In many of the male patients, macroorchidism can be observed after puberty. Storage at -80 C allowed them to be kept for longer. Results Fetal blood has special characteristics that complicate FMRP diagnostics. These are difficult to differentiate morphologically from fetal lymphocytes, apart from being slightly smaller and having a different chromatin structure. As they do not express detectable amounts of FMRP, their inclusion in the cell pool would lead to the false impression of a reduced degree of FMRP expression in fetal lymphocytes.
Erythroblasts appear mainly during the early fetal period.
Their number decreases with fetal development. Accurate diagnostics using fetal blood therefore require both the detection of the protein in the lymphocytes and the differentiation of these from the erythroblasts in the tested pool of cells. To achieve this aim, we combined two distinct antibody incubation procedures for each sample. One procedure had two steps and the other three. This reacts with a Fuchsin chromogen substrate to form a red precipitate, allowing the visualisation of the FMRP in the lymphocyte cytoplasm.