eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Williams Syndrome

Author: Lennox H Huang, MD, Associate Clinical Chair, Assistant Professor, Department of Pediatrics, McMaster University; Deputy Chief of Pediatrics, McMaster Children's Hospital
Coauthor(s): Aneal Khan, MD, MSc, FRCP(C), FAAP, FCCMG, Assistant Professor of Medical Genetics and Pediatrics, University of Calgary; Consulting Staff, Departments of Pediatrics and Medical Genetics, Alberta Children's Hospital, Canada; Nathaniel H Robin, MD, Professor, Departments of Genetics and Pediatrics, University of Alabama at Birmingham; Consulting Staff, University of Alabama at Birmingham University Hospital and Children's Hospital of Alabama
Contributor Information and Disclosures

Updated: Jul 16, 2008

Introduction

Background

Originally described independently by Williams and Beuren in 1961, Williams syndrome (WS) is a rare genetic condition. The clinical manifestations include a distinct facial appearance, cardiovascular anomalies, hypercalcemia, and a characteristic neurodevelopmental and behavioral profile.

Pathophysiology

In virtually all cases of williams syndrome, haploinsufficiency (loss of 1 of 2 copies) due to a deletion at chromosome band 7q11.23 that involves the elastin gene (ELN) is implicated. Most deletions are not detected through standard karyotyping but rather through fluorescent in situ hybridization (FISH) for a 2-Mb deletion.1,2,3 The size of the deletion can vary.4,5,6

Williams syndrome is not solely caused by elastin haploinsufficiency; the deletion involves a region that spans more than 25 genes and, hence, is considered a contiguous gene deletion syndrome.4,7 The cardiovascular and connective tissue pathology, as well as facial dysmorphology, is attributed to the elastin gene haploinsufficiency.8,9

Other genes under investigation for their role in the cognitive profile of Williams syndrome include LIMK1, GTF1IRD1, and GTF2I.10,11,12 However, genotype-phenotype correlations with genes other than elastin are not yet fully elucidated.13,7

Frequency

United States

Williams syndrome occurs in 1 per 20,000 births; cases are largely sporadic.

International

Frequency worldwide is the same as in the United States.

Mortality/Morbidity

Cardiovascular disease accounts for most early mortality associated with Williams syndrome. Overall, unexpected death is rare but is 25- to 100-fold higher than in age-matched control subjects.14 Factors implicated in sudden death have included supravalvar aortic stenosis (SVAS), severe pulmonary stenosis, and myocardial ischemia secondary to either coronary insufficiency or biventricular outflow tract obstruction with ventricular hypertrophy. Coronary insufficiency appears most likely because of stenosis that results from intimal fibrosis and muscular hypertrophy.

Deaths have been reported after induction of anesthesia for minor surgical procedures, during cardiac catheterization and heart surgery, and with progressive heart failure and respiratory infection.15,14,16 Sudden deaths with no apparent instigating event have also been reported, with apparent underlying myocardial injury.15 Patients with a higher risk of sudden death may show signs of myocardial ischemia on electrocardiography (such as ST segment depression). Echocardiography, Holter monitoring, and careful evaluation should be considered before the use of anesthesia, sedation, or both or prior to an invasive procedure. Patients have also presented with syncope related to SVAS who died during diagnostic cardiac catheterization. Calcified valvular aortic stenosis has also been reported but not with sudden death.17,18

Sigmoid diverticulitis in adults is reported at a higher frequency in the Williams syndrome population than in the general population.19

Williams syndrome is a multisystem condition with other potential consequences, including mental retardation, motor delay, hearing loss, severe dental disease, ocular problems, progressive joint contractures, and bowel and bladder diverticula.

Race

Williams syndrome is panethnic. The prevalence of particular features may vary among populations; for instance, peripheral pulmonary stenosis is more common than SVAS in the Hong Kong Chinese population,20 and people living in Greece have a lower rate of cardiovascular anomalies.21

Sex

The deletion is equally prevalent in males and females. A greater severity and earlier presentation of cardiovascular disease may be observed in males.22,23

Age

Clinical manifestations of Williams syndrome are evident from birth through adulthood. However, features that may be detected antenatally include the characteristic cardiovascular lesions. In addition, fetal ultrasonography of neonates with Williams syndrome has revealed multicystic dysplastic kidney in addition to the congenital heart lesions.24 Associated findings on prenatal screening that have been reported include an increased fetal nuchal translucency and low maternal serum alpha fetoprotein (MSAFP); however, none of the prenatal findings has been proven to be a diagnostic marker of Williams syndrome.

