Genetics

Question 1

What is a syndrome?

Answer 1

A set of signs and/or symptoms occurring together in the same patient.

Question 2

How many chromosomes do humans have?

Answer 2

46 total (23 pairs), with 23 inherited from each parent.

Question 3

What is the genome?

Answer 3

The collection of all genes in the body; every nucleated cell contains the entire genome.

Question 4

What is the difference between DNA and RNA?

Answer 4

DNA is a double-stranded genetic template, while RNA is single-stranded and transcribes genetic information to build proteins.

Question 5

What is mitosis?

Answer 5

The division of somatic cells, producing two identical daughter cells.

Question 6

What is meiosis?

Answer 6

A two-step division process that creates gametes (sperm and egg), reducing chromosome number by half.

Question 7

What are alleles?

Answer 7

Different copies of the same gene located at the same position on paired chromosomes.

Question 8

What is the difference between genotype and phenotype?

Answer 8

Genotype is the genetic composition, and phenotype is the observable traits.

Question 9

What are Mendelian disorders?

Answer 9

Disorders caused by mutations in single genes, following autosomal dominant, autosomal recessive, or X-linked inheritance.

Question 10

What are chromosomal disorders?

Answer 10

Disorders caused by structural or numerical chromosome abnormalities, often influenced by environmental factors.

Question 11

What characterizes autosomal dominant inheritance?

Answer 11

A single mutated copy of the gene causes disease; affects males and females equally.

Question 12

What are examples of autosomal dominant disorders?

Answer 12

Huntington disease, neurofibromatosis, von Willebrand disease, osteogenesis imperfecta.

Question 13

What characterizes autosomal recessive inheritance?

Answer 13

Both copies of the gene must be mutated; males and females equally affected.

Question 14

What are examples of autosomal recessive disorders?

Answer 14

Cystic fibrosis, sickle cell anemia, Wilson disease.

Question 15

What characterizes X-linked inheritance?

Answer 15

The mutated gene is on the X chromosome; males are more frequently affected.

Question 16

What is the most common chromosomal disorder?

Answer 16

Down syndrome (Trisomy 21).

Question 17

What are examples of X-linked disorders?

Answer 17

X-linked recessive: Hemophilia; X-linked dominant: Vitamin-D resistant rickets.

Question 18

What causes Down syndrome?

Answer 18

An extra copy of chromosome 21.

Question 19

What are clinical features of Down syndrome?

Answer 19

Slanted eyes, short stature, heart abnormalities, variable intelligence, macroglossia, fissured tongue, hypodontia, crowding, gingival & periodontal disease.

Question 20

What is the karyotype for Down syndrome?

Answer 20

47, XX, +21 (or 47, XY, +21).

Question 21

What is the karyotype for Klinefelter syndrome?

Answer 21

47, XXY.

Question 22

What are clinical features of Klinefelter syndrome?

Answer 22

Male phenotype, gynecomastia (breast development), hypogonadism, and sterility.

Question 23

What is the karyotype for Turner syndrome?

Answer 23

45, X.

Question 24

What are clinical features of Turner syndrome?

Answer 24

Female phenotype, webbed neck, hypogonadism.

Question 25

What is the inheritance pattern of cyclic neutropenia?

Answer 25

Autosomal recessive.

Question 26

What characterizes cyclic neutropenia?

Answer 26

Cyclic decrease in neutrophils (~every 3 weeks) lasting 2-3 days.

Question 27

What are the oral manifestations of cyclic neutropenia?

Answer 27

Ulcerative gingivitis, periodontitis, oral ulcerations.

Question 28

Why is optimal oral hygiene important in cyclic neutropenia?

Answer 28

Reduces the risk of oral infections during neutropenic periods.

Question 29

What is the inheritance pattern of Papillon-Lefèvre syndrome?

Answer 29

Autosomal recessive.

Question 30

What are the key features of Papillon-Lefèvre syndrome?

Answer 30

Severe periodontal destruction, premature tooth loss, hyperkeratosis of palms & soles.

Question 31

What is gingival fibromatosis and what is the treatment?

