The protein encoded by this gene is a member of the
somatotropin/prolactin family of hormones and plays an important
role in growth control. The gene is located at the growth hormone
locus on chromosome 17 along with four other related genes in the
same transcriptional orientation; an arrangement which is thought
to have evolved by a series of gene duplications. Although the five
genes share a remarkably high degree of sequence identity, they are
expressed selectively in different tissues. Alternative splicing
generates additional isoforms of each of the five growth hormones,
leading to further diversity and potential for specialization. This
particular family member is expressed mainly in the placenta and
utilizes multiple transcription initiation sites. Expression of the
identical mature proteins for chorionic somatomammotropin hormones
1 and 2 is upregulated during development, although the ratio of 1
to 2 increases by term. Mutations in this gene result in placental
lactogen deficiency and Silver-Russell syndrome. [provided by
RefSeq].
