Although how elevated TGF-β levels are responsible for the specific pathology seen with the disease is not proven, an inflammatory reaction releasing proteases that slowly degrade the elastic fibers and other components of the extracellular matrix is known to occur. The importance of the TGF-β pathway was confirmed with the discovery of the similar Loeys–Dietz syndrome involving the TGFβR2 gene on chromosome 3, a receptor protein of TGF-β. Marfan syndrome has often been confused with Loeys–Dietz syndrome, because of the considerable clinical overlap between the two pathologies. Marfanoid–progeroid–lipodystrophy syndrome
Marfanoid–progeroid–lipodystrophy syndrome (MPL), also referred to as Marfan lipodystrophy syndrome (MFLS), is a variant of MFS in which Marfan symptoms are accompanied by features usually associated with neonatal progeroid syndrome (also referred to as Wiedemann–Rautenstrauch syndrome) in which the levels of white adipose tissue are reduced. Since 2010, evidence has been accumulating that MPL is caused by mutations near the 3-terminus of the FBN1 gene. It has been shown that these people are also deficient in asprosin, a gluco-regulatory protein hormone which is the C-terminal cleavage product of profibrillin. The levels of asprosin seen in these people were lower than expected for a heterozygous genotype, consistent with a dominant negative effect. Diagnosis
Diagnostic criteria of MFS were agreed upon internationally in 1996. However, Marfan syndrome is often difficult to diagnose in children, as they typically do not show symptoms until reaching pubescence.
Fetal-maternal haemorrhage is the loss of fetal blood cells into the maternal circulation. It takes place in normal pregnancies as well as when there are obstetric or trauma related complications to pregnancy. Normally the maternal circulation and the fetal circulation are kept from direct contact with each other, with gas and nutrient exchange taking place across a membrane in the placenta made of two layers, the syncytiotrophoblast and the cytotrophoblast. Fetal-maternal haemorrhage occurs when this membrane ceases to function as a barrier and fetal cells may come in contact with and enter the maternal vessels in the decidua/endometrium. Description
Normal pregnancy
It is estimated that less than 1ml of fetal blood is lost to the maternal circulation during normal labour in around 96% of normal deliveries. The loss of this small amount of blood may however be a sensitising event and stimulate antibody production to the foetal red blood cells, an example of which is Rhesus disease of the newborn. Abnormal pregnancy
Causes of increased foetal-maternal haemorrhage are seen as a result of trauma, placental abruption or may be spontaneous with no cause found. Up to 30ml of foetal-maternal transfusion may take place with no significant signs or symptoms seen in either mother or foetus. Loss in excess of this may result in significant morbidity and mortality to the fetus. Fetal-maternal haemorrhage is one cause of intrauterine death (IUD). Diagnosis
The Kleihauer–Betke test is a blood test used to measure the amount of foetal hemoglobin transferred from a foetus to its mothers bloodstream.