Answer 31

A generalized, firm, fibrous gingival overgrowth. Treatment is Surgical reduction of gingival tissue.

Question 32

When does gingival fibromatosis typically present?

Answer 32

In childhood.

Question 33

What type of disorder is Ehlers-Danlos syndrome?

Answer 33

A group of inherited connective tissue disorders.

Question 34

What are the clinical features of Ehlers-Danlos syndrome?

Answer 34

Loose joints, hyperelastic skin, TMJ dysfunction, bruising, tooth abnormalities.

Question 35

What is the Gorlin sign in Ehlers-Danlos syndrome?

Answer 35

Ability to touch the tip of the tongue to the nose.

Question 36

What is the inheritance pattern of cherubism?

Answer 36

Autosomal dominant.

Question 37

What are the key clinical features of cherubism?

Answer 37

Bilateral facial swelling (ages 1-4), mandible most affected, eye displacement with maxillary lesions.

Question 38

What radiographic appearance is seen in cherubism?

Answer 38

Bilateral "soap bubble" multilocular radiolucencies.

Question 39

What does a biopsy of cherubism show?

Answer 39

Giant cell lesions.

Question 40

What is the inheritance pattern of Cleidocranial Dysplasia?

Answer 40

Autosomal dominant inheritance

Question 41

What bones are primarily affected in cleidocranial dysplasia?

Answer 41

Skull and clavicles.

Question 42

What is a key skeletal feature of cleidocranial dysplasia?

Answer 42

Underdeveloped or missing clavicles.

Question 43

What dental abnormality is common in cleidocranial dysplasia?

Answer 43

Many unerupted supernumerary teeth (pseudoanodontia).

Question 44

What is the inheritance pattern of Gardner syndrome?

Answer 44

Autosomal dominant inheritance

Question 45

What is a major risk associated with Gardner syndrome?

Answer 45

Colon polyps with 100% malignant transformation after 30 years of age.

Question 46

What jawbone abnormality is associated with Gardner syndrome?

Answer 46

Osteomas (benign bone overgrowths).

Question 47

What preventive treatment is recommended for Gardner syndrome?

Answer 47

Prophylactic colectomy.

Question 48

What is the inheritance pattern of Treacher Collins syndrome?

Answer 48

Autosomal dominant.

Question 49

What are the key facial abnormalities in Treacher Collins syndrome?

Answer 49

Hypoplastic mandible, high-arched palate, dental abnormalities, lower eyelid cleft (coloboma).

Question 50

What is the inheritance pattern of Gorlin Syndrome?

Answer 50

Autosomal dominant inheritance

Question 51

What are the key features of Gorlin syndrome?

Answer 51

Hypertelorism (wide-set eyes), basal cell carcinomas, multiple odontogenic keratocysts, bifid ribs.

Question 52

What is the treatment for Gorlin syndrome?

Answer 52

Surgical removal of basal cell carcinomas and jaw cysts.

Question 53

What is the inheritance pattern of Osteogenesis Imperfecta?

Answer 53

Autosomal dominant inheritance

Question 54

What is the primary defect in osteogenesis imperfecta?

Answer 54

Collagen defect leading to fragile bones and multiple fractures.

Question 55

What oral manifestation is seen in osteogenesis imperfecta?

Answer 55

Dentinogenesis imperfecta-like condition (opalescent teeth).

Question 56

Are primary or permanent teeth more affected in osteogenesis imperfecta?

Answer 56

Primary teeth (80%), permanent teeth (35%).

Question 57

Which is more common: cleft lip alone or cleft lip with cleft palate?

Answer 57

Cleft lip with cleft palate is twice as common as cleft lip alone.

Question 58

Are cleft lip and palate inherited?

Answer 58

They are multifactorial but can be part of inherited syndromes.

Question 59

What is a complete cleft lip?

Answer 59

A cleft that extends to the nostril.

Question 60

What is the treatment for cleft lip and cleft palate?

Answer 60

Surgical correction, sometimes combined with orthodontic procedures.

Question 61

What is the inheritance pattern of hereditary hemorrhagic telangiectasia?

