Cystic fibrosis is an example of?

JODHPUR AIIMS SNO-2018

Pathology & Genetics

Easy

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

Cystic fibrosis (CF) is an inherited disorder that follows an autosomal recessive transmission pattern.
This means an individual must inherit two copies of the mutated CFTR gene, one from each parent, to develop the disease.
The gene is located on chromosome 7, which is an autosome (non-sex chromosome), hence the term 'autosomal'.
Parents of an affected child are typically heterozygous carriers, meaning they have one mutated allele and one normal allele, and are usually asymptomatic.

Option B: X-linked dominant disorders are caused by mutations on the X chromosome and require only one mutated allele to cause the disease. This pattern involves different transmission risks from father to daughter versus father to son, which is not characteristic of CF.
Option C: Autosomal dominant disorders require only one copy of the mutated gene to be inherited for the disease to be expressed. In CF, inheriting one mutated gene makes a person a carrier, not affected by the disease.
Option D: X-linked recessive disorders are caused by mutations on the X chromosome and primarily affect males. Females are typically carriers. CF affects males and females equally, which rules out an X-linked pattern.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Genetic Inheritance Patterns as background academic context rather than a clinical decision trigger.
Nurses play a vital role in educating families about the inheritance of cystic fibrosis, explaining the 25% risk with each pregnancy if both parents are carriers.
Genetic counseling is a key intervention. Nurses can identify at-risk families and facilitate referrals for testing and counseling to help them make informed reproductive decisions.
A nurse's understanding of CF's genetic basis informs comprehensive care, including screening newborns, managing multi-system symptoms (respiratory, digestive), and providing psychosocial support.

How to Approach the Question

First, identify the core concept of the question, which is the mode of genetic inheritance for a specific disease (Cystic Fibrosis).
This is a factual recall question. Access your knowledge base about common genetic disorders.
Recall that Cystic Fibrosis is the most common lethal genetic disease in Caucasian populations and is known for its characteristic inheritance pattern.
Evaluate each option: 'Autosomal' means the gene is on a non-sex chromosome, and 'recessive' means two copies of the gene are needed. This matches the known genetics of CF.
Eliminate the other options. 'X-linked' patterns show different rates in males and females, which is not true for CF. 'Dominant' patterns would mean carriers are affected, which is also not true for CF.
Select 'Autosomal recessive disorder' as the correct answer based on this systematic evaluation.

Concept Tested & Keywords

Q_lp6OhY9kTjXKivc1kvsn

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed pp. 153-155, 472-474

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 417-419