Thyroid hemiagenesis and elevated thyrotropin levels in a child with Williams syndrome

Autoimmune Thyroid Disease in Specific Genetic Syndromes in Childhood and Adolescence

Autoimmune thyroid disease (ATD) is the most frequent cause of acquired thyroid dysfunction, most commonly presenting either as Hashimoto's thyroiditis or Graves' Disease. Hashimoto's thyroiditis is characterized by the presence of thyroid-specific autoantibodies, more commonly anti-thyroperoxidase antibodies in the serum and the typical inhomogeneous echostructure of the thyroid on a thyroid ultrasound examination. Hashimoto's thyroiditis can for a long time be accompanied by normal thyroid function and hypothyroidism can only progressively be established. Graves' disease is much less frequent in childhood and adolescence and presents with overt hyperthyroidism. After the onset of puberty, ATD affects females with a higher incidence than males, while during the prepubertal period there is not such a clear preponderance of affected females. ATD can occur either isolated or in the context of other autoimmune disorders, such as type 1 Diabetes mellitus (T1D), celiac disease, alopecia areata, vitiligo, etc. Especially at the pediatric age, a higher incidence of ATD is also observed in the context of specific genetic syndromes, such as trisomy 21 (Down syndrome), Klinefelter syndrome, Turner syndrome, or 22q11.2 deletion syndrome. Nevertheless, although thyroid dysfunction may also be observed in other genetic syndromes, such as Prader-Willi or Williams syndrome, the thyroid dysfunction in these syndromes is not the result of thyroid autoimmunity. Interestingly, there is emerging evidence supporting a possible link between autoimmunity and RASopathies. In this review article the incidence, as well as the clinical manifestation and accompanied pathologies of ATD in specific genetic syndromes will be presented and regular follow-up for the early identification of the disorder will be proposed.

Thyroid evaluation of children and adolescents with Williams syndrome in Zhejiang Province

BACKGROUND

The objective of the study was to describe the prevalence of abnormal thyroid function and volume in children and adolescents with Williams syndrome (WS) in Zhejiang Province, China.

METHODS

Thyroid function, including thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and thyroid antibodies (thyroid peroxidase and thyroglobulin) were measured in 83 patients with WS, aged 0.2-16.5 years. Twenty-three patients were followed for an average of 1.7 years (0.4-4.1), and multiple TSH determinations were considered. Thyroid ultrasonography was performed on 49 patients.

RESULTS

One patient was diagnosed with overt hypothyroidism, and 23 patients (27%) had subclinical hypothyroidism (SH). Thyroid antibodies were absent in all patients. In five age groups (0-1 years, 1-3 years, 3-6 years, 6-9 years, 9-18 years), the prevalence of patients with subclinical hypothyroidism was 25%, 28.5%, 44.4%, 16.7% and 4.7%, respectively. Through ultrasound examination, 21 patients (42%) were observed to have thyroid hypoplasia (TH), and there were no cases of thyroid haemiagenesis. The incidence rate of TH increased with age, rising from 20% in the youngest group to 66% in the oldest.

CONCLUSIONS

SH and TH is common in children and adolescents with WS. Yearly evaluation of thyroid must be performed in all patients in this population, regardless of the result of the neonatal screening. Age under 6 years and existing thyroid abnormalities are risk factors for developing SH, and a shorter follow-up interval is needed for screening in these individuals, SH is often self-limiting, and clinicians should be alert to overt hypothyroidism.

Thyroid Hemiagenesis: Incidence, Clinical Significance, and Genetic Background

CONTEXT

Thyroid hemiagenesis (THA) constitutes a rare, congenital disorder that is characterized by an absence of one thyroid lobe. Because the pathogenesis and clinical significance of this malformation remain undefined, specific clinical recommendations are lacking, especially for asymptomatic cases.

EVIDENCE ACQUISITION

The PubMed database was searched (years 1970 to 2017), and the following terms were used to retrieve the results: "thyroid hemiagenesis," "thyroid hemiaplasia," "one thyroid lobe agenesis," and "one thyroid lobe aplasia." Subsequently, reference sections of the retrieved articles were searched.

