SNP Shot: Genomic Insights

Bare lymphocyte syndrome type II (BLS II) is a genetic immune disorder classified as a combined immunodeficiency (CID). Individuals with BLS II have extremely weak immune systems, leaving them highly vulnerable to bacteria, viruses, and fungi. This results in recurring and chronic infections that can be severe or fatal. These infections are frequently caused by opportunistic pathogens that typically don't harm individuals with healthy immune systems.

BLS II is generally diagnosed within the first year of a baby's life. Most affected infants experience ongoing infections in their lungs, digestive system, and urinary tract. These infections interfere with nutrient absorption (malabsorption) and hinder normal growth. Ultimately, these persistent infections can lead to organ failure. Without medical intervention, individuals with BLS II often don't survive beyond early childhood.

The underlying cause of BLS II is the absence of major histocompatibility complex (MHC) class II proteins on the surface of infection-fighting white blood cells (lymphocytes). This lack of MHC class II proteins is what gives the condition its name. BLS II is the most prevalent and well-understood of a group of similar disorders and is commonly known simply as bare lymphocyte syndrome (BLS).

Inheritance:

BLS II follows an autosomal recessive inheritance pattern. This means that a person must inherit two mutated copies of the responsible gene, one from each parent, to develop the condition. The parents, each carrying only one copy of the mutated gene, are usually unaffected carriers of the disorder.