Genetics Flashcards
What is a syndrome?
A set of signs and/or symptoms occurring together in the same patient.
How many chromosomes do humans have?
46 total (23 pairs), with 23 inherited from each parent.
What is the genome?
The collection of all genes in the body; every nucleated cell contains the entire genome.
What is the difference between DNA and RNA?
DNA is a double-stranded genetic template, while RNA is single-stranded and transcribes genetic information to build proteins.
What is mitosis?
The division of somatic cells, producing two identical daughter cells.
What is meiosis?
A two-step division process that creates gametes (sperm and egg), reducing chromosome number by half.
What are alleles?
Different copies of the same gene located at the same position on paired chromosomes.
What is the difference between genotype and phenotype?
Genotype is the genetic composition, and phenotype is the observable traits.
What are Mendelian disorders?
Disorders caused by mutations in single genes, following autosomal dominant, autosomal recessive, or X-linked inheritance.
What are chromosomal disorders?
Disorders caused by structural or numerical chromosome abnormalities, often influenced by environmental factors.
What characterizes autosomal dominant inheritance?
A single mutated copy of the gene causes disease; affects males and females equally.
What are examples of autosomal dominant disorders?
Huntington disease, neurofibromatosis, von Willebrand disease, osteogenesis imperfecta.
What characterizes autosomal recessive inheritance?
Both copies of the gene must be mutated; males and females equally affected.
What are examples of autosomal recessive disorders?
Cystic fibrosis, sickle cell anemia, Wilson disease.
What characterizes X-linked inheritance?
The mutated gene is on the X chromosome; males are more frequently affected.
What is the most common chromosomal disorder?
Down syndrome (Trisomy 21).
What are examples of X-linked disorders?
X-linked recessive: Hemophilia; X-linked dominant: Vitamin-D resistant rickets.
What causes Down syndrome?
An extra copy of chromosome 21.
What are clinical features of Down syndrome?
Slanted eyes, short stature, heart abnormalities, variable intelligence, macroglossia, fissured tongue, hypodontia, crowding, gingival & periodontal disease.
What is the karyotype for Down syndrome?
47, XX, +21 (or 47, XY, +21).
What is the karyotype for Klinefelter syndrome?
47, XXY.
What are clinical features of Klinefelter syndrome?
Male phenotype, gynecomastia (breast development), hypogonadism, and sterility.
What is the karyotype for Turner syndrome?
45, X.
What are clinical features of Turner syndrome?
Female phenotype, webbed neck, hypogonadism.
What is the inheritance pattern of cyclic neutropenia?
Autosomal recessive.
What characterizes cyclic neutropenia?
Cyclic decrease in neutrophils (~every 3 weeks) lasting 2-3 days.
What are the oral manifestations of cyclic neutropenia?
Ulcerative gingivitis, periodontitis, oral ulcerations.
Why is optimal oral hygiene important in cyclic neutropenia?
Reduces the risk of oral infections during neutropenic periods.
What is the inheritance pattern of Papillon-Lefèvre syndrome?
Autosomal recessive.
What are the key features of Papillon-Lefèvre syndrome?
Severe periodontal destruction, premature tooth loss, hyperkeratosis of palms & soles.
What is gingival fibromatosis and what is the treatment?
A generalized, firm, fibrous gingival overgrowth.
Treatment is Surgical reduction of gingival tissue.
When does gingival fibromatosis typically present?
In childhood.
What type of disorder is Ehlers-Danlos syndrome?
A group of inherited connective tissue disorders.
What are the clinical features of Ehlers-Danlos syndrome?
Loose joints, hyperelastic skin, TMJ dysfunction, bruising, tooth abnormalities.
What is the Gorlin sign in Ehlers-Danlos syndrome?
Ability to touch the tip of the tongue to the nose.
What is the inheritance pattern of cherubism?
Autosomal dominant.
What are the key clinical features of cherubism?
Bilateral facial swelling (ages 1-4), mandible most affected, eye displacement with maxillary lesions.
What radiographic appearance is seen in cherubism?
Bilateral “soap bubble” multilocular radiolucencies.
What does a biopsy of cherubism show?
Giant cell lesions.
What is the inheritance pattern of Cleidocranial Dysplasia?
Autosomal dominant inheritance
What bones are primarily affected in cleidocranial dysplasia?
Skull and clavicles.
What is a key skeletal feature of cleidocranial dysplasia?
Underdeveloped or missing clavicles.
What dental abnormality is common in cleidocranial dysplasia?
Many unerupted supernumerary teeth (pseudoanodontia).
What is the inheritance pattern of Gardner syndrome?
Autosomal dominant inheritance
What is a major risk associated with Gardner syndrome?
Colon polyps with 100% malignant transformation after 30 years of age.
What jawbone abnormality is associated with Gardner syndrome?
Osteomas (benign bone overgrowths).
