Cancer Syndromes Flashcards
What gene is associated with ataxia-teangiectasia?
ATM (recessive form)
What’s the prevalence of AT?
1:40,000-1:100,000 live births
When does AT typically present? Life expectancy?
infancy to childhood
roughly 20 years
What’s the less severe form of AT?
AT Variant (later onset and slower progression)
What biochemical testing is done to diagnose AT? Genetic analysis?
ATM protein levels
AFP levels
radiosensitivity
chromosome analysis
full-gene of both alleles for ATM variants
What are some of the main manifestations of AT?
CNS manifestations (early-onset cerebellar ataxia)
telangiectasias (oculocutaneous)
immunodeficiency
25-40% lifetime risk fo malignancies (hematologic and some solid)
ectodermal, respiratory, and endocrine manifestations
What percent of the population have one germline ATM variant?
0.5-1%
What cancers are associated with germline variants in ATM? Risks?
Breast (15-40%)
Pancreatic (5-10%)
Ovarian (<3%)
some evidence for prostate, colorectal, melanoma, and gastric
When would you test for ATM variants?
FHx or personal history of ovarian, breast, and/or pancreatic cancer
Where is ATM mainly expressed?
lymph nodes, spleen, and appendix, found in many other tissues
What is the ATM gene involved in? product?
coordinating cellular signaling pathways (double-stranded DNA repair, oxidative stress, cell-cycle checkpoint)
produces a protein kinase
What types of variants are most common in ATM? Which one confers most breast cancer risk?
missense or nonsense, splicing, small deletions
c.7271T>G
What types of screening is performed for AT? treatment?
screening:
- blood testing, avoiding radiography, abdominal US in adulthood, breast MRI for females starting at age 25
treatment:
avoid radiotherapy
avoid chemotherapy and other harsh pharmaceuticals (reduced dosage)
Do those with ATM variants require risk-reducing surgery?
no they do not
What type of gene is PALB2?
partner and localizer with BRCA2 and aids in tumor suppression
also works with BRCA2 to repair damaged DNA
What happens to DNA in the absence of PALB2?
increased chromosomal instability (more breaks)
What penetrance is associated with PALB2?
moderate-high
What types of diagnostic testing can be performed for PALB2?
known familial mutation
full sequence analysis
del/dup analysis
What is the lifetime brca risk in women with a PALB2 variant? ovca? pancreatic?
40-60%
slightly increased ovca
5-10% pancreatic risk in M and W
How can we manage risk in someone with a PALB2 variant?
mamm. and MRI every 12mo starting @ 30 and/or prophylactic mastectomy
ocva: manage based on FHx, salpingo-oophorectomy after 50y
Panc: beginning at 50y (or 10y younger than age of dx) annual MRI or endoscopic US
How do we treat cancer in those with PALB2 variants?
PARP inhibitors
surgical considerations in brca
Homozygous for PALB2 = ______. Leads to?
fanconi anemia subtype
physical differences and DD, malignancy (leukemia and lymphoma in childhood)
PALB2 can resemble what other genes ina. FHx?
BRCA1/2
POLD1/POLE code for: _________. Most pathogenic variants are:
DNA polymerases
missense and LoF
Variants in POLD1/POLE impact proofreading and are associated with what types of conditions?
polymerase proofreading associated polyposis (PPAP)
Are there any extracolonic cancers associated with POLD1/POLE?
brain, endometrial, breast, stomach, pancreas, and skin
When should we test for POLD1/POLE?
if there are at least 10 adenomas in a FHx
What types of management would someone with a POLD1/POLE variant receive?
colonoscopy started btwn 14-20y and repeated as indicated by polyp burden
- 25-30y (NCCN)
Upper GI endoscopy should start btwn 25-30y
What type of gene is STK11? Aka?
tumor suppressor gene
LKB1
What syndrome is associated with STK11? prevelance? how many experience symptoms <10y?
Peutz-Jehgers syndrome
1/25,000-1/280,000
1/3