Idiopathic infantile hypercalcaemia--a continuing enigma

Musculoskeletal phenotypes in 3q29 deletion syndrome

3q29 deletion syndrome (3q29del) is a rare genomic disorder caused by a 1.6 Mb deletion (hg19, chr3:195725000-197350000). 3q29del is associated with neurodevelopmental and psychiatric phenotypes, including an astonishing >40-fold increased risk for schizophrenia, but medical phenotypes are less well-described. We used the online 3q29 registry of 206 individuals (3q29deletion.org) to recruit 57 individuals with 3q29del (56.14% male) and requested information about musculoskeletal phenotypes with a custom questionnaire. 85.96% of participants with 3q29del reported at least one musculoskeletal phenotype. Congenital anomalies were most common (70.18%), with pes planus (40.35%), pectus excavatum (22.81%), and pectus carinatum (5.26%) significantly elevated relative to the pediatric general population. 49.12% of participants reported fatigue after 30 min or less of activity. Bone fractures (8.77%) were significantly elevated relative to the pediatric general population. Participants commonly report receiving medical care for musculoskeletal complaints (71.93%), indicating that these phenotypes impact quality of life for individuals with 3q29del. This is the most comprehensive description of musculoskeletal phenotypes in 3q29del to date, suggests ideas for clinical evaluation, and expands our understanding of the phenotypic spectrum of this syndrome.

Musculoskeletal phenotypes in 3q29 deletion syndrome

3q29 deletion syndrome (3q29del) is a rare genomic disorder caused by a 1.6 Mb deletion (hg19, chr3:195725000â€"197350000). 3q29del is associated with neurodevelopmental and psychiatric phenotypes, including an astonishing >40-fold increased risk for schizophrenia, but medical phenotypes are less well-described. We used the online 3q29 registry ( 3q29deletion.org ) to recruit 57 individuals with 3q29del (56.14% male) and requested information about musculoskeletal phenotypes with a custom questionnaire. 85.96% of participants with 3q29del reported at least one musculoskeletal phenotype. Congenital anomalies were most common (70.18%), with pes planus (40.35%), pectus excavatum (22.81%), and pectus carinatum (5.26%) significantly elevated relative to the pediatric general population. 49.12% of participants reported fatigue after 30 minutes or less of activity. Bone fractures (8.77%) were significantly elevated relative to the pediatric general population, suggesting 3q29del impacts bone strength. Participants commonly report receiving medical care for musculoskeletal complaints (71.93%), indicating that these phenotypes impact quality of life for individuals with 3q29del. This is the most comprehensive description of musculoskeletal phenotypes in 3q29del to date, suggests ideas for clinical evaluation, and expands our understanding of the phenotypic spectrum of this syndrome.

Early outcomes of growth friendly instrumentation in children with Williams syndrome

PURPOSE

Although scoliosis and kyphosis have been associated with Williams Syndrome (WS), no previous literature has reported on surgical treatment for early onset scoliosis (EOS) in WS. The aim of this case series is to report on the outcomes of spine deformity surgery in patients with EOS and WS and any perioperative anesthetic or cardiovascular complications.

METHODS

One multicenter database was queried for all patients with WS who underwent growth-friendly (GF) treatment before age 12 between 2000 and 2017. Demographics, surgical, and growth-friendly data were queried. Radiographs were measured for curve magnitude, T1-T12 length, and T1-S1 length.

RESULTS

Seven patients were analyzed (3 males, 4 females). Patients were at a median age of 2.8 years at initial surgery with median follow-up 3.6 years (range 2.0-12 years) after index surgery. The initial surgical treatments were as follows: 2 traditional growing rods (TGR), 2 magnetically controlled growing rods (MCGR), and 3 vertical expandable prosthetic titanium ribs (VEPTR). The median duration of growth-friendly treatment was 5.0 years (range, 2.6-10.4 years) with a median number of 9 device lengthenings. The median improvement in coronal curve magnitude from preoperative to most recent follow-up was 19° (range, 54°-9°). Three patients have completed GF treatment: one underwent definitive fusion, and two are under observation with apparent spontaneous fusion and retain the original GF implants. No peri-operative anesthetic or cardiovascular complications occurred.

CONCLUSIONS

Few studies have reported on surgical outcomes in WS patients with EOS. In this case series, 6/7 patients experienced curve improvement with growth-friendly spine instrumentation. This study suggests that growth-friendly instrumentation for severe EOS in WS can be used for control of spinal deformity while allowing for further growth. Associated complications were typical of distraction-based EOS surgical treatment. There were 62 total procedures with general anesthesia, but no perioperative cardiac complications occurred.

Long-term outcome of the survivors of infantile hypercalcaemia with CYP24A1 and SLC34A1 mutations

Background

Infantile hypercalcaemia (IH) is a vitamin D₃ metabolism disorder. The molecular basis for IH is biallelic mutations in the CYP24A1 or SLC34A1 gene. These changes lead to catabolism disorders (CYP24A1 mutations) or excessive generation of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] (SLC34A1 mutations). The incidence rate of IH in children and the risk level for developing end-stage renal disease (ESRD) are still unknown. The aim of this study was to analyse the long-term outcome of adolescents and young adults who suffered from IH in infancy.

Design

Forty-two children (23 girls; average age 10.7 ± 6.3 years) and 26 adults (14 women; average age 24.2 ± 4.4 years) with a personal history of hypercalcaemia with elevated 1,25(OH)₂D₃ levels were included in the analysis. In all patients, a genetic analysis of possible IH mutations was conducted, as well as laboratory tests and renal ultrasonography.