EVIDENCE SYNTHESIS

There is a noticeable susceptibility of subjects with THA to develop additional thyroid and nonthyroidal pathologies. In pathogenesis of concomitant thyroid pathologies, a chronic elevation in thyroid-stimulating hormone values may play an important role. Thus far, genetic studies failed to find a common genetic background of the anomaly, and the potential underlying cause was identified in a minority of the cases.

CONCLUSIONS

Patients with THA are prone to develop additional thyroid pathologies and theoretically might benefit from l-thyroxine treatment to lower the thyrotropin levels to those observed in the normal population. However, further research should be done to ascertain whether such intervention early in life would prevent development of associated thyroid conditions. At least, increased vigilance should be maintained to reveal all of the concomitant disorders as soon as possible during follow-up examinations. Application of high-throughput technologies enabling a genome-wide search for novel factors involved in thyroid embryogenesis might be the next step to expand the knowledge on THA pathogenesis.

Mutations in proteasome-related genes are associated with thyroid hemiagenesis

PURPOSE

Human thyroid development is a complex and still unexplained process. Thyroid hemiagenesis is a congenital anomaly, where one of the thyroid lobes fails to develop. In the majority of patients with thyroid hemiagenesis, the genetic background remains unknown. The aim of the study was to search for novel genetic contributors to the etiology of thyroid hemiagenesis.

METHODS

A cohort of 34 sporadic patients diagnosed with thyroid hemiagenesis and one three-generation family were subjected to comprehensive genomic examination. Initially, targeted screening of associated transcription factors, known to be linked to thyroid development, was performed. As a next step, genomic examinations were applied using high-resolution microarrays, whereas for the thyroid hemiagenesis family, additionally the whole exome sequencing was performed.

RESULTS

Screening of transcription factors revealed no causative mutations in the studied cohort. Genomic examinations revealed the presence of four recurrent defects (three deletions and one duplication) affecting highly conservative proteasome genes PSMA1, PSMA3, and PSMD3. In a thyroid hemiagenesis family a splice site mutation in a proteasome gene PSMD2 (c.612T > C cDNA.1170T > C, g.3271T > C) was found in both affected mother and daughter.

CONCLUSIONS

Our results shed a new light on etiology of thyroid hemiagenesis, so far suspected to be linked only to mutations in the genes directly involved in the thyroid development. We demonstrated, for the first time, that genomic alterations in proteasome-associated genes co-occur in patients presenting this developmental anomaly.

Seven cases with Williams-Beuren syndrome: endocrine evaluation and long-term follow-up

BACKGROUND

Endocrine evaluation and long-term follow-up of seven (six male) patients with Williams-Beuren syndrome (WBS) are given.

METHOD

Data were obtained from patients' medical records. All patients underwent hormonal analyses and four of them underwent oral glucose tolerance test (OGTT).

RESULTS

They all had mild hypercalcemia. Three of them had overt hypothyroidism while subclinical hypothyroidism was detected in three patients. Four patients had thyroid hypoplasia and one had thyroid agenesis. Growth hormone deficiency (GHD) was determined in one patient. Impaired glucose tolerance (IGT) was found in three adolescents. All adolescents had early-onset puberty. The follow-up duration was 5.7±2.1 years. The mean growth velocity (GV) was 12.9±7.2 cm and 7.6±2 cm at the end of the first and second years of therapy, respectively. All patients had neurodevelopment retardation and were continuing to special education.

CONCLUSIONS

Thyroid hypoplasia is common and agenesis can be seen in patients with WBS; therefore, thyroid hormones should be measured in the newborn period and annually. GHD should be kept in mind in patients with decreased GV. IGT might be detected in patients with WBS even in adolescence.

Anesthesiological Management of a Patient with Williams Syndrome Undergoing Spine Surgery

Williams Syndrome (WS) is a complex neurodevelopmental disorder associated with a mutation on chromosome 7. Patients with WS usually display dysmorphic facial and musculoskeletal features, congenital heart diseases, metabolic disturbances and cognitive impairment. Structural cardiovascular abnormalities are present in the majority of the children and may provide a substrate for perioperative Sudden Cardiac Death, as presented by several reports, something that creates a great challenge to the anesthetic conduct. We present the case of a 12-year old girl who required anesthetic care for surgical correction of an acquired kyphoscoliosis. Potential anesthesiological implications of WS are subsequently reviewed.

