A developmental disorder

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William's Syndrome

William's syndrome is a developmental disorder with multisystem defects like congenital vascular and heart disease, dimorphic facial features, growth deficiency, infantile hypercalcemia, mental retardation, unique cognitive profile, and a characteristic personality.[1] It is estimated that Williams Syndrome affects 1 in 7,500 - 20,000 people.

William's syndrome (WS), also known as William's Beuern Syndrome, was first described by a cardiologist from New Zealand, Dr. J. C. P. Williams in 1961 working as a Registrar at Greenlane Hospital, Auckland. He noticed that individuals with William's Syndrome had heart and cardiovascular problems, high blood calcium levels, low birth weight, short stature and other abnormalities related to connective tissues. He also noticed that individuals with William's Syndrome often have some pattern of learning disability.

It is a result of a series of deletion of genes on chromosome 7q11.23(32) arising as a consequence of unequal recombination during meiotic crossing over. It is now known that the deletions may span as much as 250kb, presumably disrupting adjacent genes. [3] The deletion includes the elastin and 14 other genes. The deletion on elastin gene is responsible for connective tissue and cardiovascular abnormalities. The deletion of GTF2I (general transcription factor II, I) is consider to lower the IQ. Deletion on LIMK1 is thought to cause abnormality of visuospatial constructive cognition in William's Syndrome. [4] Scientists have also found that the WBSCR12 gene that encodes for 852 amino acid is deleted in WS patients and is thought to give certain characteristics to the patients as it is expressed in various regions of the brain and intestinal area. [5] The impact of deletion of other genes on humans still needs to be discovered.

The diagnosis of Williams's syndrome is confirmed by detecting contiguous gene deletion in chromosome 7, using Fluorescent In Situ Hybridization (or FISH). Non FISH based methods like real time quantitave PCR, Genomic Microarray Analysis or Heterozygosity testing can also be used to detect the gene deletions in critical area of chromosome 7. [4]

WS is considered to be an autosomal dominant disorder hence; offspring's have 50% chance of getting the disease. Prenatal tests are performed for pregnancies that are at 50% risk of getting WS at 10 to 12 weeks of pregnancy with to detect the critical region deletions. [4]

As William's Syndrome is a multi-system disorder in which individuals suffering from the disease have cardiovascular, growth, joint and other physical problems. They also share distinct facial features and personality traits.

Babies born with WS are often small and 70% fail to thrive during infancy. Those who survive face growth problems throughout their life and have short stature. Infants with WS can be extremely irritable and have 'colic-like' behaviour because of hypercalcemia (high concentration of calcium in blood). Other problems that occur during the early years of life are like strabismus (cross eyes), ear infections, eating problems and constipation. [6]

WS patients also have distinct facial features which are seldom described as 'elfin' or 'pixie like'. Individuals have small upturned nose, long philtrum (upper lip), wide mouth, full lips, puffiness around the eyes, widely spaced small teeth and small chin. These features become more prominent with age. Children with blue and green eyes can have a prominent 'starburst' or white lacy pattern on their iris.[7]

About 90% of the patients suffering from WS have dental aplasia [absence of all or a part of the organ due to defective development is called aplasia] and about 96% suffered from primary tooth resorption. Fan shaped positioning of front teeth is also seen in a majority of WS patients. [8] It is due to these abnormalities individuals suffering from William's Syndrome have small wide spaced teeth.

