

Describe Klinefelter Syndrome

A
  1. May be XXXY or XXXXY
  2. Most are from nondisjunction of the X chromosome
  3. Male phenotype
  4. Not detected clinically until puberty - Taller than average; Wide hips; Female pubic hair distribution; Development of breast tissue; Testes are smaller and harder
  5. The maxilla is slightly hypoplastic
31
Q

What are the possible patterns of inheritance?

A
  1. Autosomal-dominant inheritance
  2. Autosomal-recessive inheritance
  3. X-linked inheritance - Lyon hypothesis and X-linked recessive traits
  4. Genetic heterogeneity
  5. Examples of molecular chromosomal abnormalities
32
Q

Describe Autosomal-Dominant Inheritance

A
  1. Transmitted vertically from one generation to the next
  2. Males and females are equally affected
  3. Lack of penetrance: When an individual carries a gene without presenting any clinical manifestation.
  4. The person is a ‘carrier’ with heterozygous genes
33
Q

Describe Autosomal-Recessive Inheritance

A
  1. Individuals exhibiting an autosomal-recessive trait must be homozygous for the gene
  2. Both parents of the affected child must be carriers of the trait
34
Q

Describe X-linked Inheritance

A
  1. Women have two X chromosomes - They may be either heterozygous or homozygous for a gene that is located on the X chromosome
  2. Men have only one X and one Y chromosome - If a deleterious gene occurs on the X chromosome in a male, the condition or trait will be seen clinically regardless of the dominant or recessive behavior of the same gene in women
35
Q

Describe Genetic Heterogeneity

A
  1. Genetic heterogeneity: When a condition has more than one inheritance pattern as well as differences in the degree of clinical manifestations for each of the inherited varieties.
  2. E.g. hair colour
  3. Recessive: The person must be homozygous for the trait to be seen
36
Q

List Inherited Disorders Affecting
the Gingiva and Periodontium

A
  1. Cyclic neutropenia
  2. Gingival fibromatosis
  3. Laband syndrome
37
Q

Describe Cyclic Neutropenia

A
  1. An autosomal-dominant condition
  2. Characterized by a cyclic decrease in the number of circulating neutrophils
  3. Systemic manifestations include fever, malaise, sore throat, and occasional cutaneous infections
  4. Kostmann syndrome or chronic neutropenia: Autosomal-recessive condition

Oral manifestations
1. Severe ulcerative gingivitis
2. Gingivostomatitis
3. Ulcerations on tongue and oral mucosa
4. Repeated episodes lead to severe periodontal disease
5. Person is immunocompromised

38
Q

Describe Gingival Fibromatosis

A
  1. A component of several inherited syndromes
  2. Composed of very firm tissue with a granular corrugated surface
39
Q

Describe Laband Syndrome

A
  1. An autosomal-dominant inheritance pattern
  2. Characterized by: Gingival fibromatosis, Dysplastic or absent nails, Malformed nose and ears
40
Q

Describe Cleidocranial Dysplasia

A
  1. Autosomal dominant, but about half of the cases are isolated examples caused by spontaneous mutation or a gene with poor penetrance
  2. The fontanelles remain open and the cranium develops a mushroom shape
  3. The neck is long and narrow as a result of unilateral or bilateral hypoplasia of clavicles
  4. The premaxilla is generally underdeveloped, resulting in pseudoprognathism
  5. Patients have many supernumerary teeth, which are crowded in the jaws and do not erupt
  6. Multiple cysts can develop in association with impacted teeth
41
Q

Describe Osteogenesis Imperfecta

A
  1. Mutations occur that affect collagen, resulting in abnormally formed bones that fracture easily
  2. In mildest cases, individuals may only show blue sclera (that portion of the eye that is usually white)
  3. Microdontia
  4. Teeth appear opalescent or translucent but darken with age
  5. Enamel is lost because of abnormal dentin during formation stages
42
Q

Describe Torus Mandibularis

A

An autosomal-dominant inheritance pattern with variable expression and marked penetrance

43
Q

Describe Torus Palatinus

A

An autosomal-dominant inheritance pattern with variable expression and almost 100% penetrance

44
Q

Describe Maxillary Exostosis

A
  1. An autosomal-dominant inheritance pattern
  2. Occurs on the buccal aspect of the maxilla
  3. May be single, multiple, unilateral, or bilateral
45
Q

Describe Isolated Cleft Palate and Cleft
Lip With or Without Cleft Palate

A
  1. An autosomal-dominant inheritance pattern
  2. May occur as a component of a large number of syndromes
  3. Cleft lip-palate and congenital lip pits are the most common syndrome
46
Q

Describe Multiple Mucosal Neuroma
Syndrome (MEN 2B Syndrome)

A
  1. Multiple mucosal neuromas
  2. Medullary carcinoma of the thyroid gland
  3. Autosomal-dominant inheritance pattern

Characterized by:
1. Tall patients
2. Thick, large lips
3. Everted upper eyelids
4. Mucosal neuromas prominent on lips, tongue, buccal mucosa, and eyelids
5. Medullary carcinoma of thyroid
6. Skeletal abnormalities

47
Q

Describe Peutz-Jeghers Syndrome

A
  1. Autosomal dominant
  2. Characterized by - Multiple melanotic macular pigmentations; Gastrointestinal polyposis—hamartomas
47
Q

Describe White Sponge Nevus (Familial
White Folded Mucosal Dysplasia)

A
  1. An autosomal-dominant inheritance pattern with complete penetration

Characterized by:
1. White, corrugated, soft, folding buccal oral mucosa
2. Thick layer of keratin that desquamates and leaves a raw mucosal surface
3. Free gingiva is not affected
4. Often confused with lichen planus

48
Q

Describe Amelogenesis Imperfecta

A
  1. A group of inherited conditions affecting the enamel of teeth with no associated systemic defects
  2. The tooth enamel does not develop to a normal thickness/constitution
  3. Enamel is weak and will ‘flake’ off, Ultrasonic use is contraindicated
  4. Some severe than enamel hypoplasia
  5. Caries risk should be evaluated
49
Q

Describe Dentinogenesis Imperfecta

A
  1. Multiple types
  2. Associated with osteogenesis imperfecta
  3. Hereditary opalescent dentin
  4. No pulp chambers or root canals are seen
  5. Roots are short and thin with periapical radiolucencies
50
Q

Describe Dentin Dysplasia

A
  1. Autosomal dominant
  2. Type I: Radicular - The teeth have normal crowns and abnormal roots; The teeth are generally exfoliated prematurely
  3. Type II: Coronal - Primary teeth are translucent with an amber color; Adult teeth appear normal
51
Q

Describe Hypophosphatemic
Vitamin D–Resistant Rickets

A
  1. An X-linked dominant inheritance pattern
  2. Low serum levels of phosphorus
  3. Large pulp chambers with very long pulp horns
  4. Dentin has pronounced cracks, which leads to pulpal infections
52
Q

Describe Pegged or Absent Maxillary
Lateral Incisors

A
  1. An autosomal-dominant inheritance pattern with variable expression
  2. Lateral incisors may be small, peg shaped, or congenitally missing

Oral Pathology (11 decks)

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