Does TSH Trigger the Anti-thyroid Autoimmune Processes? Observation on a Large Cohort of Naive Patients with Thyroid Hemiagenesis

Thyroid hemiagenesis (THA) is a rare abnormality characterized by the absence of one thyroid lobe. Elevated thyroid stimulating hormone (TSH) level and higher incidence of thyroid diseases were reported in THA. The aim of the study is to evaluate the thyroid autoimmunity incidence in patients with THA and influence of higher than average TSH level on thyroid volume (TV) and its change with age. The study included a group of naive patients with THA and a control group of subjects with bilobate thyroid. All patients underwent clinical examination, thyroid ultrasound, scintiscan and laboratory tests. In the studied and control group the presence of thyroid autoantibodies (TAb) was evaluated. The THA group consisted of 65 patients. In THA group 53.85 % of patients were positive for TAb. Patients with positive TAb were older (46.0 ± 18.3 years) than those with negative (35.0 ± 19.8 years); p = 0.02. The incidence of TAb was lower in controls (13.85 %, p < 0.0001). In the study group, positive correlation between the age and TV (r = 0.46, p = 0.0001), and negative correlations between the age and TSH level (r = −0.31, p = 0.01), and TSH concentration and TV (r = −0.35, p = 0.004) were found. In a subgroup of 30 patients with THA negative for TAb, even stronger correlations were observed. The median single lobe volume and median TSH level were higher in patients with THA when compared to controls (13.60 vs 8.20 ml, p < 0.0001; 3.23 vs 1.48 µU/ml, p < 0.0001, respectively). Patients with THA constitute an in vivo model of long-term thyroid TSH overstimulation. Further studies are needed to reveal, whether TSH overstimulation may be the trigger for thyroid autoimmunity.

Bilateral vocal cord paralysis and hypothyroidism as presenting symptoms of Williams-Beuren syndrome: a case report

Williams-Beuren syndrome is a rare neurodevelopmental disorder caused by deletion of 1.5-1.8Mb genes on chromosome 7q11.23. The syndrome was first described as a triad of supra-valvular aortic stenosis, mental retardation, and distinctive facial features. Our patient was referred due to audible inspiratory stridor when he was seven days old. Following endoscopy he was diagnosed with bilateral vocal cord paralysis and was eventually intubated due to respiratory de-compensation followed by tracheotomy. On further workup he was diagnosed with hypothyroidism. Genetic workup supported the diagnosis of Williams-Beuren syndrome. We report here a case with an unusual clinical presentation.

New height, weight and head circumference charts for British children with Williams syndrome

AIM

To produce a growth reference for British children with Williams syndrome.

METHODS

The children and adults recruited into the study were all affiliated to the Williams Syndrome Foundation, a parent support group founded in 1979. They have all been shown to have a deletion of chromosome 7q11.23. One growth nurse (WRS) prospectively measured the weight, height and head circumference of individuals from 19 regions in Great Britain including Scotland, England and Wales. 169 children and adults were measured on up to four occasions between 2001 and 2004 (275 measurements). In addition, retrospective data were obtained from the hospital notes of 67 of these individuals (586 measurements). Centile curves were constructed using Cole's LMS method.

RESULTS

The centile charts differ from charts previously derived in the USA and Germany and provide more appropriate standards for the British population.

CONCLUSIONS

We propose that these charts be adopted for routine clinical practice as abnormalities in growth are an important feature of this syndrome.

Genetic basis for congenital heart defects: current knowledge: a scientific statement from the American Heart Association Congenital Cardiac Defects Committee, Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

The intent of this review is to provide the clinician with a summary of what is currently known about the contribution of genetics to the origin of congenital heart disease. Techniques are discussed to evaluate children with heart disease for genetic alterations. Many of these techniques are now available on a clinical basis. Information on the genetic and clinical evaluation of children with cardiac disease is presented, and several tables have been constructed to aid the clinician in the assessment of children with different types of heart disease. Genetic algorithms for cardiac defects have been constructed and are available in an appendix. It is anticipated that this summary will update a wide range of medical personnel, including pediatric cardiologists and pediatricians, adult cardiologists, internists, obstetricians, nurses, and thoracic surgeons, about the genetic aspects of congenital heart disease and will encourage an interdisciplinary approach to the child and adult with congenital heart disease.

