ABSTRACT:
In this article, we will discuss about the inheritance patterns of genetic diseases. Several inheritance patterns such as autosomal recessive and dominant, X-linked recessive and dominant describe disease inheritance. Some traits are dominant in males and females and some are recessive. For instance: Hemophilia is dominant in males and recessive in females. Similarly, milk production is dominant in females and recessive in males. We will also describe the sex-linked and sex-influenced traits.
INTRODUCTION OF INHERITANCE PATTERNS OF GENETIC DISEASES:
Genetic diseases can be inherited from an affected individual to their offspring. The passing down of genetic disorders follows specific patterns that can be traced through generations. Understanding these inheritance patterns is crucial for genetic counselors and healthcare professionals to provide accurate diagnoses, manage risks, and offer appropriate treatments. In this article, we will explore the different inheritance patterns of genetic diseases along with real-life examples and references to support our understanding. https://www.ncbi.nlm.nih.gov/books/NBK115561
TYPES OF INHERITANCE PATTERNS OF GENETIC DISEASES:
AUTOSOMAL DOMINANT INHERITANCE:
In autosomal dominant inheritance, a single copy of an abnormal gene from one affected parent is sufficient to cause the disease in an offspring. The affected gene is typically located on one of the 22 pairs of autosomes, rather than the sex chromosomes. Example: Huntington’s disease is a classic example of autosomal dominant inheritance. The abnormal HTT gene is responsible for this degenerative neurological disorder.
2. AUTOSOMAL RECESSIVE INHERITANCE:
For autosomal recessive inheritance, both copies of a gene (one from each parent) must be abnormal for the disease to manifest. Carriers, individuals with one copy of the abnormal gene, typically do not show any signs of the disease but can pass it on to their children. Example: Cystic fibrosis is an autosomal recessive disorder caused by mutations in the CFTR gene, affecting the production of mucus and enzymes.
3. X-LINKED INHERITANCE:
X-linked inheritance mainly affects males, with the abnormal gene located on the X chromosome. Females can be carriers of the disease if they inherit one copy of the abnormal gene but generally do not exhibit symptoms. Example: Duchenne muscular dystrophy is an X-linked recessive disorder caused due to mutations in the dystrophin gene and it leads to progressive muscle weakening and loss.
4. Y-LINKED INHERITANCE:
Y chromosomes passed from father to son and Y-linked inheritance is exclusive to male. Inheritance of genetic disease associated with Y-chromosomes is from father to son. Example: Y-linked infertility, such as azoospermia, is due to mutations in genes present on the Y chromosome that are essential for spermatogenesis.
CONCLUSION:
Understanding the inheritance patterns of genetic diseases is vital for accurate diagnoses, effective management, and counseling for affected individuals, families, and healthcare professionals. Autosomal dominant, autosomal recessive, X-linked, and Y-linked patterns are the main classification systems. By considering the inheritance patterns and appropriate genetic testing, healthcare professionals can provide comprehensive care and offer the best guidance to patients and their families.
REFERENCES:
The Huntington’s Disease Collaborative Research Group. (1993). A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington’s disease chromosomes. Cell, 72(6), 971-983.
Riordan, J. R., et al. (1989). Identification of the cystic fibrosis gene: cloning and characterization of complementary DNA. Science, 245(4922), 1066-1073.
Monaco, A. P. et al. (1986). An explanation for the phenotypic differences between patients bearing partial deletions of the DMD locus. Genomics, 1(4), 359-366.
Y-linked inheritance is exclusive to males, as Y chromosomes are only passed from father to son. Any genetic diseases associated with the Y chromosome are inherited from the father.
Abbadi, N., et al. Additional case of female monozygotic twins discordant for the clinical manifestations of Duchenne muscular dystrophy due to opposite X-chromosome inactivation. American Journal of Medical Genetics 52, 198–206 (1994).
Antonarakis, S. E., & Beckmann, J. S. Mendelian disorders deserve more attention. Nature Reviews Genetics 7, 277–282 (2006) doi10.1038/nrg1826. https://www.nature.com/scitable/content/Mendelian-disorders-deserve-more-attention-20648
