Aberrant splicing contributes to severe α-spectrin-linked congenital hemolytic anemia

Area of Science:

• Genetics
• Hematology
• Molecular Biology

Background:

• Recessive hereditary spherocytosis (rHS) and hereditary pyropoikilocytosis (HPP) are severe hemolytic anemias with largely unknown causes.
• Erythrocyte membrane α-spectrin (SPTA1) is crucial for red blood cell stability.

Purpose of the Study:

• To investigate the genetic basis of rHS and HPP in patients lacking identified SPTA1 mutations.
• To elucidate the molecular mechanism underlying spectrin deficiency in a subset of these disorders.

Main Methods:

• Whole exome and whole genome sequencing of affected families.
• In vitro minigene and in vivo splicing analyses.
• mRNA stability studies.

Main Results:

• Identified a novel disease mechanism in one-third of mutation-negative SPTA1 alleles.
• A rare intron 30 variant creates a strong alternative branch point, leading to aberrant mRNA splicing.
• Aberrant splicing produces an elongated transcript with a premature termination codon, triggering nonsense-mediated decay and spectrin deficiency.

Conclusions:

• A unique mechanism of genetic disease involving altered mRNA splicing contributes to rHS and HPP etiology.
• This finding facilitates diagnosis and treatment of severe anemia.
• Identifies a new potential target for therapeutic intervention.