Results

IH was confirmed in 20 studied patients (10 females). CYP24A1 mutations were found in 16 patients (8 females) and SLC34A1 in 4 patients (2 females). The long-term outcome was assessed in 18 patients with an average age of 23.8 years (age range 2–34). The average glomerular filtration rate (GFR) was 72 mL/min/1.73 m² (range 15–105). Two patients with a CYP24A1 mutation developed ESRD and underwent renal transplantation. A GFR <90 mL/min/1.73 m² was found in 14 patients (77%), whereas a GFR <60 mL/min/1.73 m² was seen in 5 patients (28%), including 2 adults after renal transplantation. Three of 18 patients still had serum calcium levels >2.6 mmol/L. A renal ultrasound revealed nephrocalcinosis in 16 of 18 (88%) patients, however, mild hypercalciuria was detected in only one subject.

Conclusions

Subjects who suffered from IH have a greater risk of progressive chronic kidney disease and nephrocalcinosis. This indicates that all survivors of IH should be closely monitored, with early implementation of preventive measures, e.g. inhibition of active metabolites of vitamin D₃ synthesis.

White matter alterations in Williams syndrome related to behavioral and motor impairments

Myelin is the electrical insulator surrounding the neuronal axon that makes up the white matter (WM) of the brain. It helps increase axonal conduction velocity (CV) by inducing saltatory conduction. Damage to the myelin sheath and WM is associated with many neurological and psychiatric disorders. Decreasing myelin deficits, and thus improving axonal conduction, has the potential to serve as a therapeutic mechanism for reducing the severity of some of these disorders. Myelin deficits have been previously linked to abnormalities in social behavior, suggesting an interplay between brain connectivity and sociability. This review focuses on Williams syndrome (WS), a genetic disorder characterized by neurocognitive characteristics and motor abnormalities, mainly known for its hypersociability characteristic. We discuss fundamental aspects of WM in WS and how its alterations can affect motor abilities and social behavior. Overall, findings regarding changes in myelin genes and alterations in WM structure in WS suggest new targets for drug therapy aimed at improving conduction properties and altering brain-activity synchronization in this disorder.

Health Care Supervision for Children With Williams Syndrome

This set of recommendations is designed to assist the pediatrician in caring for children with Williams syndrome (WS) who were diagnosed by using clinical features and with chromosome 7 microdeletion confirmed by fluorescence in situ hybridization, chromosome microarray, or multiplex ligation-dependent probe amplification. The recommendations in this report reflect review of the current literature, including previously peer-reviewed and published management suggestions for WS, as well as the consensus of physicians and psychologists with expertise in the care of individuals with WS. These general recommendations for the syndrome do not replace individualized medical assessment and treatment.

Endocrine manifestations in children with Williams-Beuren syndrome

AIM

Endocrine abnormalities in Williams-Beuren syndrome (WBS) include growth retardation, precocious puberty, hypercalcaemia and thyroid disorders. We aimed to characterise these abnormalities in a national cohort of children with WBS.

METHODS

A retrospective study comprising a national cohort of individuals with WBS in Israel (16 males, 18 females) followed between 2010 and 2016.

RESULTS

The age at diagnosis of WBS was 1.4 ± 1.0 years. Height standard deviation score (SDS) at last visit was correlated with the midparental height SDS (r = 0.46 p = 0.007). Yet, participants did not reach their midparental height, with a difference of 1.40 ± 0.85SD (p < 0.001). Short stature below the 3rd percentile was found in 14 participants (41%). Mean insulin-like growth factor 1 SDS was low (-0.61 ± 1.64) and was correlated with the mean height SDS (r = 0.63 p = 0.038). Two participants were diagnosed with growth hormone deficiency, and initiation of growth hormone treatment improved their height velocity. A total of eight participants (23.5%) had mild hypercalcaemia, five girls (14.7%) had precocious puberty and five participants (14.7%) had thyroid abnormalities.

CONCLUSION

Individuals with WBS had a distinct growth pattern consisting of growth restriction at all ages, resulting in final adult height in the low-normal range. Precocious puberty, hypercalcaemia and thyroid abnormalities should be screened for and treated as needed.

A Pediatric Patient with a CYP24A1 Mutation: Four Years of Clinical, Biochemical, and Imaging Follow-Up

BACKGROUND

A female infant was admitted to hospital due to failure to thrive. She presented hypercalcemia (4.09 mmol/L, normal range: 2.2-2.65 mmol/L), high 25-hydroxyvitamin D (283 nmol/L, normal range: 75-250 nmol/L), 1,25-dihydroxyvitamin D in the upper normal range, and low parathyroid hormone. Vitamin D intoxication was suspected. The patient had received routine rickets prophylaxis.

METHODS

Williams-Beuren syndrome was genetically excluded. Sequencing of CYP24A1 showed 2 mutations: c.443T>C and c.1186C>T.

RESULTS

The patient's clinical status improved after intravenous rehydration, cessation of supplementation, and on a low-calcium diet. 25-Hydroxyvitamin D concentrations normalized within days, while 1,25-dihydroxyvitamin D remained in the upper normal range. We also investigated our patient's bone health.

CONCLUSION

The patient was hospitalized initially on suspicion of vitamin D intoxication but proved to be a case of compound heterozygosity. Data on the long-term clinical and biochemical evolution of patients with idiopathic infantile hypercalcemia are sparse. Our follow-up showed seasonal variations of vitamin D and calcium parameters, with no influence on kidney function or bone health for the investigated period.

Hypercalcemia in Patients with Williams-Beuren Syndrome

OBJECTIVE

To evaluate the timing, trajectory, and implications of hypercalcemia in Williams-Beuren syndrome (WBS) through a multicenter retrospective study.

STUDY DESIGN

Data on plasma calcium levels from 232 subjects with WBS aged 0-67.1 years were compared with that in controls and also with available normative data. Association testing was used to identify relevant comorbidities.