Thyroid morphology and subclinical hypothyroidism in children and adolescents with Williams syndrome

OBJECTIVE

To verify the prevalence of morpho-volumetric and functional thyroid abnormalities in young patients with Williams syndrome (WS).

STUDY DESIGN

Ninety-two patients with WS (49 boys and 43 girls, 0.2-17.2 years of age) underwent evaluation of thyroid function by means of thyroid-stimulating hormone (TSH), fT3, and fT4 measurement. Thyroid ultrasonography was performed in 37 patients. Thyroid antibodies (thyroid peroxidase and thyroglobulin) were measured in all patients with abnormal thyroid function tests.

RESULTS

None of our patients had overt hypothyroidism; 29 patients (31.5%) had subclinical hypothyroidism. Thyroid antibodies were absent in all patients. The prevalence of patients with subclinical hypothyroidism was significantly higher in the younger patients. Ultrasonography revealed morphological or volumetric abnormalities of the thyroid gland in 67.5% of patients; these abnormalities were more frequently observed in the older children.

CONCLUSIONS

Subclinical hypothyroidism is a frequent but stable finding in young children with WS. The great majority of patients with WS >10 years, either with normal or hypoplastic thyroid, have normal thyroid function. Therefore, we suggest yearly monitoring of thyroid function and sonographic studies at least once in patients with WS. Treatment should be reserved for the patients with overt hypothyroidism or for those whose thyroid function shows signs of progressive deterioration.

Thyroid anomalies in Williams syndrome: investigation of 95 patients

Thyroid involvement in Williams syndrome (WS) was recently reported in two small groups of patients, both showing an increased prevalence of elevation of TSH serum concentration; in one of the two reports, 70% of the patients demonstrated a hypoplasia of thyroid gland as well. In our institution, we currently follow a large population of WS patients who periodically undergo a multispecialist clinical evaluation that includes ultrasound evaluation of the thyroid gland, and levels of FT3, FT4, TSH, and anti-thyroid antibodies. Here, we report on the prevalence of thyroid structural and functional anomalies, in a population of 95 WS patients, half of them followed for more than 5 years. Our study confirms the increased incidence of both elevated TSH serum values (37.9% in our sample) and thyroid gland hypoplasia (74.7%). Moreover, we demonstrated that TSH elevation declines with age. For this reason, we suggest that a complete thyroid evaluation be performed in every patient with WS, and that this medical complication should be periodically searched for in follow-up visits.

Neural mechanisms in Williams syndrome: a unique window to genetic influences on cognition and behaviour

Williams syndrome, a rare disorder caused by hemizygous microdeletion of about 28 genes on chromosome 7q11.23, has long intrigued neuroscientists with its unique combination of striking behavioural abnormalities, such as hypersociability, and characteristic neurocognitive profile. Williams syndrome, therefore, raises fundamental questions about the neural mechanisms of social behaviour, the modularity of mind and brain development, and provides a privileged setting to understand genetic influences on complex brain functions in a 'bottom-up' way. We review recent advances in uncovering the functional and structural neural substrates of Williams syndrome that provide an emerging understanding of how these are related to dissociable genetic contributions characterized both in special participant populations and animal models.

The developing mouse thyroid: Embryonic vessel contacts and parenchymal growth pattern during specification, budding, migration, and lobulation

Normal mouse thyroid development has been revised to identify critical morphogenetic events. The early thyroid primordium associates with the aortic sac endothelium at the time of specification and budding. The vascular contact is lost after the thyroid buds from the pharyngeal endoderm, but is resumed before the gland divides to form two lobes. Lateral expansion of parenchyma takes place along the course of the third pharyngeal arch arteries. Thyroid precursor cells expressing Titf1/Nkx2.1 do not proliferate until the migration stage, implicating that progenitors likely are recruited from outside the thyroid placode. Early lobulation involves engulfment of the entire ultimobranchial bodies by the growing midline thyroid. At the same time, proliferation of the ultimobranchial body epithelium is silenced preceding the differentiation of C cells. Before folliculogenesis, thyroid lobe enlargement is reminiscent of a budding-branching-like growth pattern. It is suggested that thyroid inductive signals arise from embryonic vessels, and that this provides ideas to conceptually new pathogenetic mechanisms of thyroid dysgenesis.