Patients with William's Syndrome often suffer from heart diseases. SupraValvar Aortic Stenosis [also known as SVAS is a heart condition where aorta is narrowed at the area close to its origin [9]] is the most common birth defect in the patients suffering from WS. The degree of narrowing is variable. [6] About 80% of the patients suffering from William's Syndrome have hear murmurs [extra heart sounds]. [10] It is important to seek medical attention for the SVAS as it can lead to high blood pressure, other heat diseases and even heart failure. The blood vessels that lead to the kidney and other organs can also be affected. [6] 59% of adult patients suffering from William's Syndrome suffer from hypertension. [11]

WS patients also suffer from infantile hypercalcemia. It generally occurs during the early years of life but may reoccur during the time of puberty. Patients feel very irritable, cannot feed themselves and constipation. It can be resolved with medical intervention and diet management during the acute phase. The cause of infantile hypercalcemia remains a mystery as calcium regulating genes are outside the deletion area of chromosome 7. [12]

Because of deletion of elastin gene urological problems like bladder diverticula [A defect where a part of the bladder lining forms a pouch in the muscle wall of the bladder], renal aplasia or hypoplasis and other urinary tract infections are present. A routine examination by a urologist is recommended as there is a high risk of getting urological problems. [13]

WS patients also suffer from disease related to connective tissues like inguinal hernia, bladder and bowel diverticulli [small pouches in the colon that budge outwards through weak spots in colon], hoarse voice and soft skin. Puberty usually occurs early with a brief growth spurt. [4]

As patients with get older their heel chords and hamstrings tend to tighten , which leads to stiff awkward gain and curving of spine. [6]

Approximately 75% of the patients that suffer from William's Syndrome show signs of mild mental retardation. They have unique learning abilities and disabilities. They generally have excellent language and memorization skills. They also have extensive vocabulary and may develop a vast knowledge of the subject they are interested in. Many are also gifted with great musical abilities. WS patients have difficulty with math, writing and drawing as they have trouble with concepts that use visuospatial ability. [6]

Children with William's Syndrome are extremely sociable, unusually friendly, charming, outgoing and highly concerned about the well beings of others. [14] In contrast to this some patients with William's Syndrome show behavioural and emotional disturbances. They show signs of anxiety, insecurity, hyperactivity, preservations, and inappropriate interpersonal behaviour. [15]

William's syndrome is usually diagnosed by a physician familiar with William's Syndrome. Infants with heart diseases especially SVAS are diagnosed for WS. In children with no heart problems diagnose is done when they are enrolled at school and they find difficult to learn or are slow learners. Diagnosis is done by physical examination and medical history. It is confirmed by a DNA test. FISH test is done to see if there is any genetic material that is missing. A FISH test will be positive in over 99% of individuals with WS. FISH can also be done in prenatal state by chronic villus sampling or by amniocentesis. Prenatal testing is only performed if there is a family history of William's Syndrome. [6]

Developmental disabilities related to WS addressed early through special education programs and vocational training. Recommended therapies like speech/language, physical and occupational are used to help the WS patients to master the daily living skills. Behaviour counselling is often used to mange behavioural problems especially, attention deficit disorder and anxiety. Self calming technique are used to manage anxiety. [16] [15]

SVAS can be treated surgically. About 30% of WS cases require surgical correction. [17] Hypertension is usually treated using drugs surgically. [16]

With the help of nutritionists hypercalcemia is managed by adjusting diet in a way that calcium intake is not higher than 100% of recommended daily allowance (RDA). Also, serum concentration of calcium should be monitored.

Dental care should be taken by regularly brushing and flossing teeth. Dental Cleaning should be done every few months. Constipation should be aggressively managed at all ages.

A regular exercise and balanced diet should be also taken to avoid dependence on insulin as many WS patients suffer from diabetes mellitus. [16]

In most cases the parents of an individual with William's Syndrome are not affected hence in absence of any clinical features FISH test is not required for the parents. 25% to 30% of cases of chromosome deletion has an inversion on chromosome 7 involving the WBSCR. [18] Testing for such inversions is available on a research basis only.

William's Syndrome patients paint a unique picture showcasing a wide range of talent irrespective of the troubles they go thorugh. With the advancement in technology the researches have designed programs to address the needs of those suffering from the disease. Dr. Ursula Bellugi has summed up the genetic disorder by saying - "People with William's Syndrome are smart and mentally retarded, gifted and inept at the same time"

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