RESULTS

On average, individuals with WBS had higher plasma calcium levels than controls, but 86.7% of values were normal. Nonpediatric laboratories overreport hypercalcemia in small children. When pediatric reference intervals were applied, the occurrence of hypercalcemia dropped by 51% in infants and by 38% in toddlers. Across all ages, 6.1% of the subjects had actionable hypercalcemia. In children, actionable hypercalcemia was seen in those aged 5-25 months. In older individuals, actionable hypercalcemia was often secondary to another disease process. Evidence of dehydration, hypercalciuria, and nephrocalcinosis were common in both groups. Future hypercalcemia could not be reliably predicted by screening calcium levels. A subgroup analysis of 91 subjects found no associations between hypercalcemia and cardiovascular disease, gastrointestinal complaints, or renal anomalies. Analyses of electrogradiography data showed an inverse correlation of calcium concentration with corrected QT interval, but no acute life-threatening events were reported.

CONCLUSIONS

Actionable hypercalcemia in patients with WBS occurs infrequently. Although irritability and lethargy were commonly reported, no mortality or acute life-threatening events were associated with hypercalcemia and the only statistically associated morbidities were dehydration, hypercalciuria, and nephrocalcinosis.

Genome wide array-CGH and qPCR analysis for the identification of genome defects in Williams' syndrome patients in Saudi Arabia

Background

Williams-Beuren Syndrome (WBS) is a rare neurodevelopmental disorder characterized by dysmorphic features, cardiovascular defects, cognitive deficits and developmental delay. WBS is caused by a segmental aneuploidy of chromosome 7 due to heterozygous deletion of contiguous genes at the long arm of chromosome 7q11.23. We aimed to apply array-CGH technique for the detection of copy number variants in suspected WBS patients and to determine the size of the deleted segment at chromosome 7q11.23 in correlation with the phenotype. The study included 24 patients referred to the CEGMR with the provisional diagnosis of WBS and 8 parents. The patients were subjected to conventional Cytogenetic (G-banding) analysis, Molecular Cytogenetic (Fluorescent In-Situ Hybridization), array-based Comparative Genomic Hybridization (array-CGH) and quantitative Real time PCR (qPCR) Techniques.

Results

No deletions were detected by Karyotyping, however, one patient showed unbalanced translocation between chromosome 18 and 19, the karyotype was 45,XX, der(19) t(18;19)(q11.1;p13.3)-18. FISH technique could detect microdeletion in chromosome 7q11.23 in 10/24 patients. Array-CGH and qPCR confirmed the deletion in all samples, and could detect duplication of 7q11.23 in three patients and two parents. Furthermore, the size of the deletion could be detected accurately by both array-CGH and qPCR techniques. Three patients not showing the 7q11.23 deletion were diagnosed by array-CGH to have deletion in chr9p13.1-p11.2, chr18p11.32-p11.21 and chr1p36.13.

Conclusion

Both FISH and array-CGH are reliable methods for the diagnosis of WBS; however, array-CGH has the advantage of detection of genome deletions/ duplications that cannot otherwise be detected by conventional cytogenetic techniques. Array-CGH and qPCR are useful for detection of deletion sizes and prediction of the interrupted genes and their impact on the disease phenotype. Further investigations are needed for studying the impact of deletion sizes and function of the deleted genes on chromosome 7q11.23.

Trial registration

ISRCTN ISRCTN73824458. MOCY-D-16-00041R1. Registered 28 September 2014. Retrospectively registered.

Description of common musculoskeletal findings in Williams Syndrome and implications for therapies

Williams syndrome (WS), also referred to as Williams-Beuren syndrome (WBS), is a relatively rare genetic disorder affecting ∼1/10,000 persons. Since the disorder is caused by a micro-deletion of ∼1.5 Mb, it is not surprising that the manifestations of WS are extremely broad, involving most body systems. In this paper, we primarily focus on the musculoskeletal aspects of WS as these findings have not been the subject of a comprehensive review. We review the MSK features commonly seen in individuals with WS, along with related sensory and neurological issues interacting with and compounding underlying MSK abnormalities. We end by providing perspective, particularly from the vantage point of a physical therapist, on therapeutic interventions to address the most common MSK and related features seen in WS. Clin. Anat. 29:578-589, 2016. © 2016 Wiley Periodicals, Inc.

Calcium and bone homeostasis in heterozygous carriers of CYP24A1 mutations: A cross-sectional study

BACKGROUND

Bi-allelic CYP24A1 mutations can cause idiopathic infantile hypercalcemia (IIH), adult-onset nephrocalcinosis, and possibly bone metabolism disturbances. It is currently unclear if heterozygous carriers experience clinical problems or biochemical abnormalities. Our objective is to gain insight in the biochemical profile and health problems in CYP24A1 heterozygotes.

STUDY DESIGN

Cross-sectional evaluation of participants. Data of previously reported carriers are reviewed.

SETTING AND PARTICIPANTS

Outpatient clinic of a tertiary care hospital. Participants were eight family members of an infant with a well-characterized homozygous CYP24A1 mutation c.1186C>T p.(Arg396Trp).

OUTCOMES

Serum vitamin D metabolites. Symptoms or biochemical signs of hypercalcemia, hypercalciuria or nephrocalcinosis. Bone health in heterozygous as compared to wild type (WT) subjects.

MEASUREMENTS

Genotyping by Sanger sequencing; vitamin D metabolites by liquid chromatography tandem mass spectrometry; renal, calcium and bone markers by biochemical analyses; presence of nephrocalcinosis by renal ultrasound; bone health by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography.

RESULTS

Six participants were heterozygous carriers of the mutation. None of the heterozygous subjects had experienced IIH. One had a documented history of nephrolithiasis, two others had complaints compatible with this diagnosis. No major differences between WT and heterozygous subjects were found regarding bone health, serum or urinary calcium or 25OHD/24,25(OH)2D ratio. Literature reports on three out of 33 heterozygous cases suffering from IIH. In all three, the 25OHD/24,25(OH)2D ratio was highly elevated. Nephrocalcinosis was frequently reported in family members of IIH cases.

