Molecular cytogenetic diagnosis of Williams syndrome

Periodontal conditions in Williams Beuren syndrome: a series of 8 cases

BACKGROUND

Williams Beuren syndrome (WBS) is an unusual hereditary connective tissue disease caused by a microdeletion at position 7q11-23 and a haploinsufficiency at the elastin gene. The most frequent specific features are elf-like face, alteration of cognitive functions and cardiovascular diseases including isolated supravalvular aortic stenosis. A number of clinical findings have been reported, but none of the studies evaluating this syndrome consider the oral cavity. It is equally surprising that the gingival tissue, which carries a perfectly structured elastic fibre network, has not yet been investigated. It is important to verify whether subjects affected by WBS are more susceptible to periodontal disease than healthy subjects who are not that much affected, for periodontal disease may have deleterious effects on the cardiovascular system.

METHODS

In an attempt to address this issue, the oral manifestations of 8 patients (ages from 5 to 12 years) with WBS have been investigated: dental examination, periodontal examination (gingival phenotype, plaque control record, gingival index, bone quality).

RESULTS

All patients had oral parafunction, tooth number abnormalities and malocclusions. Average gingival height and width were greater than normal. Plaque index was always very high except for one patient, but the gingival inflammation was not linked to the quantity of clinical plaque index. There was no obvious loss of attachment.

CONCLUSION

As with collagen, elastin is a structural macromolecule of the gingiva. These components play an important role in gingival function and in the resistance of the periodontium to daily aggressions. Unlike genetic diseases characterized by impairment of collagen macrofibrils, it is suggested that the hemizygous gene encoding elastin does not result in periodontal disease. In addition there is an existence of a possible concordance between the elastin gene haploinsufficiency and the periodontal phenotype. There might be some adaptive process to this deficiency.

Outcome of pulmonary and aortic stenosis in Williams-Beuren syndrome in an Asian cohort

AIMS

To define the cardiovascular anomalies and the long-term outcomes in an Asian cohort with Williams-Beuren syndrome (WBS).

METHODS

Data were retrieved from a retrospective chart review of patients who had a definitive diagnosis of WBS by fluorescence in situ hybridization between 1995 and 2005. All patients underwent echocardiography every 3-9 months. Ten patients underwent cardiac catheterization.

RESULTS

Twenty-one patients with a total follow-up of 134 patient-years (median: 72 months) were enrolled. Characteristic dysmorphic facial features were noted in 19 patients (n = 19, 90%). All except one had associated cardiac anomalies, accounting for 0.3% (20/6640) of the patients with congenital heart disease. The spectrum of cardiac anomalies included supravalvular aortic stenosis (SVAS) (n = 15, 71%), peripheral pulmonary stenosis (PPS) (n = 12, 57%), pulmonary valve stenosis (PS) (n = 10, 47%), mitral valve prolapse (MVP) (n = 9, 43%), coarcation of the aorta (n = 4, 19%), ventricular septal defect (n = 2, 10%) and atrial septal defect (n = 1, 5%). Concurrent SVAS and PS/PPS were found in 14 (70%) patients. Only one patient required balloon dilation of PS, which improved. Regression of the stenoses occurred with a probability of 31, 90 and 71% at the age of 10 years for SAVS, PS and PPS, respectively.

CONCLUSIONS

Among our WBS patients, SVAS, PPS and PS were common, and were associated with probability of spontaneous regression, especially of right-sided lesions.

Severe coronary artery disease in the absence of supravalvular stenosis in a patient with Williams syndrome

Williams syndrome is a complex syndrome comprising developmental abnormalities, craniofacial dysmorphic features, and cardiac anomalies. The most common cardiac anomaly is supravalvular aortic stenosis. We report a case of a 6-year-old girl with Williams syndrome who presented with decompensated heart failure due to ischemic cardiomyopathy. Her only significant cardiac anomaly was severe stenosis of the left main coronary artery. She subsequently died despite surgical revascularization. Isolated coronary anomalies are rare in Williams syndrome but should be considered especially in the presence of heart failure or ischemia.