A mouse model demonstrates a multigenic origin of congenital hypothyroidism

Congenital hypothyroidism with thyroid dysgenesis (TD) is a frequent human condition characterized by elevated levels of TSH in response to reduced thyroid hormone levels. Congenital hypothyroidism is a genetically heterogeneous disease. In the majority of cases studied, no causative mutations have been identified and very often the disease does not show a Mendelian transmission. However, in approximately 5% of cases, it can be a consequence of mutations in genes encoding the TSH receptor or the transcription factors TITF1, FOXE1, or PAX8. We report here that in mouse models, the combination of partial deficiencies in the Titf1 and Pax8 genes results in an overt TD phenotype that is absent in either of the singly deficient, heterozygous mice. The disease is characterized by a small thyroid gland, elevated levels of TSH, reduced thyroglobulin biosynthesis, and high occurrence of hemiagenesis. The observed phenotype is strain specific, and the pattern of transmission indicates that at least two other genes, in addition to Titf1 and Pax8, are necessary to generate the condition. These results show that TD can be of multigenic origin in mice and strongly suggest that a similar pathogenic mechanism may be observed in humans.

Thyroid function and morphology in patients affected by Williams syndrome

OBJECTIVE

To evaluate the prevalence of abnormalities of thyroid function and morphology in a cohort of patients with Williams syndrome (WS).

METHODS

Serum concentrations of free-T3, free-T4, TSH, thyroperoxidase antibodies (TPOA) and thyroglobulin antibodies (TgA), as well as ultrasonographic data, of 20 patients with WS (12 females and eight males), aged 1.7-34.9 years, were evaluated.

RESULTS

Three cases (15%) of subclinical hypothyroidism were identified. Overt hypothyroidism was diagnosed in two cases (10%). Thyroid antibodies were negative in all patients. Fourteen patients (70%) showed thyroid hypoplasia involving the entire gland. In these patients, the left thyroid lobe appeared usually, but not significantly, reduced compared with the right thyroid lobe. One patient (5%) showed thyroid hemiagenesis. Only five patients (25%) showed a thyroid with normal volume, and of these five, one patient showed marked thyroid hypoplasia of the left lobe. In all WS patients with diagnosis of subclinical or overt hypothyroidism, thyroid hypoplasia was detected. No cases of subclinical or overt hypothyroidism were found in WS with normal thyroid volume.

CONCLUSIONS

This study confirms the presence of alterations of thyroid function in WS and also suggests the frequent occurrence of abnormalities of thyroid morphology in these patients. Patients with WS should be monitored for thyroid function and a thyroid ultrasound screening should be considered, especially in those patients with changes in thyroid function.

Clinical manifestations and molecular investigation of 50 patients with Williams syndrome in the Greek population

Williams syndrome (WS) is a well-recognized neurodevelopmental disorder manifested by both connective tissue and CNS abnormalities. The study depicts the 8-y experience and follow-up of 50 Greek children with the clinical diagnosis of WS. Clinical data on the facial features and cardiovascular, endocrinologic, and neurodevelopmental evaluation are presented. The most consistent findings were dysmorphic features (100%), followed by dental anomalies (90%) and hyperacousis (90%). Only eight of 50 children had severe cardiovascular defects that required surgical intervention during the first year of life. Supravalvular aortic stenosis was less frequent (28%) than shown in the literature. Severe hypertension was noticed in 22% of our patients, and infantile hypercalcemia was noticed in 6%. Twelve percent of our patients showed an elevation of CPK. Most children presented with moderate to severe mental retardation with IQ ranging from 20 to 85. Elastin hemizygosity was detected by fluorescence in situ hybridization. Dinucleotide repeat polymorphism analysis was performed in an attempt to correlate phenotype with genotype. The origin of deletions was more frequently maternal (59%), and a more severe phenotype seemed to be associated with those deletions. This is the first report on WS patients in the Greek population.

Perioperative care of the patient with Williams syndrome

Williams syndrome, initially described by Williams, Barratt-Boyes, and Lowe in 1961, consists of characteristic dysmorphic features, congenital heart disease, and distinctive behavioral and emotional traits. In addition to acquired and congenital heart disease, manifestations in the renal, endocrine, musculoskeletal, and central nervous system may have implications during the perioperative period. Congenital and acquired heart disease can be a significant issue as sudden death, related to abnormalities of the coronary arteries, has been reported perioperatively in these patients. The authors present a 7-month-old infant, previously diagnosed with Williams syndrome, who required anesthetic care for repair of subaortic and supravalvular aortic stenosis. The potential perioperative implications of Williams syndrome are discussed.