LIMITATIONS

Small sample size, lack of a large control group.

CONCLUSIONS

Our and literature data suggest that most heterozygous CYP24A1 mutation carriers have a normal 25OHD/24,25(OH)2D ratio, are usually asymptomatic and have a normal skeletal status but may possibly be at increased risk of nephrocalcinosis. A review of the available literature suggests that an elevated 25OHD/24,25(OH)2D ratio may be associated with symptoms of IHH, irrespective of carrier status.

Prevalence of scoliosis in Williams-Beuren syndrome patients treated at a regional reference center

OBJECTIVE

This study assessed the prevalence of scoliosis and the patterns of scoliotic curves in patients with Williams-Beuren syndrome. Williams-Beuren syndrome is caused by a chromosome 7q11.23 deletion in a region containing 28 genes, with the gene encoding elastin situated approximately at the midpoint of the deletion. Mutation of the elastin gene leads to phenotypic changes in patients, including neurodevelopmental impairment of varying degrees, characteristic facies, cardiovascular abnormalities, hypercalcemia, urological dysfunctions, and bone and joint dysfunctions.

METHODS

A total of 41 patients diagnosed with Williams-Beuren syndrome, who were followed up at the genetics ambulatory center of a large referral hospital, were included in the study. There were 25 male subjects. The patients were examined and submitted to radiographic investigation for Cobb angle calculation.

RESULTS

It was observed that 14 patients had scoliosis; of these 14 patients, 10 were male. The pattern of deformity in younger patients was that of flexible and simple curves, although adults presented with double and triple curves. Statistical analysis showed no relationships between scoliosis and age or sex.

CONCLUSION

This study revealed a prevalence of scoliosis in patients with Williams-Beuren syndrome of 34.1%; however, age and sex were not significantly associated with scoliosis or with the severity of the curves.

Environmental sound recognition by timbre in children with Williams syndrome

Anecdotal reports have described children with Williams syndrome (WS) as presenting outstanding skills for recognizing environmental sounds by their timbre. This has led to suggest that the skills for environmental sound recognition by timbre are highly developed in WS. Furthermore, the term hypertimbria has been proposed to refer to this feature. However, no academic research has assessed these skills in WS. This study therefore aimed to contrast the reports on the highly developed skills for environmental sound recognition by timbre in children with WS. An environmental sound recognition task was administered to children with WS, children with Down syndrome of the same chronological age and cognitive level, and chronological age-matched typically developing children. Participants with WS performed significantly lower than their typically developing peers and no significant differences were found between the WS and Down syndrome groups. Unlike previous reports, this study points out that in WS environmental sound recognition by timbre does not constitute a phenotypic strength either in absolute or relative terms. Results suggest that children with WS do not present hypertimbria or preserved skills for timbre recognition. We discuss the implications of these results for theories of cognitive modularity.

Cytochrome P450-mediated metabolism of vitamin D

The vitamin D signal transduction system involves a series of cytochrome P450-containing sterol hydroxylases to generate and degrade the active hormone, 1α,25-dihydroxyvitamin D3, which serves as a ligand for the vitamin D receptor-mediated transcriptional gene expression described in companion articles in this review series. This review updates our current knowledge of the specific anabolic cytochrome P450s involved in 25- and 1α-hydroxylation, as well as the catabolic cytochrome P450 involved in 24- and 23-hydroxylation steps, which are believed to initiate inactivation of the vitamin D molecule. We focus on the biochemical properties of these enzymes; key residues in their active sites derived from crystal structures and mutagenesis studies; the physiological roles of these enzymes as determined by animal knockout studies and human genetic diseases; and the regulation of these different cytochrome P450s by extracellular ions and peptide modulators. We highlight the importance of these cytochrome P450s in the pathogenesis of kidney disease, metabolic bone disease, and hyperproliferative diseases, such as psoriasis and cancer; as well as explore potential future developments in the field.

How much vitamin D for children?

Recently a number of studies have reported worldwide recrudescence of biochemical and clinical rickets, despite continuous revisions of the experts about the adequate intake of vitamin D for infants and children to maintain an adequate 25-hydroxyvitamin D status and assure the achievement of peak bone mass during the growth. The aim of this review is to illustrate the current opinions and controversies about what should be considered the normal range for serum 25-hydroxyvitamin D concentrations and which doses of vitamin D supplements should be recommended in the various pediatric ages and in different contests as climatic regions, colour of skin and sunlight exposure.

Psychopathological and behavior impairments in Williams-Beuren syndrome: the influence of gender, chronological age, and cognition

The aim of this study was to explore psychopathological and behavior impairments in Williams-Beuren syndrome (WBS) by focusing on individual differences rather than group tendencies. Parent/Guardian ratings on the Child Behavior Checklist were analyzed in order to examine the influence of gender, chronological age, and cognitive abilities on psychopathological impairment within WBS. In line with predictions, and consistent with cognitive heterogeneity in WBS, psychopathological and behavioral abnormalities were variable, with gender and specific cognitive abilities making significant and independent contributions to this variance. For gender, females were significantly more likely than males with WBS to display difficulties with externalizing problems. For specific cognitive abilities, those cognitive functions characteristic of the classic WBS cognitive profile (a strength in verbal skills and a weakness in spatial skills) related to significantly greater internalizing difficulties. Future studies should explore underlying genetic and neurological differences in individuals with WBS in order to help explain the variability in psychopathological and cognitive functions.