Clinical

History

The history obtained from caregivers of patients with Williams syndrome varies and reflects the wide phenotypic spectrum observed in the syndrome. The neurodevelopmental profile primarily involves 4 areas: cognitive development, language, auditory function, and visuospatial function.25

  • Children with Williams syndrome are described as overly friendly, hyperactive, inattentive, and hypersensitive to loud sounds or certain types of sounds.26,27
  • Intellectual, motor, and language skills are typically delayed. Children with Williams syndrome typically have mild-to-moderate mental retardation, but the range includes severe mental retardation to average intelligence.25 Abilities should be considered on an individual basis due to the wide variability among individuals.28 Impaired motor development is often apparent before age 42 months.29
  • Older children have relative strengths in language and auditory memory with significant weaknesses in visual-spatial cognition.
  • As many as half of all children with Williams syndrome may exhibit autism spectrum social and communicative deficits.30
  • Visual-spatial problems may present as gait apraxia, especially on uneven or sandy surfaces.31
  • A history of hearing deficits and visual disturbances is possible.
  • Adults may have a high rate of emotional and behavioral problems, poor social relationships and anxiety, preoccupations and obsessions, and communication disturbances. Few adults achieve complete independence.32,33,34
  • In children, a history of increased urinary frequency and daytime wetting is possible.35 A history of renal abnormalities is also possible.
  • Children may have a history of postnatal growth delay, including short stature with delayed bone age,36 growth hormone deficiency,37 and decreased insulinlike growth factor–1 (IGF1) levels.38,39
  • A history of hypertension may be noted.
  • A history of connective tissue abnormalities, such as abnormal joint mobility, hernias, and diverticula, is possible.

Physical

Phenotypic expression of Williams syndrome widely varies. Virtually all cases have typical facial features that can be recognized even at birth.

  • Children with Williams syndrome are generally full-term infants.
  • Microcephaly is observed in one third of children,40 and postnatal failure to thrive is typical.
  • The diagnosis of Williams syndrome should also be considered after an incidental finding of idiopathic hypercalcemia or a characteristic cardiac lesion such as SVAS. Other cardiac lesions in patients with Williams syndrome can include pulmonary stenosis and mitral valve regurgitation.32,23 Arterial hypertension may be present. If the distinct facial features are not evident, consider referral to a practitioner experienced in examining the facial features of Williams syndrome, such as a clinical geneticist or cardiologist experienced in dysmorphology.
  • Virtually all children and adults with Williams syndrome have some combination of the following facial features: short upturned nose, flat nasal bridge, long philtrum, flat malar area, wide mouth, full lips, dental malocclusion and widely spaced teeth, micrognathia, stellate irides, and periorbital fullness. The voice may be harsh. Nails tend to be hypoplastic and the skin soft and lax, and the hallices have a valgus deviation. "Elfin facies" is considered a pejorative term, and its use should be discouraged.
  • Ocular findings can include strabismus (usually due to esotropia), a stellate iris, cataract, retinal vascular tortuosity, and reduced binocular vision; a case of Reiger anomaly has even been reported.41,42,22
  • Sensorineural hearing loss can be present and is likely underdiagnosed.43 It can be aggravated by conductive loss due to middle ear effusions.
  • Examine patients for signs of precocious puberty.
  • Other findings include hyperacusis (despite hearing loss), hoarse voice, joint hyperelasticity, contractures, kyphoscoliosis, and lordosis.
  • Monitor for hypertension at every visit.