Thyroid hemiagenesis and incidentally discovered papillary thyroid cancer: case report and review of the literature

Thyroid hemiagenesis (TH) is a rare congenital abnormality in which one thyroid lobe fails to develop. Its prevalence is uncertain, because the absence of one thyroid lobe does not usually cause clinical symptoms. The detection of TH is usually incidental when the evaluation of other thyroid disorders is requested. It is more frequently found in female than in male patients (3:1 ratio) and in the left lobe compared to the right lobe. We report the case of a 54-yr-old man, presenting with a large multinodular right-sided goiter, with mediastinal extension and dysphagia. Thyroid scan and ultrasound study showed the absence of the left lobe. The patient underwent surgery for compressive symptoms, and the operation confirmed the absence of the left lobe. Histological examination demonstrated a multi-nodular goiter with papillary carcinoma. To our knowledge, this case represents the first reported case of association between TH and papillary thyroid carcinoma in a male patient, and the second in which the tumor arose in the right lobe.

Neural Basis of Genetically Determined Visuospatial Construction Deficit in Williams Syndrome

A unique opportunity to understand genetic determinants of cognition is offered by Williams syndrome (WS), a well-characterized hemideletion on chromosome 7q11.23 that causes extreme, specific weakness in visuospatial construction (the ability to visualize an object as a set of parts or construct a replica). Using multimodal neuroimaging, we identified a neural mechanism underlying the WS visuoconstructive deficit. Hierarchical assessment of visual processing with fMRI showed isolated hypoactivation in WS in the parietal portion of the dorsal stream. In the immediately adjacent parietooccipital/intraparietal sulcus, structural neuroimaging showed a gray matter volume reduction in participants with WS. Path analysis demonstrated that the functional abnormalities could be attributed to impaired input from this structurally altered region. Our observations confirm a longstanding hypothesis about dorsal stream dysfunction in WS, demonstrate effects of a localized abnormality on visual information processing in humans, and define a systems-level phenotype for mapping genetic determinants of visuoconstructive function.

Genetic deletion of sonic hedgehog causes hemiagenesis and ectopic development of the thyroid in mouse

Thyroid dysgenesis encountered in 85% of patients with congenital hypothyroidism is a morphologically heterogeneous condition with primarily unknown pathogenesis. Here we identify sonic hedgehog (Shh) as a novel regulator of thyroid development. In Shh knockout mice the thyroid primordium is correctly specified in the pharyngeal endoderm, but budding and dislocation are slightly delayed. In late development the thyroid fails to form a bilobed gland. Instead a single thyroid mass is found unilaterally and mostly to the left of the midline. Thyroid-specific transcription factors (TTF-1 and TTF-2) and thyroglobulin are expressed indicating terminal differentiation. Strikingly, TTF-1- and TTF-2-positive cells aberrantly develop in the presumptive trachea of Shh-/- embryos. The ectopic tissue buds ventrolaterally into the adjacent mesenchyme, and less extensively into the tracheal lumen, forming follicle-like structures that accumulate thyroglobulin. Shh mRNA is not expressed in the thyroid precursor cells at any developmental stage. The results indicate that Shh signaling indirectly governs the symmetric bilobation of the thyroid during late organogenesis. Shh also seems to repress inappropriate thyroid differentiation in nonthyroid embryonic tissues. This study provides clues to the molecular mechanisms that might be dysregulated in thyroid hemiagenesis and development of ectopic thyroid tissue outside the thyroglossal duct.

