Understanding patterns of inheritance is one of the most important foundations in medical genetics. Among them, autosomal dominant inheritance is frequently tested in undergraduate exams, NEET PG, INI CET, and other competitive medical entrance examinations.
In this article, we will simplify autosomal dominant inheritance and discuss some high-yield conditions associated with it using an easy-to-remember mnemonic.
To watch the complete explanation by Dr. Anand, you can view here:
What is Autosomal Dominant Inheritance?
In autosomal dominant (AD) inheritance:
- Only one mutated copy of the gene is sufficient to cause the disease.
- Both males and females are equally affected.
- The condition often appears in every generation (vertical transmission).
- An affected individual has a 50% chance of passing the condition to offspring.
- Unaffected individuals usually do not transmit the disease.
Because of its strong transmission pattern, autosomal dominant disorders are commonly asked in viva exams and MCQs.
The Mnemonic: MLT–MAT
A simple mnemonic to remember important autosomal dominant conditions is:
MLT–MAT
Let’s break it down in a logical and easy way.
1. M – Marfan Syndrome
Marfan syndrome is one of the classic examples of autosomal dominant inheritance.
Key Features:
- Caused by mutation in the FBN1 gene (fibrillin-1)
- Tall stature with long limbs (arachnodactyly)
- Lens dislocation (usually upward)
- Aortic root dilation → risk of aneurysm
It is a favorite exam topic because it integrates genetics, cardiology, and ophthalmology.
2. A – Achondroplasia
Achondroplasia is the most common cause of disproportionate dwarfism.
Key Features:
- Mutation in the FGFR3 gene
- Short limbs with normal trunk
- Large head with frontal bossing
- Normal intelligence
A very important exam point:
Although inherited in an autosomal dominant manner, many cases result from new mutations, especially with increased paternal age.
3. T – Cri-du-chat Syndrome
Cri-du-chat syndrome is associated with a deletion of the short arm of chromosome 5 (5p deletion).
Key Features:
- High-pitched, cat-like cry in infancy
- Microcephaly
- Intellectual disability
- Distinct facial features
Though chromosomal deletion disorders are sometimes discussed separately, it is often included in autosomal dominant-type inheritance discussions in exam mnemonics.
The “Opposite of M is W” Trick
To strengthen recall, use a logical alphabetical association:
If M stands for Marfan, think of the opposite side of the alphabet visually as W.
This helps you remember two more important autosomal dominant conditions:
4. W – Williams Syndrome
Williams syndrome is caused by a microdeletion on chromosome 7.
Key Features:
- “Elfin” facial appearance
- Intellectual disability
- Friendly, outgoing personality
- Supravalvular aortic stenosis
- Hypercalcemia in infancy
It is commonly tested due to its distinctive personality traits and cardiovascular association.
5. W – Von Willebrand Disease
Von Willebrand disease (most common type) follows autosomal dominant inheritance.
Key Features:
- Deficiency or dysfunction of von Willebrand factor
- Mucosal bleeding
- Epistaxis
- Prolonged bleeding time
- Normal platelet count
There are the most common inherited bleeding disorders, which making it a highly important exam topic.
Summary Table for Quick Revision
| Condition | Key Feature | Inheritance |
| Marfan Syndrome | Tall stature, aortic aneurysm | Autosomal Dominant |
| Achondroplasia | Short limbs, FGFR3 mutation | Autosomal Dominant |
| Cri-du-chat | Cat-like cry, 5p deletion | Autosomal Dominant (commonly remembered as AD) |
| Williams Syndrome | Elfin face, supravalvular AS | Autosomal Dominant |
| Von Willebrand Disease | Mucosal bleeding | Autosomal Dominant (common type) |
Why Mnemonics Matter in Medical Preparation
Overall medical education involves that remembering the vast amounts of information. Mnemonics like MLT–MAT help:
- It helps to improve the rapid recall during MCQs
- Strengthen the overall viva performance
- Will reduce the last-minute exam stress
- Make revision faster and more efficient
However, memorization should always be combined with the conceptual clarity. While understanding the genetic basis and the overall clinical presentation which make sure about the long-term retention.
A Final Thought for Medical Students
Success in the medicine does not come from occasional bursts of motivation. It comes from consistent daily effort. The key is to enjoy your learning routine rather than seeing it as a burden.
You know what, knowledge is truly a one-time investment that gives lifelong returns, in exams, in practice, and in patient care and in many more things.
So revise smartly for your exam, stay consistent, and keep building your concepts step by step.
Happy learning.