25-Hydroxyvitamin D-24-hydroxylase (CYP24A1): its important role in the degradation of vitamin D

CYP24A1 is the cytochrome P450 component of the 25-hydroxyvitamin D(3)-24-hydroxylase enzyme that catalyzes the conversion of 25-hydroxyvitamin D(3) (25-OH-D(3)) and 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) into 24-hydroxylated products, which constitute the degradation of the vitamin D molecule. This review focuses on recent data in the CYP24A1 field, including biochemical, physiological and clinical developments. Notable among these are: the first crystal structure for rat CYP24A1; mutagenesis studies which change the regioselectivity of the enzyme; and the finding that natural inactivating mutations of CYP24A1 cause the genetic disease idiopathic infantile hypercalcemia (IIH). The review also discusses the emerging correlation between rising serum phosphate/FGF-23 levels and increased CYP24A1 expression in chronic kidney disease, which in turn underlies accelerated degradation of both serum 25-OH-D(3) and 1,25-(OH)(2)D(3) in this condition. This review concludes by evaluating the potential clinical utility of blocking this enzyme with CYP24A1 inhibitors in various disease states.

Detection of deletions at 7q11.23 in Williams-Beuren syndrome by polymorphic markers

INTRODUCTION

Williams-Beuren syndrome (WBS; OMIM 194050) is caused by a hemizygous contiguous gene microdeletion at 7q11.23. Supravalvular aortic stenosis, mental retardation, overfriendliness, and ocular and renal abnormalities comprise typical symptoms in WBS. Although fluorescence in situ hybridization is widely used for diagnostic confirmation, microsatellite DNA markers are considered highly informative and easily manageable.

OBJECTIVES

This study aimed to test the microsatellite markers for the diagnosis of Williams-Beuren syndrome, to determine the size and parental origin of microdeletion, compare the clinical characteristics between patients with different sizes of the deletion and parental origin.

METHODS

We studied 97 patients with clinical diagnosis of Williams-Beuren syndrome using five microsatellite markers: D7S1870, D7S489, D7S613, D7S2476 and D7S489_A.

RESULTS AND DISCUSSION

Using five markers together, the result was informative in all patients. The most informative marker was D7S1870 (78.4%), followed by D7S613 (75.3%), D7S489 (70.1%) and D7S2476 (62.9%). The microdeletion was present in 84 (86.6%) patients and absent in 13 (13.4%) patients. Maternal deletions were found in 52.4% of patients and paternal deletions in 47.6% of patients. The observed size of deletions was 1.55 Mb in 76/ 84 patients (90.5%) and 1.84 Mb in 8/84 patients (9.5%). SVAS as well as ocular and urinary abnormalities were more frequent in the patients with a deletion. There were no clinical differences in relation to either the size or parental origin of the deletion.

CONCLUSION

Using these five selected microsatellite markers was informative in all patients, thus can be considered an alternative method for molecular diagnosis in Williams-Beuren syndrome.

Involvement of claudin 3 and claudin 4 in idiopathic infantile hypercalcaemia: a novel hypothesis?

BACKGROUND

Idiopathic infantile hypercalcaemia (IIH) is a rare disease that generally resolves spontaneously between the age of 1 and 3 years. Similar symptoms may occur in patients suffering from Williams-Beuren syndrome (WBS), which is caused by a microdeletion on chromosome 7. Two of the genes, named CLDN3 and CLDN4, located within this region are members of the claudin family that has been shown to be involved in paracellular calcium (Ca(2+)) absorption. Based on the hemizygous loss of CLDN3 and CLDN4 in WBS and the function of these genes in paracellular Ca(2+) transport, we hypothesized that mutations in CLDN3 or CLDN4 could also be involved in IIH.

METHODS

Biochemical characteristics, including calciotropic hormone levels, were obtained from three typical IIH patients. CLDN3 and CLDN4 sequences were also analysed in these patients. The major intestinal Ca(2+) transporter TRPV6 was also screened for the presence of mutations, since hypercalcaemia in IIH and WBS has been shown to result from intestinal hyperabsorption. All three patients were also analysed for the presence of deletions or duplications using a single-nucleotide polymorphism (SNP) array for genomic DNA.

RESULTS

The serum Ca(2+) levels of patients were 2.9, 3.3 and 3.8 mmol/L (normal <2.7 mmol/L). Levels of 25-hydroxyvitamin D(3) and 1,25-dihydroxyvitamin D(3) were normal, parathyroid hormone (PTH) and PTH-related peptide (PTHrP) levels were appropriately low. Sequencing of coding regions and intron-exon boundaries did not reveal mutations in CLDN3, CLDN4 and TRPV6. Identified SNPs were not correlated with the disease phenotype. A SNP array did not reveal genomic deletions or duplications.

CONCLUSIONS

Biochemical analysis did not reveal inappropriate levels of calciotropic hormones in IIH patients in this study. Furthermore, based on the lack of mutations in CLDN3, CLDN4 and TRPV6, we conclude that IIH is neither caused by mutations in these candidate genes nor by deletions or duplications in the genome of these patients.

Social approach in pre-school children with Williams syndrome: the role of the face

BACKGROUND

Indiscriminate social approach behaviour is a salient aspect of the Williams syndrome (WS) behavioural phenotype. The present study examines approach behaviour in pre-schoolers with WS and evaluates the role of the face in WS social approach behaviour.

METHOD

Ten pre-schoolers with WS (aged 3-6 years) and two groups of typically developing children, matched to the WS group on chronological or mental age, participated in an observed play session. The play session incorporated social and non-social components including two components that assessed approach behaviour towards strangers; one in which the stranger's face could be seen and one in which the stranger's face was covered.

RESULTS

In response to the non-social aspects of the play session, the WS group behaved similarly to both control groups. In contrast, the pre-schoolers with WS were significantly more willing than either control group to engage with a stranger, even when the stranger's face could not be seen.

CONCLUSION

The findings challenge the hypothesis that an unusual attraction to the face directly motivates social approach behaviour in individuals with WS.

