X-Linked Severe Combined Immunodeficiency (X-SCID)
Description
X-Linked Severe Combined Immunodeficiency (X-SCID), also known as "bubble boy disease", is a rare genetic disorder that affects the immune system. This disorder makes individuals highly susceptible to infections, as their bodies cannot fight off bacteria, viruses, or fungi effectively. This blog delves into the intricacies of X-SCID, covering its causes, symptoms, diagnosis, management, and the remarkable progress being made in treatment.
Genes Involved
X-SCID is primarily caused by mutations in genes involved in the development and function of T cells and natural killer (NK) cells. These genes include:
- IL2RG: This gene encodes the common gamma chain, a crucial component of several cytokine receptors involved in immune cell development.
- JAK3: This gene encodes a protein kinase that plays a role in signaling pathways essential for immune cell function.
- XIAP: This gene encodes a protein that inhibits apoptosis, or programmed cell death, in immune cells.
Recognizing the Signs and Symptoms
Infants with X-SCID often exhibit recurring infections, particularly of the respiratory system, skin, and digestive tract. These infections can be severe and life-threatening. Other signs may include failure to thrive, chronic diarrhea, and persistent fungal infections.
Causes
X-SCID is inherited in an X-linked recessive pattern. This means that the gene mutation responsible for the disorder is located on the X chromosome, and females carry two copies of the X chromosome while males carry one X and one Y chromosome. Females usually carry one normal copy of the gene, protecting them from the disease. However, they can be carriers and pass the mutation to their sons.
Affected males inherit the mutated gene from their mothers and develop the disorder.
Inheritance/recurrence risk
If one parent has the X-SCID gene, the chance of their child inheriting it is 50%. If both parents carry the gene, there is a 25% chance of their child having the disease. If a male has X-SCID, his daughters will be carriers, and his sons will not be affected.
