SNP Shot: Genomic Insights

Hereditary spherocytosis (HS) is a disorder that affects red blood cells, often leading to anemia (a shortage of red blood cells), jaundice (yellowing of the skin and eyes), and splenomegaly (an enlarged spleen). While newborns with HS frequently experience severe anemia, it usually improves after the first year. Splenomegaly can develop at any point from childhood to adulthood. Gallstones, hard deposits in the gallbladder, affect approximately half of individuals with HS, typically developing between late childhood and mid-adulthood.

HS is classified into four types based on the severity of symptoms: mild, moderate, moderate/severe, and severe. The mild form affects 20-30% of individuals with HS, the moderate form affects 60-70%, the moderate/severe form affects around 10%, and the severe form affects 3-5%.

Individuals with mild HS may have very mild anemia or no symptoms at all. The moderate form typically presents with anemia, jaundice, and splenomegaly, and many individuals develop gallstones, often during childhood. The moderate/severe form exhibits all the features of the moderate form but with more pronounced anemia. The severe form is characterized by life-threatening anemia requiring regular blood transfusions, severe splenomegaly, jaundice, and a high likelihood of developing gallstones. Some individuals with severe HS may also experience short stature, delayed sexual development, and skeletal abnormalities.

Inheritance:

Hereditary spherocytosis is most commonly inherited in an autosomal dominant manner (approximately 75% of cases). This means that only one copy of a mutated gene is needed to cause the condition. An affected individual may inherit the mutation from a parent who also has HS. In other cases, the mutation occurs spontaneously in a person with no family history of the condition. HS can also be inherited in an autosomal recessive manner, which requires two copies of the mutated gene. In this case, both parents carry one copy of the mutated gene, but they generally do not show signs or symptoms of the disorder.