[Molecular genetic basis for para-Bombay phenotypes in two cases]

Area of Science:

• Molecular Genetics
• Blood Group Serology
• Human Genetics

Background:

• The para-Bombay phenotype is a rare blood group variant that can cause transfusion complications.
• Understanding its molecular genetic basis is crucial for accurate blood typing and transfusion practices.

Observation:

• Two individuals with the para-Bombay phenotype were identified through serological testing.
• Genetic analysis focused on the alpha (1, 2) fucosyltransferase genes (FUT1 and FUT2).

Findings:

• Direct sequencing and TOPO TA cloning revealed compound heterozygous mutations in the FUT1 gene of both probands.
• The identified mutations were an AG deletion (c.547-552delAG) causing a frameshift and premature stop codon, and a C-to-T substitution (c.658C>T) resulting in an amino acid change (p.Arg220Cys).
• These mutations, designated h1h3, were confirmed to be on separate homologous chromosomes.

Implications:

• The compound heterozygous FUT1 mutations (h1h3) are proposed as the genetic cause of the para-Bombay phenotype in these individuals.
• This finding contributes to the understanding of blood group genetics and the molecular basis of rare phenotypes.
• Accurate genetic identification of para-Bombay phenotype can prevent transfusion reactions and improve patient care.