What preventive treatment is recommended for Gardner syndrome?
Prophylactic colectomy.
What is the inheritance pattern of Treacher Collins syndrome?
Autosomal dominant.
What are the key facial abnormalities in Treacher Collins syndrome?
Hypoplastic mandible, high-arched palate, dental abnormalities, lower eyelid cleft (coloboma).
What is the inheritance pattern of Gorlin Syndrome?
Autosomal dominant inheritance
What are the key features of Gorlin syndrome?
Hypertelorism (wide-set eyes), basal cell carcinomas, multiple odontogenic keratocysts, bifid ribs.
What is the treatment for Gorlin syndrome?
Surgical removal of basal cell carcinomas and jaw cysts.
What is the inheritance pattern of Osteogenesis Imperfecta?
Autosomal dominant inheritance
What is the primary defect in osteogenesis imperfecta?
Collagen defect leading to fragile bones and multiple fractures.
What oral manifestation is seen in osteogenesis imperfecta?
Dentinogenesis imperfecta-like condition (opalescent teeth).
Are primary or permanent teeth more affected in osteogenesis imperfecta?
Primary teeth (80%), permanent teeth (35%).
Which is more common: cleft lip alone or cleft lip with cleft palate?
Cleft lip with cleft palate is twice as common as cleft lip alone.
Are cleft lip and palate inherited?
They are multifactorial but can be part of inherited syndromes.
What is a complete cleft lip?
A cleft that extends to the nostril.
What is the treatment for cleft lip and cleft palate?
Surgical correction, sometimes combined with orthodontic procedures.
What is the inheritance pattern of hereditary hemorrhagic telangiectasia?
Autosomal dominant.
What are the oral signs of MEN2B?
Multiple mucosal neuromas on the lips and tongue.
What are key features of hereditary hemorrhagic telangiectasia?
Dilated blood vessels on skin and mucosa, especially the tongue, and frequent nosebleeds (epistaxis).
Why is this condition significant for dental hygiene procedures of hereditary hemorrhagic telangiectasia?
Oral lesions may bleed easily.
What is the inheritance pattern of MEN2B?
Autosomal dominant inheritance
What life-threatening condition is associated with MEN2B?
Medullary thyroid carcinoma.
What is a preventative treatment for MEN2B?
Preventative thyroidectomy.
What is the inheritance pattern of neurofibromatosis?
Autosomal dominant.
Where do neurofibromas commonly occur in the oral cavity?
Tongue, gingiva, intraosseous areas.
What is a potential risk associated with neurofibromas?
Some may become malignant.
What skin feature is common in neurofibromatosis?
Café au lait pigmentation.
What is the inheritance pattern of Peutz-Jeghers syndrome?
Autosomal dominant inheritance
What are the key oral signs of Peutz-Jeghers syndrome?
Multiple melanotic macules on skin and mucosa.
What gastrointestinal risk is associated with Peutz-Jeghers syndrome?
Polyposis with a high risk of developing cancer.
What is the inheritance pattern of white sponge nevus?
Autosomal dominant.
What are the oral manifestations of white sponge nevus?
White, corrugated, soft folded mucosa on bilateral buccal mucosa.
What does amelogenesis imperfecta affect?
The enamel of teeth, with no systemic defects.
What are the four types of amelogenesis imperfecta ?
Hypoplastic, hypocalcified, hypomaturation, hypoplastic-hypomaturation.
What are the clinical features of dentinogenesis imperfecta type II?
Bulbous crowns, opalescent brown to brown-blue teeth.
What is seen on a radiograph in dentinogenesis imperfecta type II?
No pulp chambers.
Which teeth are more affected in dentinogenesis imperfecta type II?
Primary teeth are more severely affected than permanent teeth.
What are the two types of dentin dysplasia?
Radicular and coronal.
What are key features of radicular dentin dysplasia?
Normal crowns, abnormal roots, lack of pulp chambers.
What are the three main features of ectodermal dysplasia?
Hypodontia (few teeth), hypotrichosis (sparse hair), hypohidrosis (reduced sweating).
What is the genetic pattern of ectodermal dysplasia?
Genetic heterogeneity (mostly X-linked, some autosomal recessive).
What are key features of coronal dentin dysplasia?
Translucent amber-colored primary teeth, thistle-shaped pulp chambers in permanent teeth.
What enzyme is decreased in hypophosphatasia?
Serum alkaline phosphatase.
What is a severe complication of ectodermal dysplasia?
Hyperthermia due to lack of sweat glands.
What are key oral manifestations in hypophosphatasia?
Spontaneous premature shedding of teeth due to defective cementum.
What are key skeletal features in hypophosphatasia?
Improper bone formation, rachitic-like changes, bowing of the legs, multiple fractures.
What is the genetic pattern of hypophosphatasia?
Autosomal recessive inheritance