New case of thyroid dysgenesis and clinical signs of hypothyroidism in Williams syndrome

The authors report a female presenting with congenital heart defects, liver hemangiomas, and facial dysmorphisms admitted to hospital at 3 months of age because of feeding difficulties and poor growth. She had hypotonia and large tongue, "coarse" face, and umbilical hernia in presence of complex congenital cardiovascular malformations. In spite of normal neonatal screening we performed serum levels of thyroid hormones. Thyrotropin level was very high (>50 microU/ml; normal value 0.2-4 microU/ml), while serum free T(3) (FT3) and free T(4) (FT4) levels were normal (FT3 3.6 pg/ml, normal value 2.8-5.6 pg/ml; FT4 11.6 pg/ml, normal value 6.6-14 pg/ml); antithyroid autoantibodies were absent. Thyroid scintigraphy with sodium 99m Tc pertechnetate showed a small ectopic thyroid located in sublingual position, so treatment with L-thyroxine 37.5 microg/24 hr was started with rapid improvement of the clinical picture. At 17 months of age the patient developed the complete characteristic phenotype of Williams syndrome (WS); the clinical diagnosis was proven by fluorescent in situ hybridization (FISH) analysis which showed hemizygous deletion of the elastin gene on chromosome 7. Recently a case of thyroid hemiagenesis in a child with WS has been reported; our patient underscores the association of hypothyroidism and WS. Moreover, our case shows that clinical manifestations of hypothyroidism may be present and the treatment may be necessary as it is in isolated congenital hypothyroidism.

Williams-Beuren syndrome: a model of recurrent genomic mutation

Williams-Beuren syndrome is a segmental aneusomy syndrome with manifestations affecting the vascular, connective tissue, endocrine and central nervous systems. Most patients show a similar heterozygous approximately 1.5 Mb deletion at 7q11.23 that contains a number of reported genes. Deletion mapping in the few atypical patients with smaller deletions suggested that additive effects of haploinsufficiency for two or more genes might be necessary for the phenotype. Vascular stenoses are caused by haploinsufficiency at the elastin gene, while the genes responsible for the cognitive deficits are likely located at the telomeric edge of the deletion, including CYLN2 and GTF2I. Large region-specific segmental duplications predispose to misalignment and inter- or intrachromosomal unequal crossing-over causing the deletions. Atypical alleles at 7q11.23 such as inversions and deletions/insertions of large repeats, also generated through aberrant recombination between the local segmental duplications, are found in approximately 35% of transmitting parents. Genomic instability at 7q11.23 is directly related to the genomic structure of the region.

Infantile Spasms in a Patient with Williams Syndrome and Craniosynostosis

A patient with Williams syndrome, craniosynostosis, and infantile spasms is described. At age 6 months, the infant demonstrated infantile spasms and craniosynostosis and was operated on for craniosynostosis and treated with adrenocorticotropic hormone (ACTH) for the infantile spasms. ACTH completely controlled the seizures, but was halted because of the progression of ventricular hypertrophy. The seizure returned, and he was found to have elfin face, failure-to-thrive, developmental delay, and dental malformation in addition to congenital heart defects. High-resolution chromosome analysis revealed interstitial deletion of 7q11.22-q11.23. Therefore his clinical and cytogenetic diagnosis was Williams syndrome. Thyrotropin-releasing hormone (TRH) therapy reduced his seizures and improved the findings of EEG without cardiac side effects. In addition, his psychomotor development was slightly improved.

Thyroid hypoplasia of the left lobe in two girls affected by Williams syndrome

Williams syndrome is a well-recognized disorder, having an incidence of 1 in 20,000 live births. However, thyroid function in these patients is rarely studied. This paper reports thyroid hypoplasia of the left lobe in two girls affected by Williams syndrome, suggesting that it may be a feature of this syndrome.

Williams syndrome and related disorders

Three clinical conditions displaying phenotypic overlap have been linked to mutation or deletion of the elastin gene at 7q11.23. Supravalvar aortic stenosis, an autosomal dominant disorder characterized by elastin arteriopathy, is caused by mutation or intragenic deletions of ELN resulting in loss of function. Autosomal dominant cutis laxa, a primarily cutaneous condition, is the result of frameshift mutations at ELN that cause a dominant-negative effect on elastic fiber structure. Williams syndrome, a neurodevelopmental disorder is due to a 1.5 Mb deletion that includes ELN and at least 15 contiguous genes. The disorder is characterized by dysmorphic facies, mental retardation or learning difficulties, elastin arteriopathy, a unique cognitive profile of relative strength in auditory rote memory and language and extreme weakness in visuospatial constructive cognition, and a typical personality that includes overfriendliness, anxiety, and attention problems. The understanding of these disorders has progressed from phenotypic description to identification of causative mutations and insight into pathogenetic mechanisms for some aspects of the phenotype.