Common Chromosomal Disorders Flashcards
Inheritance of an extra copy of one chromosome results in a condition called _____.
trisomy
Most commonly, trisomies occur when one pair of chromosomes fails to separate properly during meiosis, a problem termed _____.
nondisjunction
The most common trisomy that results in a live birth is trisomy _____ (#).
21
The most common trisomies are _____ (#), _____ (#), and _____ (#), and contain relatively few gene alleles.
21, 18, 13
Trisomy of chromosomes containing more alleles is more likely to be embryo _____.
lethal
The presence of extra sex chromosomes, especially the _____ chromosome, is relatively common.
X
What type of congenital heart defect is most common in trisomy 21?
cardiac cushion defects
Name the trisomy:
- small, strawberry-shaped head with receding chin, small jaw, and elongated occiput
18
Name the trisomy:
- microcephaly, micrognathia, cleft lip
13
Name the trisomy:
- epicanthal folds with upslanting palpebral fissures
- short neck with limited motion and extra skin folds
- cardiac cushion defects
21
Name the trisomy:
- atrial-septal defects, ventricular-septal defects, coarctation of the aorta
- omphalocele
- esophageal atresia
18
Name the trisomy:
- dextrocardia, atrial-septal defects, ventricular-septal defects, PDA
- polydactyly, syndactyly
- umbilical and inguinal hernias
13
Name the trisomy:
- holoproencephaly (fusion of brain hemispheres)
- low-set ears
- deafness, vision problems
- seizures
- apnea
13
Name the trisomy:
- Brushfield spots (speckling) on iris
- shorter stature than siblings
- hypothyroidism
- increased risk for leukemia
21
_____ with trisomy 21 are sterile.
Males
Females with trisomy 21 have a _____% chance of producing a zygote with trisomy 21.
50
Of those that are not stillborn, over _____% of trisomy 18 births die within the first year.
90
Of those that are not stillborn, over _____% o trisomy 13 births die within the first year.
90
List the 4 syndromes of extra X chromosomes:
trisomy X
tetrasomy X
pentasomy X
Klinefeltier syndrom
While _____ X is more common with normal phenotype (but usually are taller than average with slight delay in language development and a higher incidence of shyness and lack of self-confidence), _____ X and ______ X are much rarer are are consistently associated with phenotypic abnormalities.
- trisomy
- tetrasomy
- pentasomy
Females with _____ X are usually tall and have a greater reduction in IQ (35-70), smaller heads, and minor changes in facial features with increased incidence in skeletal abnormalities and unstable behavior.
tetrasomy
Fewer than 40 females who have _____ X have been reported and have greatly reduced IQ, short stature, cleft palate, hypotonia, coarse facial features, microcephaly, hypertelorism (large distance between the eyes), and congenital heart defects.
pentasomy
Men can have an extra X chromosome, resulting in a 47,XXY karyotype, also known as _____ _____.
Klinefelter syndrome
The cause of _____ _____ is both maternal and paternal nondisjunction and is associated with both maternal and paternal aging with fetal survival about _____%.
- Klinefelter syndrome
2. 97
Features of _____ _____ include: declining testosterone with increased FSH by young adult age, small testes and penis, gynecomastia (50% of cases), azospermia (lack of sperm production), oligospermia, decreased libido, osteoporosis, SLE, thyroid disease, diabetes, breast CA, non-Hodgkin lymphoma, and germ cell tumors.
Klinefelter syndrome
Features of having an extra _____ chromosome include taller than average, more severe teenage acne, slower motor and language development, learning disabilities, more easily distracted, hyperactive, more easily frustrated, impulsivity, disorganized and aggressive behavior.
Y
Inheriting only one chromosome of a pair is a condition called _____.
monosomy
The only common incidence of monosomy is _____ syndrome in which a female is missing one of the X chromosomes and has a karyotype of 45,X, along with very few cases of monosomy 21 reported.
Turner
_____% of Turner syndrome individuals do not survive the first trimester.
99
Name the syndrome:
short stature, wide chest, disproportionally large hands and feet, congenital dislocated hip, scoliosis, kyphosis, osteoporosis, pedal edema hygroma, high/arched narrow palate, widely spaced eyes, poor dentition, wide mandible with small chin, low posterior hairline.
Turner
What are possible cardiovascular problems associated with Turner syndrome?
- Coarctation of the aorta
- bicuspid aortic valve
- aortic dissection
- hypertension
- coronary artery disease
- long Q-T syndrome
- partial anomalous pulmonary connection
What are possible endocrine problems associated with Turner syndrome?