Williams syndrome: pediatric, neurologic, and cognitive development

This study examines the developmental history of 32 Williams syndrome patients, positive to the fluorescence in situ hybridization (FISH) test. The information is intended to provide help for early diagnosis and appropriate stimulation of these patients. In the sample reported here, only about half of the patients referred with presumptive diagnosis were in fact FISH+, indicating that facial dysmorphism may not be the most reliable sign for diagnosis. Initial pediatric signs are developmental delay and nocturnal irritability. In consultation, facial dysmorphies and heart murmur are detected. There is also low birth weight, failure to thrive, unsuccessful breastfeeding, and gastroesophageal reflux. All these symptoms are strongly suggestive of Williams syndrome. Subsequent steps consist of cardiologic studies. Our results indicate that the triad of symptoms consisting of infantile hypercalcemia, dysmorphic facies, and supravalvular aortic stenosis, which until recently was considered fundamental for Williams syndrome diagnosis, is not usually present and does not lead to an early diagnosis. Cognitively, these children are characterized by hypersociability, hyperacusia, deficient visuoconstructive abilities, attentional deficit and hyperactivity, and in some cases, spontaneous musical interests. There are no special verbal skills. The results of this study indicate that the concept of Williams syndrome patients as language- and musically-gifted is not fully accurate.

Anisomastia associated with interstitial duplication of chromosome 16, mental retardation, obesity, dysmorphic facies, and digital anomalies: molecular mapping of a new syndrome by fluorescent in situ hybridization and microsatellites to 16q13 (D16S419-D16S503)

Anisomastia is a common problem among developing adolescent girls. We recently evaluated a 22-yr-old female patient who had severe anisomastia (which had been repaired by surgery), associated with moderate to severe mental retardation, a stocky body habitus with mild obesity, dysmorphic facies (prominent, upslanting palpebral fissures, beaked nose, and a prominent philtrum), webbed neck, low hairline, and severe bilateral clinodactyly of the third, fourth, and fifth fingers with acral (but not large joint) flexion contractures. A peripheral blood high resolution karyotype revealed additional chromosomal material within the long arm of chromosome 16. Densitometric analysis of amplified polymorphic sequence-tagged sites (STS) mapping to 16q suggested that the duplication is defined by the noninvolved markers D16S419 [16q12-cen, 66 centimorgan (cM) from 16p terminus] and D16S421 (16q13-q21, 84.4 cM), encompassing a maximum of 18.4 cM of genetic distance. The STS analysis showed that the duplication was on the maternally derived chromosome 16, resulting in two maternal (and one paternal) copies of that region of chromosome 16. The location was further confirmed by bacterial artificial chromosomes (BACs) that were obtained from a commercially available library, labeled, and used for fluorescence in situ hybridization. The BACs containing STSs D16S408, D16S3137, and D16S3032 (markers that correspond to 16q13) showed two regions of hybridization, indicating that these sites were duplicated, whereas a BAC containing the STS D16S512 (which corresponds to 16q21-q22) revealed one hybridization signal per 16q, indicating that the corresponding region was not involved in the duplication. The distance between the probe signals suggested a tandem duplication. We conclude that even though trisomy 16 is the most common autosomal trisomy in spontaneous abortions, few patients with unbalanced chromosome 16 abnormalities survive to adulthood; in this report we describe one such patient with an interstitial chromosome 16 duplication (at 16q13), who had a specific phenotype associated with abnormal breast size. There are clinical similarities between this patient and patients with other 16q abnormalities, although the breast findings were unique. Molecular cytogenetics, including fluorescence in situ hybridization and densitometric analysis of amplified STSs, provided useful tools for the precise mapping of the syndrome to 16q13, where the gene(s) responsible for this phenotype might be localized.

Hemizygous deletion of the HPC-1/syntaxin 1A gene (STX1A) in patients with Williams syndrome

HPC-1/syntaxin 1A is a membrane protein that plays an important role in exocytosis of neurotransmitters from neuronal cells. We previously mapped the human HPC-1/syntaxin 1A gene (STX1A) to chromosome 7q11.2, which is within the Williams syndrome (WS) region. Here, we performed FISH analysis on 46 patients with WS to examine the relationship between STX1A and WS. Our results showed a hemizygous deletion of the HPC-1/syntaxin 1A gene in each patient, suggesting that the neurological symptoms of WS may be related to the hemizygous deletion of STX1A.