Mendelian Disorders: Inheritance, Types and Examples

Описание: Mendelian disorders are genetic disorders caused by mutation in a single gene and are inherited according to Mendel’s laws of inheritance. These disorders show predictable inheritance patterns such as autosomal dominant, autosomal recessive, and sex-linked (X-linked) inheritance. Since only one gene is involved, they are also called monogenic disorders.
Causes
Mutation or alteration in the DNA sequence of a gene
The mutation may be inherited from parents or occur spontaneously
Types of Mendelian Disorders
Autosomal Dominant Disorders
Only one mutant allele is sufficient to express the disorder
Affected individual has at least one affected parent
Examples:
Huntington’s disease
Achondroplasia
Polydactyly
Autosomal Recessive Disorders
Disorder is expressed only when both alleles are mutant
Parents are usually carriers
Examples:
Sickle cell anaemia
Phenylketonuria
Thalassemia
Sex-linked (X-linked) Disorders
Caused by mutation in genes present on the X chromosome
More common in males as they have only one X chromosome
Examples:
Haemophilia
Colour blindness
Duchenne muscular dystrophy
Characteristics of Mendelian Disorders
Follow Mendelian inheritance ratios
Usually show clear inheritance patterns in pedigrees
Do not depend on environmental factors for inheritance
Can be predicted using Punnett square analysis
Importance
Help in understanding human genetics and inheritance
Useful in genetic counselling
Aid in early diagnosis and management of genetic diseases
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