Beyond behaviour: is social anxiety low in Williams syndrome?

Individuals with Williams syndrome (WS) exhibit striking social behaviour that may be indicative of abnormally low social anxiety. The present research aimed to determine whether social anxiety is unusually low in WS and to replicate previous findings of increased generalised anxiety in WS using both parent and self report. Fifteen individuals with WS aged 12-28 years completed the Spence Children's Anxiety Scale (SCAS) and the Children's Automatic Thoughts Scale (CATS). Their responses were compared to clinically anxious and community comparison groups matched on mental age. The findings suggest that WS is not associated with unusually low social anxiety but that generalised anxiety symptoms and physical threat thoughts are increased in WS, relative to typically developing children.

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.

Transitional implants in a patient with Williams-Beuren syndrome: a four-year follow-up

Williams-Beuren syndrome (WBS) is characterized by several diagnostic features, including oligodontia. Restoration of congenitally missing teeth in patients with WBS is a challenge, both emotionally and clinically. In the atrophied alveolar bone process of a juvenile patient with WBS, the maxillary lateral incisors were replaced with two Immediate Provisional Implants (IPI). Early implant loading was used with temporary acrylic resin crowns that were replaced by semi-permanent restorations; the case has been followed for four years. Restoration of the missing maxillary lateral incisors with IPIs and temporary crowns proved to be a convenient, long-lasting and psychologically acceptable solution to the patient and her family.

Long-term follow-up of patients with idiopathic infantile hypercalcaemia

Idiopathic infantile hypercalcaemia (IIH) is a rare disorder of unknown etiology that presents with hypercalcaemia in a child's first year of life. There is only a limited number of published reports of the natural history of this condition, and the long-term prognosis is largely unknown. The presentation, treatment and long-term follow-up of 11 children with IIH treated at our institution since 1993 are described. Hypercalcaemia resolved in the majority of children by the time they were 3 years of age, but nephrocalcinosis and persistent hypercalciuria were common, and, in some cases, urinary calcium excretion increased after initially becoming normal. This study suggests that clinical and biochemical abnormalities may persist for longer than previously reported and implies the need for ongoing surveillance of patients with IIH.

Hypothesis for development of a behavioral phenotype in Williams syndrome

We investigated the natural history of Williams syndrome (WS), including physical characteristics and cognitive, academic language, sensory integration, and adaptive and maladaptive behavior in 32 patients (age 3 to 30 years). These patients were available for psychoeducational testing, parent interview, medical and educational record review, and behavioral observation. Thirty-seven nonlocal individuals (age 8 months to 31 years) were not tested but data on history and development, sensory integration, adaptive and maladaptive behavior were collected resulting in a total sample of 69. The unique constellation of physical manifestations and associated clinical problems in WS contributes to a characteristic behavioral phenotype of 6 factors beginning in infancy with development of salient attachment behaviors. Later a key issue affecting the learning abilities of both the school-aged child and adult with WS was an inadequate development in the use of tools. Theoretical constructs from developmental behavioral genetics, attachment theory, operant conditioning, neuropsychology, and psychosocial theory considered interactively offer explanations for these characteristics.

Adults with Williams syndrome

Reports of adults with Williams syndrome (WS) have been rare. We have evaluated 13 adult WS patients and reviewed 16 case reports of WS in patients older than age 16 years. Adults in our study had progressive multisystem medical problems. Cardiovascular complications were common (12/13) including hypertension (8), supravalvular aortic stenosis (9), aortic hypoplasia (3), pulmonic artery stenosis (4), peripheral stenoses (3), and mitral valve prolapse (2). Joint limitation (12/13) was progressive, often accompanied by kyphoscoliosis and lordosis. Recurrent urinary tract infections in 6 individuals led to radiologic studies showing urethral stenosis in 2, and bladder diverticula and vesicoureteral reflux in 3. Gastrointestinal problems included obesity (5), chronic constipation (7), diverticulosis (3), and cholelithiasis (4). Hypercalcemia was documented in 5 patients, although others had hypercalcemic symptoms (abdominal pain, polyuria, and constipation). One 45-year-old man had parathyroid hyperplasia. Previous reports likewise document significant morbidity. Thus, Williams syndrome in an adult appears to dictate aggressive evaluation and monitoring. Investigation of calcium metabolism should be undertaken in each adult WS patient.

Aversion, awareness, and attraction: investigating claims of hyperacusis in the Williams syndrome phenotype

BACKGROUND

Williams syndrome (WS), a neurodevelopmental disorder, is characterized by pervasive cognitive deficits alongside a relative sparing of auditory perception and cognition. A frequent characteristic of the phenotype is adverse reactions to, and/or fascination with, certain sounds. Previously published reports indicate that people with WS experience hyperacusis, yet careful examination reveals that the term 'hyperacusis' has been used indiscriminately in the literature to describe quite different auditory abnormalities.

METHOD

In an effort to clarify and document the incidence of auditory abnormalities in and among people with WS we collected data from parents of people with WS (n = 118) and comparison groups of people with Down syndrome, autism, and normal controls.

RESULTS

Our findings revealed four phenomenologically separate auditory abnormalities, all of which were significantly more prevalent in WS than the three comparison groups. Among people with WS, we found relatively few reports of true hyperacusis (lowered threshold for soft sounds) or auditory fascinations/fixations, whereas 80% reported fearfulness to idiosyncratically particular sounds, and 91% reported lowered uncomfortable loudness levels, or 'odynacusis.'

CONCLUSIONS

Our results confirm anecdotal reports of an unusual auditory phenotype in WS, and provide an important foundation for understanding the nature of auditory experience and pathology in WS. We conclude by reviewing the ways in which the present findings extend and complement recent neuroanatomical and neurophysiological findings on auditory function in people with WS.

