PATH 230: Test Quizzes with 100% Correct
Solutions
Down syndrome
Autosomal aneuploidy (Trisomy 21) causing intellectual disability, low nasal bridge, epicanthal
folds, protruding tongue, low-set ears, poor muscle tone
Down syndrome risk factor
Maternal age >35 increases risk
Turner syndrome karyotype
45,X Only one X chromosome, no homologous X or Y
Turner syndrome characteristics
Underdeveloped ovaries, short stature, webbed neck, edema, underdeveloped breasts, wide
nipples, high number of aborted fetuses
Fragile X syndrome mutation
Fragile site on long arm of X chromosome; expansion at FMR1 gene → abnormal epigenetic
inactivation
Fragile X inheritance pattern
X-linked dominant, can be inherited from either parent; more severe in males (only one X)
Fragile sites
Chromosomal regions with breaks/gaps when cells are cultured
, Klinefelter syndrome karyotype
Typically 47,XXY, may be XXXY; extra X increases severity
Klinefelter characteristics
Male appearance, gynecomastia, small testes, sparse body hair, long limbs
Klinefelter inheritance
Not inherited; random nondisjunction event
Cystic fibrosis mutation type
Frameshift mutation in CFTR gene → defective chloride transport → thick mucus
Cystic fibrosis inheritance
Autosomal recessive, parents are carriers; 25% recurrence risk
Duchenne inheritance
X-linked recessive; passed from mother → affected sons
Duchenne pathology
Mutation in dystrophin gene → progressive skeletal & cardiac muscle weakness
Prader-Willi syndrome cause
Genomic imprinting; loss of paternal genes
Prader-Willi features
Hyperphagia, obesity, hypotonia, short stature, cognitive impairment
Solutions
Down syndrome
Autosomal aneuploidy (Trisomy 21) causing intellectual disability, low nasal bridge, epicanthal
folds, protruding tongue, low-set ears, poor muscle tone
Down syndrome risk factor
Maternal age >35 increases risk
Turner syndrome karyotype
45,X Only one X chromosome, no homologous X or Y
Turner syndrome characteristics
Underdeveloped ovaries, short stature, webbed neck, edema, underdeveloped breasts, wide
nipples, high number of aborted fetuses
Fragile X syndrome mutation
Fragile site on long arm of X chromosome; expansion at FMR1 gene → abnormal epigenetic
inactivation
Fragile X inheritance pattern
X-linked dominant, can be inherited from either parent; more severe in males (only one X)
Fragile sites
Chromosomal regions with breaks/gaps when cells are cultured
, Klinefelter syndrome karyotype
Typically 47,XXY, may be XXXY; extra X increases severity
Klinefelter characteristics
Male appearance, gynecomastia, small testes, sparse body hair, long limbs
Klinefelter inheritance
Not inherited; random nondisjunction event
Cystic fibrosis mutation type
Frameshift mutation in CFTR gene → defective chloride transport → thick mucus
Cystic fibrosis inheritance
Autosomal recessive, parents are carriers; 25% recurrence risk
Duchenne inheritance
X-linked recessive; passed from mother → affected sons
Duchenne pathology
Mutation in dystrophin gene → progressive skeletal & cardiac muscle weakness
Prader-Willi syndrome cause
Genomic imprinting; loss of paternal genes
Prader-Willi features
Hyperphagia, obesity, hypotonia, short stature, cognitive impairment
