The human body is an incredibly complex machine; the mere fact of knowing the names of all the bones, muscles, nerves, veins, arteries, fluids, genes, cells and other components takes years of study, let alone knowing their functions. And like in every machine with too many pieces, each one can fail individually, causing problems in the performance of the other components, sometimes in ways that at first thought do not make sense. Just like a helicopter that loses a nut, causing its blades to lose control and crash into the ground, in our body apparently slight and inconsequential changes can also take place, which in time can give rise to dangerous or even deadly pathological conditions.


To say that there are a lot of diseases would be kind of a big understatement. Some are quite common, such as an infection by a virus that causes flu, or the accidental consumption of bacteria that produces diarrhea. But, and this is where I wanted to get at before unnecessarily lengthening the introduction, there are some rare conditions that affect parts of the body that you did not even know existed, in ways you thought impossible. Luckily, here I am: the mechanic who explains to you what function had the nut that fell, and how that affected the rotating shaft of the blades causing the collision, only switching the oil stains on the clothes for blood, iodine, and coffee stains. Especially coffee.


I admit that I do not exactly have a lot of experience in terms of rare and unusual diseases (few do, though. They are rare and unusual), but I make up for it with access to the internet and infinite curiosity, as well as knowledge about anatomy, physiology and physiopathology that I have acquired throughout my studies. Because of this, I have come up with the idea of sharing my own research on the strangest diseases I can find, and share them with you, my dear steemians, in a series of posts, describing them in detail but in a simple way and with my characteristic style. Now, seeing that I already have 3 paragraphs without saying anything directly related to the title, let´s talk (or write) about today´s case:

Cat´s Cry Syndrome: Partial Deletion of Chromosome 5

Going back(briefly, before I get all tangled up in it) to the metaphor I have been using, sometimes the malfunctions of a machine are not caused by structural damage or deterioration of the parts, but by factory defects that occur in 1 out of every 100,000 assemblies. Something similar can happen in living organisms, exchanging the factory by the uterus, and the assembly process for that period of 9 months in which we are parasites sucking the vital force of our poor mother. During the gestation period, defects and imperfections can occur, sometimes due to things such as the mother's consumption of alcohol, drugs or other substances, or trauma to the stomach (it is not a good idea to practice martial arts during pregnancy. I know, have I not told you it would never have occurred to you), but sometimes, these problems in embryonic development come from before even that.

Chromosomes are basically the storage of the building blocks of your body; part of the materials that are used to create the embryo. This process is, of course, infinitely more complicated than that, but if I explain it in depth you would probably stop reading this article and go watch memes on Instagram, so I'll try to be direct and concise. These chromosomes contain our genome, which is a set of hundreds or thousands of genes that in turn are made of deoxyribonucleic acid, or DNA. The chromosomes are found inside the nucleus of the cell, and in the case of humans, they are present in the number of 23 pairs, or 46 per cell. However, life being as cruel and unfair as it is, there may be chromosomal defects, both in their quantity and in their structure, which cause problems in embryonic development, manifesting themselves as physical malformations, organ dysfunctions, mental retardation, or love for pineapple pizza. These pathologies are what we call genetic disorders.


And finally arriving at the true subject of this article, one of these genetic disorders is the so-called Cat´s Cry Syndrome, also known as cri-du-chat syndrome, because everything sounds better in French. It occurs in 1 in 20,000 to 50,000 births, and it is caused by a deletion of the short arm of the 5th chromosome (remember that these are X-shaped, with two short arms and two long arms). It is generally not hereditary; normally it occurs as a random event during the formation of the egg or sperm, or in the early stages of embryonic development. However, in 10% of the cases it can be inherited from one of the parents, who was a carrier of the chromosomal defect but did not present symptoms, since the genetic material that would normally be lost with the deletion of the short arm was moved to another part of the chromosome, in a process called balanced translocation.


Its symptoms and manifestations depend on the size of the deletion, and the amount of genetic material lost. The characteristic sign of the disease, and the one that gives it its name, is a sharp cry very similar to the meow of a cat that afflicted children emit from the time of birth until a few weeks after childbirth, then it disappears (although the name of the disease stays the same, once it sticks, why change it?). In addition to this, children who suffer from it also tend to be born with a lower weight than normal, a decreased muscle tone (hypotonia), and a smaller head than usual (microcephaly). They also usually have a very distinctive facial structure: a round face with widely spaced eyes, low set ears, a broad-based nose, strabismus, a jaw smaller than normal, and fused fingers or toes (syndactyly). Heart defects of various types are also frequent, and there is always mild to moderate mental retardation. People with this disease can reach adulthood, although life expectancy is relatively short.

Common physical manifestations of the condition

For its diagnosis, in addition to the characteristic clinic signs, genetic tests can be performed on the parents, to detect if they are asymptomatic carriers of the chromosomal malformation, in those afflicted to confirm the existence of the illness, and even in the embryo during pregnancy , to know if the disease will be present after birth. The cat´s cry syndrome does not have a specific treatment, but the usual procedure is to give as much support to the family as possible, from the moment of diagnosis. They are educated about the origin of the disease and the management of the afflicted person, and they are given access to support groups. The patient is monitored nutritionally since birth, to ensure that malnutrition does not occur. In addition, rehabilitation methods are offered in the form of psychological, occupational, and speech and language therapies. For heart defects or strabismus, corrective surgeries can be performed.


The majority of these genetic disorders are incurable, although it is possible to detect the genetic predisposition in time and make the decision of not having children that could end up suffering from the disease. However, genetic therapy is the most effective method to prevent the development of this condition, being able to eliminate the chromosomal defect and making safe the decision of having offspring. Someday, advances in this technique could completely eliminate genetic and hereditary diseases, and even allow us to make improvements in our genes, advancing the evolution of the human race (and making sure that no one ever thinks again about putting pineapple in a pizza). Oh science, what would we do without you?

References

• Beers & Mark H., et al. The Merck Manuals of Diagnosis and Therapy (11th edition). 2007.
• CerrutiMainardi, P. Cri-du-chat Syndrome. Orphanet Journal of Rare Diseases. 2006.
  
  
  If you enjoy medical-themed articles, or general curiosities, remember to follow me, there is much more on the way! And as always, I leave my thanks to @steemstem and @air-clinic for their constant support to all scientific content; you inspire us to keep improving.