Renal and urinary findings in 20 patients with Williams-Beuren syndrome diagnosed by fluorescence in situ hybridization (FISH)

PURPOSE: Williams-Beuren syndrome is a rare multiple anomalies/mental retardation syndrome caused by deletion of contiguous genes at chromosome region 7q11.23. The aim of this work was to determine the frequency and the types of renal and urinary tract anomalies in 20 patients with Williams-Beuren syndrome. METHODS: The fluorescence in situ hybridization test using a LSI Williams syndrome region DNA probe was performed for all 20 patients to confirm the diagnosis of Williams-Beuren syndrome. A prospective study was performed in order to investigate renal and urinary aspects using laboratory assays to check renal function, ultrasonography of the kidneys and urinary tract, voiding cystourethrogram and urodynamics. RESULTS: Deletion of the elastin gene (positive fluorescence in situ hybridization test) was found in 17 out of 20 patients. Renal alterations were diagnosed in 5 of 17 (29%) the patients with the deletion and in 1 of 3 patients without the deletion. Fourteen patients with the deletion presented dysfunctional voiding. Arterial hypertension was diagnosed in 3 patients with deletions and 1 of these presented bilateral stenosis of the renal arteries. CONCLUSIONS: Due to the high incidence of renal and urinary abnormalities in Williams-Beuren syndrome, performing a systematic laboratory and sonographic evaluation of the patients is recommended.

Further delineation of the behavioral and neurologic features in Costello syndrome

To describe clinical and neurodevelopmental phenotypes of Costello syndrome, we performed a retrospective review of the clinical records and findings in 10 children with Costello syndrome. All patients showed significant postnatal growth retardation and severe feeding difficulties leading to failure to thrive from early infancy. All required tube feeding and some needed high-calorie formulas for variable periods. Developmental quotients/IQs in seven children were 50 or less, and three were in the mildly retarded range. Five had seizures. Remarkable manifestations not previously reported were the characteristic behavior in infancy. Although happy and sociable personality was always emphasized in the genetic literature, all children showed significant irritability, including hypersensitivity to sound and tactile stimuli, sleep disturbance, and excess shyness with strangers in infancy. Those symptoms usually disappeared around age 2-4 years. Other clinical signs included cardiac abnormalities (8), musculoskeletal abnormalities (10), ophthalmological manifestations (5), increased urinary vanillymandelic acid (VMA) and homovanillic acid (HVA) (3), rhabdomyosarcoma (1), laryngomalacia (1), and cryptorchidism (1). Only three girls had papillomata. Family histories were negative for Costello syndrome. In conclusion, we confirm the wide spectrum of mental function in patients with Costello syndrome, which ranges from severe to mild. During infancy Costello syndrome showed remarkable irritability with severe feeding problems, which attributes significant difficulties to the parents of affected children.

Child clinical/pediatric neuropsychology: some recent advances

The neuropsychological assets and deficits of several types of pediatric neurological disease, disorder, and dysfunction are described. These are examined from the perspective of the syndrome of nonverbal learning disabilities (NLD) and the "white matter model" designed to explain its complex manifestations. It is concluded that children with some of these diseases exhibit the NLD phenotype, whereas others do not. For the most part, the diseases in which the NLD phenotype is particularly evident are those wherein it has been demonstrated that perturbations of white matter (long myelinated fibers) are particularly prominent.

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.

Mütterliche Belastung bei Kindern mit Williams-Beuren-Syndrom, Down-Syndrom, geistiger Behinderung nichtsyndromaler Ätiologie im Vergleich zu der nichtbehinderter Kinder

Zusammenfassung: Fragestellung: In der vorliegenden Studie sollte geklärt werden, ob sich Mütter von Kindern mit geistiger Behinderung unterschiedlicher Ätiologie (Williams-Beuren-Syndrom - WBS, Down-Syndrom - DS, nichtsyndromaler Ätiologie - LB/GB) von Müttern nichtbehinderter Kinder in ihrem Belastungserleben unterscheiden. Methodik: Es wurden 85 Mütter von Kindern mit WBS, DS, LB/GB und Mütter von nichtbehinderten Kindern (VG) mithilfe des Patenting Stress Indexes (PSI) befragt. Den Müttern wurde zusätzlich die Child Behavior Checklist (CBCL) vorgelegt, um kindliche Verhaltensauffälligkeiten zu erfassen. Die Parallelisierung fand anhand desAlters der Kinder, des Geschlechts und der Wortschatztestleistung im Hamburg Wechsler Intelligenztest (HAWIK-R) statt. Ergebnisse: Mütter von Kindern mit WBS und DS weisen einen signifikanten höheren PSI-Gesamtstresswert auf als Mütter von Kindern mit LB/GB und VG. Dieses Ergebnis ist auf signifikante Unterschiede zwischen den Gruppen bezüglich des kindbezogenen Stresses, aber nicht der elternbezogenen Belastung, zurückzuführen. Auf Subskalenebene des Kinderbereichs fühlen sich Mütter von Kindern mit WBS und DS im Vergleich zu den anderen beiden Gruppen signifikant durch die kindlichen Anforderungen und dem wenig akzeptablen Verhalten ihres Kindes belastet. Mütter von Kindern mit LB/GB beschreiben sich ebenfalls als signifikant belasteter durch ein unakzeptables kindliches Verhalten als Mütter normalentwickelter Kinder. Mütter von Kindern mit WBS schätzen ihre Belastung durch ein hyperaktives Verhalten, eine geringe Anpassungsfähigkeit und größere Stimmungslabilität ihrer Kinder signifikant höher ein als Mütter der anderen drei Gruppen. Bezüglich des Erwachsenenbereichs schätzen sich Mütter von Kindern mit DS als signifikant depressiver und weniger kompetent in ihrem Erziehungsverhalten ein und geben mehr Gesundheitssorgen an als Mütter der anderen drei Gruppen. Mütter von Kindern mit LB/GB fühlen sich im Vergleich zu den anderen Gruppen am wenigsten durch partnerschaftliche Probleme belastet und in ihrer elterlichen Rolle eingeschränkt. Kein Zusammenhang kann zwischen dem kindlichen Alter, dem sozioökonomischen Status und dem Belastungsgrad gesehen werden, allerdings korrelieren der Grad der geistigen Behinderung als auch der Verhaltensauffälligkeiten signifikant mit dem mütterlichen Belastungsgrad. Schlussfolgerung: Es kann festgehalten werden, dass es sowohl allgemeine Belastungsfaktoren wie die hohen Anforderungen durch das Kind und sein unakzeptableres Verhalten gibt, die mit einer kindlichen Behinderung einhergehen als auch spezifische, die mit dem Verhaltensphänotyp eines Syndroms assoziiert sind.

