Aurora magazine

In Puerto Rico and the Dominican Republic, cystic fibrosis is linked to a genetic mutation almost impossible to find elsewhere. The discovery comes from a team of UC San Francisco and the Centro de Neumología Pediátrica of San Juan. Scientists have shown that most Dominican patients have none of the typical mutations in Europe.

The genetic causes of the disease are therefore other, much more rare elsewhere. Cystic fibrosis is a genetic disorder that afflicts 70,000 people worldwide. The diagnosis occurs in the first years of life, following abnormal accumulation of mucus in the lungs and in the digestive tract. At one time, children with the disease died very young.

The new treatments have improved life expectancy and today the average age is 40 years. Nevertheless, the drugs do not work on a large chunk of the sick, especially Latins. This raised several questions for doctors. At the Centro de Neumología Pediátrica in Puerto Rico, classic genetic tests are ineffective for 25% of patients with cystic fibrosis. The authors therefore hypothesized that the common genetic mutations in the Caucasian population are different from those of other ethnic groups.

The scientists analyzed the DNA of 21 Puerto Rican patients and 61 Dominicans, all of which were negative in the tests. Total genetic sequencing has revealed that the mutations linked to cystic fibrosis in these populations are different. Those present in 90% of Caucasian patients are present only in 33% of Puerto Rican patients and in 10% of Dominican ones. Conversely, mutations present in only 1% of Caucasian patients are widespread. This means that therapies will also have to be developed based on these mutations.

Source: eurekalert.org

In the past three decades, the twins have become a real cultural phenomenon. In fact, the country included the highest number of twins living in the world. The main cause of this boom was the use of fertility treatments, which began to spread in the 1980s. Today, the twins are back to decline.

What happened? In 1980, the rate of twin births was around 1.8%. It was then that fertility treatments became increasingly common. At that time, the treatments still included the implantation of more embryos per cycle. This increased the chances of having a twin birth, sometimes even tri-twin. As a result, the percentage of twins increased by up to 2% year on year. In 2014, it arrived at a rate of 33.9%, more than a third of the total parts. Between 2014 and 2018, we witnessed a new drop in twin births. In 2018, the United States had "only" 32.6% of twin births.

The decrease is particularly evident in more adult women: among mothers aged 30-34, the drop was 10%; for those over 35 years, by 23% and passes. Instead, it remained almost identical in women around the age of 20. According to the authors of the report, it is difficult to say with certainty what the causes of the decline are.

However, by concentrating in the most adult groups, it is likely to be linked to changes in assisted reproduction techniques. Today, in fact, it is rare for doctors to transfer more than one embryo at a time. Multiple pregnancies are less likely to succeed and are even more dangerous for future mothers.

Source: sciencealert.com

About 1 in 6 Canadian couples has fertility problems. Some of these seek the solution in in vitro fertilization, with mixed results. A study by the University of Montreal explained why some attempts fail, although there is no apparent reason.

The reason lies in a mechanism that reduces the chances of the embryo implanting and developing. Healthy cells have only one nucleus, containing DNA with all the genetic information. It happens that embryos obtained with IVF have cells with two nuclei instead of one.

The doctors call them "binucleate embryos" and, in many cases, still try to implant them in the patients' uterus. According to the study, this could lead to unintended consequences. Scientists have observed binuclear mouse embryos and it has emerged that having two nuclei can be harmful.

The presence of the double nucleus increases the chances that the embryo will develop a condition called aneuploidy. In such cases, the embryo has more or less chromosomes. Most often, it fails to develop and pregnancy ends spontaneously. When the implantation in the uterus takes place, aneuploidy causes diseases such as Down Syndrome. According to the authors, the study would give new guidelines for fertility clinics.

Selecting only embryos with cells from a nucleus would increase the chances of success, avoiding that couples should suffer unsuccessful and useless attempts.

Source: chumtl.qc.ca

A team of scientists from Scripps Research has created a genomic technique that facilitates the study of rare diseases. The technique serves in fact to trace the causes, comparing the activity of the maternal and paternal alleles. When levels fall out of the normal range, they insert the allele into the possible causes of the disease. This allows you to narrow the circle and facilitate analysis.

The researchers were looking for a way to identify rare genetic diseases, especially those with early appearance. Standard sequencing methods identify already known genetic mutations, which cause protein deficits. At least half of rare genetic diseases, however, have much more subtle causes. For example, traditional sequencing does not see mutations affecting regions of DNA but not genes.

This is a big problem, as these regions regulate the way genes work. When they do not work properly, the activities of the genes change accordingly and the diseases are manifested. Still, they are invisible mutations for traditional tests. At conception, we inherit a set of maternal alleles and a paternal set. In order for a genetic disease to manifest itself, it is almost always necessary that the anomaly is present in both alleles.

This does not apply to many rare genetic diseases, which also occur with only one anomalous allele. To identify them, the team analyzed the activities of all pairs of alleles. Couples with a strong gradient between one allele and the other are the probable causes of the disease. To test the technique, the researchers used it on patients suffering from rare muscular dystrophies. Thanks to the methodology, they identified all areas of DNA related to the disease. Now the goal is to use the technique on risky newborns, so as to intervene as soon as possible against the disease.

Source: scripps.edu