Aurora magazine

It is now only a matter of years to transfer one embryo at a time during in vitro fertilization. This significantly reduces the risk of multiple pregnancies. Nevertheless, it is not avoided in its entirety. It sometimes happens that a single embryo gives rise to a twin or even plurigemellar pregnancy. How is it possible? A study led by Dr. Keiji Kuroda, published on Human Reproduction, speaks of this.

The rate of twin pregnancies after a single implant is 1.6%. Approximately 1.36% of gestations are linked to a process called zygotic meiosis. The study examines 937,848 cycles of in vitro fertilization with implantation of a single embryo. The researchers looked for all the factors that could be related to the phenomenon, both in the mother and in the process. From what has emerged, the "assisted hatching" technique could be one of the possible causes of embryo division.

The meiosis of the zygote occurs between the second and the sixth day after fertilization of the oocyte. In this phase, the zygote is divided into many cells called blastomere, which will form the embryo. It happens that the zygote breaks in two and that each part forms an independent zygote, from which an embryo will develop. Sometimes, the zygote breaks even into three. The embryos all have the same genetic heritage, they are therefore monozygotic or identical twins.

It can be difficult to understand which multiple pregnancies are the result of meiosis of the zygotic and which of other factors. In some cases, a sexual act during the IVF cycle can translate into a double pregnancy. One caused by in vitro fertilization and the other natural. The only sure way is to use ultrasound to see if there are more gestational bags and how many fetuses are. If the fetuses are more than the gestational bags, then the multiple pregnancy is caused by the meiosis of the zygotic.

Source: medicalxpress.com

In Switzerland, all newborns receive prenatal screening for phenylketonuclear syndrome or PKU. It is a genetic disease that affects the metabolism, caused by a malfunction of the enzyme phenylalanine hydroxylase. The team of Professor Gerald Schwank used CRISPR / Cas9 for the first time to correct mutated genes. For the time being the procedure has been applied only to animal models and has been completely successful.

PKU causes the progressive accumulation of phenylalanine in tissues, damaging neurons and causing mental retardation. Researchers used genetic editing to transfer the correct genetic code into liver cells. Thanks to the procedure, they modified about 60% of the abnormal copies of the gene and stimulated the production of the missing enzyme first. As a result, phenylalanine dropped to normal levels and most of the symptoms disappeared.

The procedure used is slightly different from the traditional one and is also much more efficient. The attempts made with the traditional version of CRISPR have indeed failed. The procedures had been able to correct only low percentages of cells. As a result, the effects on the guinea pigs had been very mild.

For the study in question, the scientists used adeno-associated viruses to carry the correct DNA. They injected them into the blood of guinea pigs, in order to infect the liver cells and introduce the new genes. This same method could also be useful in other metabolic diseases, even if it is still to be explored. According to Professor Gerald Schwank, the possible risks are reduced. Before moving on to human experimentation, it will still be necessary to switch from other animal models.

Source: ethz.ch/

Phenylketonuclear syndrome or phenylketonuria is a genetic disease that affects metabolism. The sufferer shows an abnormality in the gene that codes for the enzyme phenylalanine-hydroxylase. As a result, the body can not convert the essential amino acid phenylalanine into tyrosine, a precursor of dopamine. Phenylalanine accumulates in the blood and tissues, causing deficiency of serotonin and dopamine. If not addressed in time, the phenylketonuclear syndrome causes severe mental retardation.

The disease is caused by mutations that affect the PAH gene and is transmitted in an autosomal recessive manner. Both parents must be healthy carriers of the disease and the child must inherit the abnormal gene from both. Benign hyperphenylalaninemia is a less severe form of the disease, in which a minimum level of enzyme is maintained.

The diagnosis of phenylketonuria starts from the Guthrie test or another similar test. It is done on newborns and requires only a drop of blood. It allows a quick and precise diagnosis, so as to allow immediate action with the necessary treatments. If there were already cases in the family, prenatal diagnosis can be made. However, for genetic analysis it is necessary to know the mutations involved in the specific case.

If detected immediately, the phenylchetonuric syndrome can be kept under control with a strict diet. Those who suffer must avoid proteins, so as to limit the intake of phenylalanine. This leaves very few foods on the list and makes it difficult to follow the diet, with serious consequences on the neuropsychological level.

Source: telethon.it

Unlike many cells in the rest of our body, the brain cells have variable DNA. It changes cell in cells, due to somatic changes. The phenomenon could explain diseases like Alzheimer's or autism, but remains largely unexplained. Scientists at the Sanford Burnham Prebys Medical Discovery Institute (SBP) have developed a new approach that allows us to identify the magnitude and location of these changes.

Thanks to the new technique, scientists have detected thousands of previously unknown variations. Many of these appear in the prenatal stage, particularly in the most important stages of brain development. It is therefore likely that they are an integral part of the process, even if its purpose is not yet known.

The study clarifies critical points on the number of changes in brain cell DNA. The merit is a technique that integrates cell sequencing. Because this destroys the cells examined in the process, the scientists recombined the DNA using immune cells. In this way they have created cell models with alterations, making it easier to detect them during analysis.

The technique was developed by a team formed by Illumina scientists. Applied to single cells during neurogenesis, it has allowed to find thousands of new genetic variants. Most of these were characterized by deleted DNA areas, while duplications were rarer. The variants were randomly distributed in the genome, but developed almost all in the neurogenesis period.

Source: medicalxpress.com