Inherited diseases Flashcards
What type of inheritance pattern does cystic fibrosis follow?
Autosomal recessive.
What gene is mutated in cystic fibrosis, and what protein does it encode?
The CFTR gene on chromosome 7 encodes the CF transmembrane conductance regulator protein, which is involved in ion transport.
What are the main clinical features of cystic fibrosis?
Accumulation of mucus, recurrent infections (e.g., Pseudomonas aeruginosa), and excessive inflammation in the lungs.
Why is DNA testing performed for cystic fibrosis?
To confirm diagnosis, determine prognosis, perform prenatal testing, identify at-risk family members, and for newborn screening.
What is the inheritance pattern of hereditary hemochromatosis?
Autosomal recessive.
What gene is associated with hereditary hemochromatosis?
The HFE gene on chromosome 6.
What is the primary characteristic of hereditary hemochromatosis?
Deposition of iron in tissues, leading to organ damage.
What tests are performed after confirming HFE gene mutations?
Transferrin saturation, serum ferritin, and DNA testing of at-risk family members.
What is the inheritance pattern of CPS I deficiency?
Autosomal recessive.
What is the role of CPS I in the urea cycle?
It catalyzes the first step of the urea cycle, converting ammonia into carbamoyl phosphate.
What is the consequence of CPS I deficiency?
Accumulation of ammonia, which can lead to coma and death.
How is DNA testing performed for CPS I deficiency?
Indirect testing using linkage studies to track the disease gene through a family.
What is the inheritance pattern of achondroplasia?
Autosomal dominant.
What gene is mutated in achondroplasia?
The FGFR3 gene on chromosome 4, which encodes the fibroblast growth factor receptor 3 protein.
Why is prenatal testing performed for achondroplasia?
To confirm the diagnosis of achondroplasia in the fetus.
What is the inheritance pattern of Huntington disease?
Autosomal dominant.
What is the molecular basis of Huntington disease?
An increase in the number of CAG repeats in the HD gene on chromosome 4.
How is DNA testing performed for Huntington disease?
PCR is used to determine the exact number of CAG repeats.
What causes Down syndrome?
An extra copy of chromosome 21 (trisomy 21).
What are the clinical features of Down syndrome?
Distinct facial appearance, intellectual disability, developmental delays, and possible thyroid or heart disease.
How is Down syndrome diagnosed prenatally?
Through amniotic fluid or chorionic villus sampling.
What causes Patau syndrome?
An extra copy of chromosome 13 due to nondisjunction.
What are the clinical features of Patau syndrome?
Severe intellectual disability, heart defects, brain or spinal cord abnormalities, and cleft lip/palate.
What causes Edwards syndrome?
An extra copy of chromosome 18.
