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Genetic Syndromes 2


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What type of inheritance is Achondroplasia?
(Dwarfism): Autosomal Dominant (caused by de novo mutations in germline mosaicism or advanced paternal age)
What is mutated gene in Achondroplasia
FGFR3 gene mutation: Transmembrane Tyrosine Kinase Receptor
What has the phenotype Prenatal onset, Rhizomelic short stature, megalenchephaly, and Spinal cord compression?
Phenotype of Achondroplasia (dwarfism)
What 2 genes are affected in hereditary Breast and Ovarian Cancer?
BRCA 1 and 2
What is the inheritance pattern for the BRCA 1 and 2 genes?
Autosomal dominant with incomplete penetrance. (Tumor suppression Gene, Two-Hit mutation)
What is the phenotype of Mylogenous Leukemia?
Leukemia: Leukocytosis, splenomegaly, fatigue, Blast Crisis fatal;
What is the translocated chromosome in Chronic Myelogenous Leukemia?
Philadelphia Chromosome
What is a Philadelphia Chromosome?
Translocation between chromosome 9 and 22 affecting the ABL and BCR gene regions. Causes Chronic Myelogenous Leukemia
What is the inheritance pattern for Chronic Myelogenous Leukemia?
Somatic mutation and can not be inherited
What is the inheritance pattern for Cystic Fibrosis?
Autosomal Recessive
What gene is affected by Cystic Fibrosis?
CFTR gene on chromosome 7q31 which codes for a protein that is a regulated CL- channel located in the apical membrane of the epithelial cells.
What is the most common mutation allele for the CF gene?
del F508
What is included in the phenotype for cystic fibrosis?
Pulmonary disease, pancreatic insufficiency, sweat chloride, and neonatal onset.
What is the inheritance for Duchenne Muscular Dystrophy?
X-linked recessive inheritance (de novo mutation)
What is the genetic mutation for duchenne muscular dystrophy?
DMD Mutation (deletions and duplications) which normally encodes for the protein dystrophin.
What is a positive Gower sign and what syndrome is it associated with?
This is a specific getting up routine in which the child uses the upper extremity to help himself. Suggests severe impairment of lower extremity muscles. Associated with Duchenne's Muscular dystrophy.
What type of gene is contributes to Familial Adenomatous Polyposis (FAP)?
A Tumor Suppression gene mutation is associated with this cancer. Specifically the APC tumor suppressor gene.
What is the inheritance pattern for familial adenomatous polyposis (FAP)?
autosomal dominant (Two-hit mutation)
What is the phenotype for familial adenomatous polyposis?
an enormous amount of polyps in the colon and colorectacl cancer.
What type of inheritance does Familial hypercholestrolemia have?
autosomal dominant, with environmental modifiers
Where is the mutation for familial hypercholesterolism?
Mutation in the LDL Receptor mutation causes this disorder of cholesterol and lipid metabolism.
What is the phenotype for familial hypercholesterolism?
hypercholesterolemia, atherosclerosis, Xanthomas, Arcus cornea
What is the phenotype for Fragile X syndrome?
mental retardation, dysmorphic facies, male macroorchidism (abnormally large testes)
How is Fragile X Syndrome inherited?
X-Linked recessive
What is the mutation associated with Fragile X Syndrome?
FMR1 Mutation which is a triplet repeat expansion with hypermethylation leading to loss of expression.
What is the inheritance pattern for hemophilia?
X-Linked recessive disorder
What is the mutation associated with hemophilia A and B?
F8C or F9 mutation (factor 8 or 9) [del, ins, point mutations, inv]
What is the phenotype for hemophilia?
Bleeding diathesis, hemarthroses, hematomas
What is a curative therapy for Chronic myelogenous Leukemia?
allogeneic bone marrow transplantation
What type of cancer gene contributes to chronic myelogenous leukemia?
oncogene. Specifically the BCR-ABL (fusion protein) oncogene
What type of gene contributes to hereditary nonpolyposis colon cancer and which gene specifically? (of the three types of genes contributing to cancer)
This is a DNA mismatch repair gene cancer. Specifically MSH2 and MSL1 among others.
