Figure 4.

The chromosomal organization of SPFTPA locus consists of two functional genes the SFTPA2 encoding SP-A2 and the SFTPA1 encoding surfactant protein A (SP-A1) as well as a pseudogene, the SFTPA3 as shown in (A). The location of the centromere (C) and the telomere (T) are depicted. The transcriptional orientation is shown by a bent arrow. The two functional genes have opposite transcriptional orientation. The coding variants for each gene are shown below the relevant gene and the size of the circle denotes the frequency of each in the general population with the 1A⁰ and 6A² being the most frequently observed variants. (B) depicts hetero-oligomers and homo-oligomers.