Conceptually interpreted amino acid sequences of the pre-S gene of the mother and two daughters. The sequences were compared with a reference hepatitis B virus sequence (genotype C, serotype adw, Genbank accession number ABR22121, at the top row). Amino acid residues identical to the reference sequence were represented by short lines. Deletions are represented by slashes. PS1, the initiation codon of the large surface protein; PS2, the initiation codon of the middle surface protein.