BA can also occur in a systemic form (BA-splenic malformation), in conjunction with heterotaxy, congenital heart disease, and polysplenia amongst other midline defects.[12] To date, there are very few published studies describing the association between MMP-7 levels in neonates and infants with cholestasis and CHD, though some studies in older children and adults have looked at the association of MMP levels and pulmonary hypertension.[13]. The gene discussed is MMP7; the disease is congenital heart disease.