Williams syndrome

Williams syndrome. Williams syndrome or Williams-Beuren syndrome is a rare genetic disorder, caused by a loss of genetic material on chromosome 7, which was first described in 1961 by New Zealand cardiologist John Williams and in parallel by German pediatrician Alois Beuren.

Summary

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  • 1 History
  • 2 Denomination
  • 3 Incidence
  • 4 Symptoms
    • 1 Pathologies
    • 2 Mental development
    • 3 Conduct
    • 4 Emotional perception
    • 5 Spatial perception
    • 6 Leftism
    • 7 Musicality
    • 8 Physiognomy
  • 5 Causes
  • 6 Diagnosis
  • 7 Associated diseases
  • 8 Treatment
  • 9 Precautions
  • 10 Sources

History

This syndrome was first described in 1961 by Dr. JCP Williams, a New Zealand cardiologist who reported a complex clinical picture, the most prominent symptoms of which were a general delay in mental development, a characteristic expression of the face and a coronary defect from birth, known as aortic supravalvular stenosis (ESA) and consisting of a narrowing of the aorta near the heart.

At the same time, Professor Beuren, a pediatric specialist from the German city of Göttingen, reported several cases of ESA, presenting symptoms similar to those described by Dr. Williams. Later, in 1964 , Professor Beuren showed that narrowing of the pulmonary arteries (pulmonary peripheral stenosis or SP) also frequently appears in these clinical pictures.

Denomination

The picture described by both scientists is sometimes known in Europe as Beuren syndrome or Williams-Beuren syndrome, although it is increasingly known as Williams syndrome.

Incidence

It is a disorder of genetic origin, not hereditary, which occurs from birth in one of every 20,000 live births (according to estimates), which equally affects men and women, and which has no ethnic preference.

Symptoms

Symptoms of the syndrome are a set of specific medical pathologies, psychological disorders and external signs, which manifest during the development of the individual, generally not before the 2 or 3 years of life of the same, and which do not always converge all together. in the same person.

Pathologies

Cardiovascular problems such as supravalvular aortic stenosis and transient hypercalcemia are common.

Mental development

There is usually some kind of mental retardation. Language development Ease in language acquisition.

Conduct

Unusually joyous and calm demeanor may occur in front of strangers, coupled with unpredictable outbursts of bad humor or discomfort.

Emotional perception

Difficulty understanding the mental state of their interlocutors (empathy). This aspect has been put in relation to autism. However, people with Williams syndrome generally have very good social skills. In fact Temple Grandin, author of Thinking with Pictures: My Life with Autism, has stated that abnormalities in the brain of those with this syndrome are contrary to those of autism.

Spatial perception

Inability to visualize how different parts can be put together in order to create larger objects, for example the joining of puzzle pieces. A team of researchers from the National Institute of Mental Health used nuclear magnetic resonance imaging to observe brain blood flow in several individuals undergoing two tasks involving spatial relationships.

People with Williams syndrome showed less activity in the brain section associated with spatial relationships than people without syndrome. This indicates a tissue dispersion deficit in the brain’s visual system, which perceives spatial relationships. This deficit obstructs part of the transmission of visual information.

Another experiment documented that people with Williams syndrome, when shown an image, draw the small details but not the whole. In this way it can be generalized that patients with Williams syndrome “can see the trees, but not the forest.”

Leftism

Tendency to left-handedness and the use of the left eye.

Musicality

People who have the syndrome usually have a passion for music and absolute ear cases are more frequent in them.

Physiognomy

People with the syndrome often have a facial appearance called an elf, along with a low nasal bridge.

Causes

The cause of Williams Syndrome is a loss of some of the genetic material in band 7q11.23. of one of the two chromosomes 7 of the DNA , coming from the father or the mother. It is a submicroscopic loss, because it is not well appreciated when viewed under a microscope.

The alteration originates before the formation of the embryo, either in the ovule or in the sperm, after having suffered a loss of genes on chromosome 7 during its formation through cell division or meiosis. Therefore, as far as is known, it is not hereditary.

The number of genes lost has not yet been determined, but it is estimated that it ranges between 20 and 30, out of the 80,000 that exist. Loss of those genes can cause the functions they direct to not perform normally. However, not all the functions of the missing genes are abnormal since there is another complete chromosome in pair 7.

Much remains to be known about the genetic substrate of Williams syndrome, however it is known that one of the missing genes is the one that produces elastin, a protein that gives elasticity to blood vessels and other body tissues. Loss of this gene is harmful, because it seems that it is necessary to have both copies of it for the production of elastin in adequate amounts. The reduction in the supply of elastin could be responsible for several pathologies derived from Williams Syndrome, such as Supravalvular Aortic Stenosis (ESVA) and hernias, as well as the premature appearance of wrinkles. However, cognitive or behavioral alterations derive from the absence of other genes, such as WSTF and FKBP6,

Diagnosis

Maturational delay, the presence of a circulatory disorder, school failure or facial appearance are some of the indicators of the syndrome, which when detected by pediatricians, child cardiologists or neurologists, lead the patient to be referred to the geneticist, who diagnoses it. Currently it is possible to confirm the diagnosis by molecular methods in more than 95% of cases.

The most widely used diagnostic method, although not the only one possible, is called FISH (Fluorescent In Situ Hybridization). This test consists of applying a reagent on the region of chromosome 7q11.23, from a piece of DNA obtained from an individual cell, normally from the blood. Fluorescence appears when any gene on the pair of chromosomes 7 is not duplicated. An accurate and early diagnosis is essential to avoid unnecessary steps and to plan optimal follow-up and treatment measures.

 

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