All three genes are located on the long (i.e. "p") arm of human chromosome 4 (at positions 4q31.3, 4q31.3, and 4q32.1, respectively) and may contain mutations that are the cause of congenital dysfibrinogenemia. The heximer is assembled as a protein in the endoplasmic reticulum of hepatocytes and then transferred to the Golgi where Polysaccharides (i.e. complex sugars) and sialic acid are added by respective glycosylation and sialylation enzyme pathways thereby converting the heximer to a functional fibrinogen glycoprotein. The final circulating glycoprotein (notated as (AαBβγ)2, (αβγ)2, Aα2Bβ2γ2, or α2β2γ2) is arranged as a long flexible rod with nodules at both ends termed D domains and central nodule termed the E domain.[11][12]