Hereditary spherocytosis

The ideal duration of antibiotic prophylaxis for children is not clear. Recommendations for daily prophylaxis differ among different authorities.^[1] Guidelines in the United States suggest relatively limited courses of post-splenectomy prophylaxis (up to five years of age and for at least one year after splenectomy), whereas British guidelines recommend lifelong penicillin prophylaxis in high-risk individuals (defined as those less than 16 or more than 50 years of age, and those with an inadequate response to pneumococcal vaccination).^[1]

The American Academy of Pediatrics Committee on Infectious Diseases published a policy statement in 2000 which included the following information:^[2]

• Antibiotic prophylaxis is recommended for all children with sickle cell disease (SCD) and functional or anatomic asplenia, regardless of whether they have received pneumococcal immunizations.
• Although the efficacy of penicillin prophylaxis in children with functional or anatomic asplenia other than SCD has not been studied, it is reasonable to use prophylaxis in the same regimen.
• Antibiotic prophylaxis should be begun before 2 months of age or as soon as SCD or asplenia occurs or is otherwise recognized or suggested by screening procedures.
• Oral administration of penicillin V potassium is recommended at a dosage of 125 mg twice a day until 3 years of age and at a dosage of 250 mg twice a day after 3 years of age.
• Children who have not experienced invasive pneumococcal infection and have received recommended pneumococcal immunizations may discontinue penicillin prophylaxis after 5 years of age.^[2]

It has also been stated that individuals in whom prophylaxis is being discontinued should have well-established, regular medical care, and understand the warning symptoms and signs, as well as the management, of possible post-splenectomy sepsis. Individuals with highly compromised immune systems, and survivors of pneumococcal post-splenectomy sepsis, are reasonable candidates for prophylaxis until age 18, or even for life.^[1]

Individuals looking for specific medical advice for themselves or family members should speak with their health care provider.

About 75% of cases of hereditary spherocytosis are inherited in an autosomal dominant manner.^[3] This means that having a change (mutation) in only one copy of the responsible gene in each cell is enough to cause features of the condition. In some cases, an affected person inherits the mutated gene from an affected parent. In other cases, the mutation occurs for the first time in a person with no family history of the condition. This is called a de novo mutation. When a person with a mutation that causes an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit that mutation.

Less commonly, hereditary spherocytosis is inherited in an autosomal recessive manner.^[3] This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:

• 25% (1 in 4) chance to be affected
• 50% (1 in 2) chance to be an unaffected carrier like each parent
• 25% chance to be unaffected and not be a carrier

In some of the cases that result from new mutations in people with no family history of the condition, the inheritance pattern may be unclear.^[3]

The offspring of an individual affected with an autosomal dominant (AD) form of hereditary spherocytosis has a 50% (1 in 2) risk to inherit the same mutation in the disease-causing gene. If a child of an affected parent with AD hereditary spherocytosis does not inherit the mutation, that child will not pass the mutation on to his/her children because it is not present in his/her genes.

The offspring of an individual with an autosomal recessive (AR) form of hereditary spherocytosis will definitely be a carrier of the condition. A carrier of an AR condition is generally only at risk to have an affected child if his/her partner is also a carrier for the condition, having a mutation in the same disease-causing gene. When 2 carriers of an AR condition have children, each child has a 25% (1 in 4) risk to be affected. If a carrier has a child with an individual who is not a carrier, that child will not be affected.