Gene
SFTPA1 is located in the long arm of chromosome 10, close to SFTPA2. The SFTPA1 gene is 4505 base pairs in length, and 94% similar to SFTPA2. The structure of SFTPA1 consists of four coding exons (I-IV), and several 5'UTR untranslated exons (A, B, B’, C, C’,D, D’). The expression of SFTPA1 is regulated by cellular factors including proteins, small RNAs (microRNAs), glucocorticoids, etc. Its expression is also regulated by epigenetic and environmental factors.
Differences in the SFTPA1 gene sequence at the coding region determine SP-A genetic variants or haplotypes among individuals. More than 30 variants have been identified and characterized for SFTPA1 (and SFTPA2) in the population. SFTPA1 variants result from nucleotide changes in the codons of amino acids 19, 50, 62, 133, and 219. Two of these do not modify the SP-A1 protein sequence (amino acids 62 and 133), whereas the rest result in amino acid substitutions (amino acid 19, 50, 133, and 219). Four SP-A1 variants (6A, 6A2, 6A3, 6A4) are in higher frequency in the general population. The most frequently found variant is 6A2.
Read more about this topic: Pulmonary Surfactant-associated Protein A1