- hypothyroidism
2. Diabetes mellitus types 1 and 2
What are possible renal problems associated with Turner syndrome?
- collecting-system malformations
- horseshoe-shaped kidney
- malrotation of one or both kidneys
What are possible eye and vision problems associated with Turner syndrome?
- epicanthal folds (skinfold of upper eyelid)
- drooping eyelids
- uptilted palpebral fissures (opening between the upper and lower eyelids)
- red-green color blindness
- strabismus (misalignment of the eyes)
- hyperopia (farsightedness)
What are possible ear and hearing problems associated with Turner syndrome?
- malformed ears
- unusual relationship between position of eustachian tube and middle ear
- excessively high incidence of otitis media
- conductive hearing loss
- progressive sensorineural hearing loss (adults)
- cholesteatoma formation (abnormal skin growth in the middle ear behind the ear drum)
What are possible secondary sexual features (without hormone supplementation) associated with Turner syndrome?
- absent or delayed menses
- poor breast development
- infertility
- ovarian dysgenesis with loss of ova and fibrotic changes
- small, underdeveloped uterus
_____ is the inheritance of an extra copy of each chromosome, resulting in a person who has 69 chromosomes per cell instead of 46, usually lethal, with none reaching first birthday.
Triploidy
Unlike trisomy and monosomy, most partial chromosome duplications and deletions are _____ events that result from chromosomal breakage and structural rearrangement, usually during gametogenesis, not related to paternal age, with usually no reproductive capability.
random
WAGR syndrome is a _____ syndrome standing for:
- deletion
2. Wilm’s tumor (nephroblastoma), Aniridia (absence of the iris), Genitourinary malformations, and Retardation
While the other features of WAGR syndrome are always present, the risk for Wilm’s tumor is _____%.
40
More rarely occurring, the inherited type of _____ is missing the RB gene on at least one chromosome 13 whose role is a cancer suppressor gene in preventing transcription factors from enhancing cell division.
retinoblastoma
Name the deletion syndrome:
microcephaly, cleft lip and palate, hypertelorism (widely spaced eyes), epicanthal folds, low-set earts with few folds, small chin, a variety of heart defects, decreased cognition.
Cri Du Chat
Name the deletion syndrome:
normal appearance at birth, feeding difficulties, developmental delay, slow gain of head circumference, unsteady or clumsy gait with jerky motions, frequent smiles and laughs regardless of circumstances, easily excited personality and hand waving or flapping motions, impaired speech, seizures, occipital groove, protruding tongue, large mouth with widely spaced teeth, drooling, strabismus, and lighter pigmentation than parents and siblings
Angelman
Name the deletion syndrome:
normal appearance at birth, narrow face, lighter pigmentation than family members, hypotonia, poor sucking reflex, failure to thrive, short stature, small hands and feet, developmental delays with reduced cognition, small gonads, insatiable appetite, behavioral problems, delayed puberty, infertility
Prader-Willi
True or false:
Angelman and Prader-Willi syndromes are both a result of the deletion of chromosome 15 from q11 to q13.
True
_____ syndrome is maternally derived and _____ syndrome is paternally derived from the deletion of chromosome 15 from q11 to q13.
- Angelman
2. Prader-Willi
Genomic _____ is an epigenetic event in which a gene (or gene allele) is inactivated by means other than mutation, so the DNA sequence of the gene remains normal but its expression is inhibited.
imprinting
When a gene or genes have been iprinted during gametogenesis, the effect of an imprinted gene allele from one parent means that only the nonimprinted gene allele from the other parent is _____.
expressed
For the most part, when the nonimprinted gene allele is _____, its sole expression is not a problem.
normal
In _____ _____ (UPD), both chromosomes of a pair come from just one parent.
uniparental disomy
When a child has uniparental disomy (UPD) of chromosome 15 with both chromosomes being derived from the father, and there is no deletion of material on either chromosome, _____ syndrome results.
Angelman
When a child has uniparental disomy (UPD) of chromosome 15 with both chromosomes being derived from the mother, and there is no deletion of material on either chromosome, _____ results.
Prader-Willi
_____ is a condition in which two (or more) different karyotypes are consistently present in one individual.
Mosaicism
_____ can be tissue-specific, meaning that some tissues can express a mixture of normal and abnormal karyotypes, and other tissues may express all or nearly all of just one type.
Mosaicism