Answer 61

Autosomal dominant.

Question 62

What are the oral signs of MEN2B?

Answer 62

Multiple mucosal neuromas on the lips and tongue.

Question 63

What are key features of hereditary hemorrhagic telangiectasia?

Answer 63

Dilated blood vessels on skin and mucosa, especially the tongue, and frequent nosebleeds (epistaxis).

Question 64

Why is this condition significant for dental hygiene procedures of hereditary hemorrhagic telangiectasia?

Answer 64

Oral lesions may bleed easily.

Question 65

What is the inheritance pattern of MEN2B?

Answer 65

Autosomal dominant inheritance

Question 66

What life-threatening condition is associated with MEN2B?

Answer 66

Medullary thyroid carcinoma.

Question 67

What is a preventative treatment for MEN2B?

Answer 67

Preventative thyroidectomy.

Question 68

What is the inheritance pattern of neurofibromatosis?

Answer 68

Autosomal dominant.

Question 69

Where do neurofibromas commonly occur in the oral cavity?

Answer 69

Tongue, gingiva, intraosseous areas.

Question 70

What is a potential risk associated with neurofibromas?

Answer 70

Some may become malignant.

Question 71

What skin feature is common in neurofibromatosis?

Answer 71

Café au lait pigmentation.

Question 72

What is the inheritance pattern of Peutz-Jeghers syndrome?

Answer 72

Autosomal dominant inheritance

Question 73

What are the key oral signs of Peutz-Jeghers syndrome?

Answer 73

Multiple melanotic macules on skin and mucosa.

Question 74

What gastrointestinal risk is associated with Peutz-Jeghers syndrome?

Answer 74

Polyposis with a high risk of developing cancer.

Question 75

What is the inheritance pattern of white sponge nevus?

Answer 75

Autosomal dominant.

Question 76

What are the oral manifestations of white sponge nevus?

Answer 76

White, corrugated, soft folded mucosa on bilateral buccal mucosa.

Question 77

What does amelogenesis imperfecta affect?

Answer 77

The enamel of teeth, with no systemic defects.

Question 78

What are the four types of amelogenesis imperfecta ?

Answer 78

Hypoplastic, hypocalcified, hypomaturation, hypoplastic-hypomaturation.

Question 79

What are the clinical features of dentinogenesis imperfecta type II?

Answer 79

Bulbous crowns, opalescent brown to brown-blue teeth.

Question 80

What is seen on a radiograph in dentinogenesis imperfecta type II?

Answer 80

No pulp chambers.

Question 81

Which teeth are more affected in dentinogenesis imperfecta type II?

Answer 81

Primary teeth are more severely affected than permanent teeth.

Question 82

What are the two types of dentin dysplasia?

Answer 82

Radicular and coronal.

Question 83

What are key features of radicular dentin dysplasia?

Answer 83

Normal crowns, abnormal roots, lack of pulp chambers.

Question 84

What are the three main features of ectodermal dysplasia?

Answer 84

Hypodontia (few teeth), hypotrichosis (sparse hair), hypohidrosis (reduced sweating).

Question 85

What is the genetic pattern of ectodermal dysplasia?

Answer 85

Genetic heterogeneity (mostly X-linked, some autosomal recessive).

Question 86

What are key features of coronal dentin dysplasia?

Answer 86

Translucent amber-colored primary teeth, thistle-shaped pulp chambers in permanent teeth.

Question 87

What enzyme is decreased in hypophosphatasia?

Answer 87

Serum alkaline phosphatase.

Question 88

What is a severe complication of ectodermal dysplasia?

Answer 88

Hyperthermia due to lack of sweat glands.

Question 89

What are key oral manifestations in hypophosphatasia?

Answer 89

Spontaneous premature shedding of teeth due to defective cementum.

Question 90

What are key skeletal features in hypophosphatasia?

Answer 90

Improper bone formation, rachitic-like changes, bowing of the legs, multiple fractures.

Question 91

What is the genetic pattern of hypophosphatasia?

Answer 91

Autosomal recessive inheritance