38 Questions
What is the function of fibrillin in the extracellular matrix?
It forms a sheath around elastin
Which of the following is a common feature of Marfan syndrome?
Tall and slender build
What is the main concern if the aorta is affected in Marfan syndrome?
Life-threatening condition
What is the result of valve deformities in Marfan syndrome?
Aortic regurgitation or mitral valve prolapse
What is the name of the gene that causes Pseudoachondroplasia?
COMP
What is the function of the COMP protein?
It is essential for the normal development of cartilage
Where is the COMP protein normally found?
In the spaces between cartilage-forming cells
What is the result of cartilage not converting to bone?
Cartilage is present in the nose and external ears
What is a characteristic of Classic DM1?
Muscle weakness and wasting, myotonia, cataract, and cardiac conduction abnormalities
What is a common symptom of myotonic dystrophy type 2?
Prolonged muscle contractions and inability to relax certain muscles
What is the name of the protein associated with the CNBP gene?
CCHC-type zinc finger nucleic acid binding protein
What is the phenomenon where the signs and symptoms of a genetic condition become more severe and appear at an earlier age as the disorder is passed from one generation to the next?
Anticipation
Which of the following genetic disorders results from mutations in the fibrillin-1 (FBN1) gene on chromosome 15?
Marfan syndrome
What is a less common symptom of myotonic dystrophy type 2?
Clouding of the lens in the eyes
What is the main difference between myotonic dystrophy type 1 and type 2?
Type 1 is more severe and shortens lifespan, while type 2 is milder
What is the number of different mutations described in the fibrillin-1 (FBN1) gene?
Over 1500
What is the cytogenetic location of the Gaucher disease type 1 gene?
1q22
What is the most common type of Gaucher disease?
Type 1
What is the mode of inheritance of Gaucher disease type 1?
Autosomal-recessive
What is the result of the deficiency of acid β-glucosidase in Gaucher disease type 1?
Accumulation of glucocerebroside within lysosomes
What is a common complication of Gaucher disease type 1?
B-cell lymphoma
What is the function of beta-glucocerebrosidase?
To break down glucocerebroside into glucose and ceramide
What percentage of de novo mutations in NF1 are paternal in origin?
80%
What is the primary function of neurofibromin?
To act as a tumor suppressor
Who is credited with first describing the symptomatic red spot on the retina of the eye in 1881?
Waren Tay
What is the estimated number of mutations identified in the NF1 gene?
More than 500
What is the characteristic feature of NF1 clinical manifestations?
Extreme clinical variability
Which ethnic group has a similar carrier frequency of Tay-Sachs disease as Ashkenazi Jews, but with a different mutation?
French Canadians of Quebec ancestry
What is the protein produced by the NF2 gene?
Merlin (Schwannomin)
What is the current medical treatment for Tay-Sachs disease?
Supportive care to ease symptoms or extend life
What is the product of the three-gene system that encodes the α and β subunits of the enzyme?
Catalytically active Hex A
What is the typical location of tumors in NF2?
Both ears (acoustic neuromas)
What is the characteristic skin feature of NF1?
More than six cafe au lait spots
What is the mutation that leads to Tay-Sachs disease in Ashkenazi Jews?
Four-base insertion (TATC) in the Hex A gene
What is the consequence of a mutation in the HEXB gene?
Sandhoff disease
What is the estimated prevalence of NF2 compared to NF1?
NF2 is less common than NF1
What is the result of the four-base insertion (TATC) in the Hex A gene?
No detectable hex A protein is made
What is the approximate incidence of Tay-Sachs disease in Ashkenazi Jews?
1 in 3600
Study Notes
Myotonic Dystrophy
- Characterized by muscle weakness and wasting, myotonia, cataract, and often cardiac conduction abnormalities in classic DM1
- Adults with DM1 may become physically disabled and have a shortened life span
- Congenital DM1 is characterized by hypotonia and severe generalized muscle weakness
- Myotonic dystrophy type 2 is characterized by progressive muscle wasting and weakness, with symptoms typically beginning in a person's twenties
- Symptoms of myotonic dystrophy type 2 include prolonged muscle contractions, slurred speech, temporary locking of the jaw, muscle pain and weakness, and cardiac conduction defects
Anticipation
- The phenomenon of anticipation occurs when the signs and symptoms of a genetic condition become more severe and appear at an earlier age as the disorder is passed from one generation to the next
- Anticipation is most often seen with certain genetic disorders of the nervous system, such as Huntington disease, myotonic dystrophy, and fragile X syndrome
Marfan Syndrome
- Autosomal dominant disorder caused by mutations in the fibrillin-1 (FBN1) gene on chromosome 15
- Characterized by tall and slender build, disproportionately long arms, legs, and fingers, and a breastbone that protrudes outward or dips inward
- Symptoms include heart murmurs, high, arched palate, and crowded teeth
- Complications include widening and tearing of the aorta, valve deformities, and mitral valve prolapse
Pseudoachondroplasia
- Autosomal dominant disorder caused by mutations in the COMP gene
- Characterized by short-limbed dwarfism, with cartilage and bone abnormalities
- De novo mutations are paternal in origin, with no evidence of anticipation
Neurofibromatosis
- NF1 is a multisystem disorder with neurological, musculoskeletal, ophthalmological, and skin abnormalities, and a predisposition to neoplasia
- Caused by mutations in the NF1 gene, which regulates cell growth and differentiation
- Symptoms include cafe au lait spots, skin and bone abnormalities, and an increased risk of tumors
Tay-Sachs Disease
- Autosomal recessive disorder caused by mutations in the HEXA gene, leading to a deficiency of the enzyme hex A
- Characterized by the accumulation of glucocerebroside in nerve cells, leading to progressive nerve damage and death
- Symptoms include muscle weakness, seizures, and loss of motor skills
- No current medical treatment exists, with patients receiving supportive care to ease symptoms or extend life
Gaucher Disease
- Autosomal recessive disorder caused by mutations in the GBA1 gene, leading to a deficiency of the enzyme beta-glucocerebrosidase
- Characterized by the accumulation of glucocerebroside in macrophages, leading to variable expressivity of the disease
- Symptoms include hepatosplenomegaly, anemia, bone disease, coagulation abnormalities, and lung disease
This quiz covers Gaucher disease type 1, the most common lysosomal storage disease, its genetic causes, and its varying symptoms. Learn about the autosomal-recessive inheritance, prevalence in Ashkenazi heritage, and the role of the GBA1 gene.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