What type of inheritance pattern does hereditary nonpolyposis colon cancer have?
Autosomal dominant with incomplete penetrance
What phenotypes are associated with Hereditary Nonpolyposis Colon Cancer?
Has variable expressivity. Colorectal cancer with increased risks of endometrial, stomach, biliary tract and other cancers.
What is the inheritance pattern for Huntington Disease?
Autosomal Dominant
What is the phenotype for Huntington disease?
The phenotype for this neurodegenerative disease includes motor, cognitive, psychiatric abnormalities
What mutation is Huntington's Disease caused by?
the HD mutation is a triplet repeat expansion.
How is Marfan Syndrome inherited?
Autosomal dominant
What mutation is associated with the connective tissue disorder, Marfan Syndrome?
Mutation in Fibrilli-1 gene
What is the phenotype for Marfan Syndrome
Multisystem: skeletal (scoliosis, disproportionately tall, joint laxity); ocular (extopia lentis, flat corneas) cardiovascular (mitral valve prolapse, aortic problems); pulmonary (spontaneous pneumo-thorax and apical blebs); skin (striae atrophicae, recurrent herniae); dural (lumbosacral extasia)...phenotypes consistent within families but severities vary.
What is the major cause of premature death for Marfan Syndrome?
heart failure
What is the genetic cause of Miller Dieker Syndrome and how is this diagnosed?
hemizygous deletion on Chromosome 17p13 (LIS 1 gene) and diagnosed via FISH
What is the phenotype for Miller-Dieker Syndrome?
Lissencephaly (smooth-brain); facial dysmorphism, global mental deficiency, early death, seizures
How is Myclonic Epilepsy with Ragged-red Fibers inherited?
Matrilineal, mitochondrial DNA
What is the phenotype associated with Myclonic Epilepsy with Ragged-red Fibers?
dementia, myopathy, myclonic seizures, ataxia, deafness.
How is retinoblastoma inherited?
Autosomal Dominant
What type of gene contributes to retinoblastoma?
tumor suppressor gene (Rb mutation); follows two hit mechanism
What typically differentiates sporadic from familial retinoblastoma?
Familial- Bilateral, multiple tumors, early onset (w/in first year), in germline
Sporadic- Unilateral, single tumor, later onset
What is the phenotype for Sex Reversal?
Sterility, reduced secondary sexual features, unambiguous genitalia
What is the genetic basis for Sex Reversal?
Chromosomal or Y-Linked inheritance (caused by an SRY on an X chromosome) mutation, deletion or translocation.
How can Sex Reveral be diagnosed?
How is Tay-Sachs Disease inherited and what population is it associated with?
Autosomal Recessive in Ashkenazic Jewish population
What is the mutation causing Tay-Sachs disease?
HEXA mutation affecting ganglioside metabolism
What is the phenotype for Tay-Sachs disease?
Neurodegeneration, retinal Cherry-redspot, psychosis
How is thrombophilia inherited?
Autosomal Dominant
What genes are mutated in thrombophilia
There is a gain of function for the FV gene and a loss of function of the PROC gene
What is the phenotype for Thrombophilia?
deep vein thrombosis (blood clot)
What event leads to Turner Syndrome?
X monosomy and variants. Due to nondisjunction
What is the phenotype for Turner Syndrome?
short stature, ovarian dysgenesis, sexual immaturity, congenital lymphedema, infertility, web neck in adults, coarctation of aorta
What treatment is involved with Turner Syndrome?
parent counseling, growth hormone, estrogen and progesterone
What other disorder is associated with the same chromosomal mutation as Prader-Willi Syndrome and how do these two differ genetically?
Angelman Syndrome- The absence of maternally derived 15q11-q13 (by maternal del of 15q11-q13, or paternal uniparent disomy of chromosome 15s)

Prader-Willi- the absence of paternally derived 15q11-q13. (by paternal del, or maternal uniparental disomy of chromosome 15s)
What is the phenotype for Prader Willi Syndrome
infantile feeding difficulties, hyperphagia, obesity, hypotonia, cognitive impairment, sterility, dysmorphism
What is the major cause of morbidity for the Prader-Willi syndrome?
Obesity including cardiopulmonary disease and type 2 diabetes mellitus

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