Genetic Syndromes Flashcards
1
Q
human somatic cells contain
A
- 23 pairs of chromosomes
- - 22 autosomes, 1 pair sex (X,Y)
2
Q
codons
A
- triplet sequence of nucleotides
- determines a specific amino acid that is inserted into a protein
3
Q
gene
A
- length of DNA that codes for a specific protein
- Locus– specific location of a gene on a chromosome
4
Q
polymorphism-
A
altered gene sequence that does not cause disease
5
Q
mutation
A
- altered gene sequence that causes a disease
- may be naturally occurring, spontaneous, or secondary to radiation/chemicals
- larger genes are more likely to undergo mutations
- mutation rates may be increased with advanced maternal or paternal age
6
Q
single point mutation
A
- base pair substitution that may lead to amino acid change
7
Q
deletion or insertion-
A
may result in missing or extra AA. potential changes all down stream AA
8
Q
general clinical phenotypes seen in chromosomal abnormalities
A
- developmental delay
- cognitive impairment
- growth delay
- short stature
- congenital malformations
9
Q
Trisomy 21-
A
Dows syndrom
10
Q
Trisomy 18
A
- Edward’s syndrome
- 2nd most common trisomy observed in term babies
- 100+ associated typical malformations: cardiovascular, GI, urogenital, skeletal, hand deformity, overlapping fingers
- mean survival is 2 weeks
11
Q
Cri-du-chat syndrome (cat’s cry)
A
- 5 p
- 85% due to spont deletion
- cat like cry in infancy, low birth wt, hypotonia, feeding difficulties, failure to thrive, microcephaly, small jaw, wide mouth wide sent eyes with downward sloping palpebral fissures, epicanthal folds, strabismus, low set ears, broad nasal ridge
- clumsiness and hyperactivity with repetitive body movements
- chronic sleep disturbances
- moderate to severe intellectual disabilities50% can communicate by ag e10
- self injurious behavior, hypersensitivity to sound
12
Q
Chromosomal microdeltions such as
Prader-willi syndrome and angelman syndrome
A
- genetic defect in both syndromes is the deletion on the long arm of chromosome 15
- if inherited from the mother the child presents with AS
- if inherited from the father child develops PWS
13
Q
Prader-willi syndrome
A
- characterized by diminished featl activity, respiratory and feeding difficulties in infancy , hypotonia, and decreased pigmentation of skin and eyes
- short stature, small hands and feet, small genitalia, hypogonadism
- excessive eating- must be externally controlled to decreased risk of obesity
- intelligence rage from normal to low/mod disability. behavior problems-tantrums, stubbornness, manipulative, autism ADHD, OCD
- motor milestones at twice typical
14
Q
Angelman syndrome
A
- severe learning difficulties, ataxia with jerky movments, puppet-like gait, seizure disorder with characteristic EEG, sleep disorder
- frequent and sometimes inappropriate laughter
- subtle dysmorphic facial features: wide, smiling mouth, maxillary hypoplasia, prominent chin, drop-set, often pale-blue eyes
-expressive seech is rare, ASL recommended
15
Q
sex- linked disorders
X-linked recessive
A
- majority are recessive, may skip a generation with females as cariers
- duchenne MD- most common recessive x-linked dirsorder
- hemophilia A. defective or lack of clotting factor VII