Causes

A deletion on band 7q11.23 near the elastin gene is identified in virtually all individuals with Williams syndrome. The underlying etiology is believed to be unequal meiotic crossover events that lead to interstitial deletions.44,45 These deletions may result in unbalanced interchromosomal and, to a lesser extent, intrachromosomal rearrangements. Mechanisms whereby chromosomes paired during meiosis may undergo unequal crossover resulting in Williams syndrome have typically been thought to result from an unequal overlap of repetitive Alu sequences flanking the region, resulting in a type of misalignment of the chromosomal regions during a crossover event.46 In addition, another mechanism that has recently been shown includes a familial inversion polymorphism in the Williams syndrome region that may predispose to unequal crossover during meiosis.47

More on Williams Syndrome

Overview: Williams Syndrome
Differential Diagnoses & Workup: Williams Syndrome
Treatment & Medication: Williams Syndrome
Follow-up: Williams Syndrome
References
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References

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Further Reading

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Keywords

Williams syndrome, WS, Williams' syndrome, Williams-Beuren syndrome, elfin facies syndrome, hypercalcemia, mental retardation, microcephaly, failure to thrive, pulmonary stenosis, mitral valve regurgitation, supravalvar aortic stenosis, SVAS, short upturned nose, flat nasal bridge, long philtrum, flat malar area, wide mouth, full lips, dental malocclusion, widely spaced teeth, micrognathia, stellate irides, periorbital fullness, attention deficit hyperactivity disorder, ADHD, sigmoid diverticulitis, multicystic dysplastic kidney, hypertension, short stature, growth hormone deficiency, abnormal joint mobility, hernias, diverticula, precocious puberty

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Contributor Information and Disclosures

Author

Lennox H Huang, MD, Associate Clinical Chair, Assistant Professor, Department of Pediatrics, McMaster University; Deputy Chief of Pediatrics, McMaster Children's Hospital
Lennox H Huang, MD is a member of the following medical societies: American Academy of Pediatrics, Canadian Medical Association, Ontario Medical Association, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Aneal Khan, MD, MSc, FRCP(C), FAAP, FCCMG, Assistant Professor of Medical Genetics and Pediatrics, University of Calgary; Consulting Staff, Departments of Pediatrics and Medical Genetics, Alberta Children's Hospital, Canada
Aneal Khan, MD, MSc, FRCP(C), FAAP, FCCMG is a member of the following medical societies: American Academy of Pediatrics, American Society of Human Genetics, Canadian Medical Association, Canadian Paediatric Society, and Ontario Medical Association
Disclosure: Nothing to disclose.

Nathaniel H Robin, MD, Professor, Departments of Genetics and Pediatrics, University of Alabama at Birmingham; Consulting Staff, University of Alabama at Birmingham University Hospital and Children's Hospital of Alabama
Nathaniel H Robin, MD is a member of the following medical societies: American Cleft Palate/Craniofacial Association, American College of Medical Genetics, American Society of Human Genetics, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Medical Editor

Jeffrey Allen Towbin, MD, MSc, FAAP, FACC, FAHA, Professor, Departments of Pediatrics (Cardiology), Cardiovascular Sciences, and Molecular and Human Genetics, Baylor College of Medicine; Chief of Pediatric Cardiology, Foundation Chair in Pediatric Cardiac Research, Texas Children's Hospital
Jeffrey Allen Towbin, MD, MSc, FAAP, FACC, FAHA is a member of the following medical societies: American Academy of Pediatrics, American Association for the Advancement of Science, American College of Cardiology, American College of Sports Medicine, American Heart Association, American Medical Association, American Society of Human Genetics, Cardiac Electrophysiology Society, Heart Rhythm Society, New York Academy of Sciences, Society for Pediatric Research, Texas Medical Association, and Texas Pediatric Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

Managing Editor

Ameeta Martin, MD, Clinical Associate Professor, Department of Pediatric Cardiology, University of Nebraska College of Medicine
Ameeta Martin, MD is a member of the following medical societies: American College of Cardiology
Disclosure: Nothing to disclose.

CME Editor

Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College
Gilbert Herzberg, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Chief Editor

Stuart Berger, MD, Professor of Pediatrics, Division of Cardiology, Medical College of Wisconsin; Chief of Pediatric Cardiology, Medical Director of Pediatric Heart Transplant Program, Medical Director of The Heart Center, Children's Hospital of Wisconsin
Stuart Berger, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American College of Chest Physicians, American Heart Association, and Society for Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

 
 
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