Language in mental retardation: Individual and syndromic differences, and neurogenetic variation 1Based on a keynote presentation at the Third European Conference on Psychological Theory and Research in Mental Retardation, Geneva, September 1st, 2000

Predominantly non-etiological conceptions have dominated the field of mental retardation (MR) since the discovery of the genetic etiology of Down syndrome (DS) in the sixties. However, contemporary approaches are becoming more etiologically oriented. Important differences across MR syndromes of genetic origin are being documented, particularly in the cognition and language domains, differences not explicable in terms of psychometric level, motivation, or other dimensions. This paper highlights the major difficulties observed in the oral language development of individuals with genetic syndromes of mental retardation. The extent of inter- and within-syndrome variability are evaluated. Possible brain underpinnings of the behavioural differences are envisaged. Cases of atypically favourable language development in MR individuals are also summarized and explanatory variables discussed. It is suggested that differences in brain architectures, originating in neurological development and having genetic origins, may largely explain the syndromic as well as the individual within-syndrome variability documented. Lastly, the major implications of the above points for current debates about modularity and developmental connectionism are spelt out.

Procedural learning deficit in children with Williams syndrome

The present study was aimed at evaluating implicit memory processes in subjects with Williams syndrome (WS) and comparing them to mental-age (MA) matched normal children. For this purpose, tests of verbal and visuo-perceptual explicit memory, verbal and visual repetition priming as well as procedural learning tasks were administered to 12 WS and 12 MA matched subjects. WS subjects showed a level of repetition priming similar to that of MA normal controls. In contrast, WS children showed a reduced learning rate in the two procedural tasks. Although deficient explicit memory and executive dysfunction cannot be excluded from the performance of WS subjects, these results suggest a specific deficit of procedural learning in this particular group of mentally retarded children. This finding is relevant for our knowledge about the qualitative aspects of the anomalous cognitive development in mentally retarded people and the neurobiological substrate underlying this development.

Familial Williams-Beuren syndrome showing varying clinical expression

Williams-Beuren syndrome (WBS) is a contiguous gene syndrome that occurs mainly sporadically, with an estimated frequency of 1:13,700 to 1:25,000 [Grimm and Wesselhoeft, 1980; Martin et al., 1984; Udwin, 1990]. The cases of monozygotic twins concordant for WBS and dizygotic twins discordant for the syndrome have been reported. In addition, a few familial cases have been described since 1993. The clinical diagnosis has been supported by molecular genetic findings in only two patients, however. We herein report on two families in which the WBS was inherited in girls from their mothers. All four patients showed the typical hemizygous deletion at 7q11.23 [46,XX, ish,del(7)(q11.23q11.23) (ELN/LIMK1/D7S-613x1, D7S486/D7S522x2)], but the clinical picture was strikingly variable within and between families.

The middle aortic syndrome: an important feature of Williams' syndrome

The middle aortic syndrome, with diffuse narrowing of the thoracic and abdominal aorta, was present in 10 of 18 patients with Williams' syndrome (55%). There were 3 thoracic coarctations, and 2 abdominal coarctations, with gradients greater than 20 mmHg across the zone of narrowing. Seven patients had mild renal arterial stenosis, and 6 had visceral arterial stenoses. Ten were hypertensive. Measured dimensions of the aortic lumen failed to increase with age in 3 males who had serial angiographic studies. One developed mesenteric arterial stenosis, with mild bilateral renal arterial stenoses, between the ages of 9 and 19 years. Aortic intravascular ultrasound performed in 2 patients confirmed abnormally thick vessel walls with small lumens. Diffusely narrowed and thick-walled stiff arteries, lacking elastin, are a feature of Williams' syndrome. The arteriopathy tends to progress with age, and systemic hypertension is common in teenagers and beyond. The middle aortic syndrome was present in more than half our patients, and does not necessarily reflect a bias because of cardiologic referral. Aortography with measurement of aortic diameters and delineation of the visceral branches is an important requirement for complete evaluation of patients with Williams' syndrome.

Elevated ambulatory blood pressure in 20 subjects with Williams syndrome

Previous studies report conflicting frequencies of hypertension in cohorts of patients with Williams syndrome (WS). We studied blood pressure (BP) in WS using 24-hour ambulatory BP monitoring. This technique reliably measures day- and nighttime BP in a subject's natural environment and provides better prognostic information on long-term risks of hypertension than casual BP determinations. Twenty WS subjects evaluated through a multidisciplinary WS clinic and 35 age and gender-matched controls were studied. We found that WS subjects had significantly higher ambulatory BP than controls. After controlling for age, sex, and weight, the diagnosis of WS added approximately 10 mmHg to mean daytime and nighttime BPs. Hypertension, as defined by elevated mean daytime BP, was present in 40% of WS subjects versus 14% of controls (P < 0.05); among the children studied this difference was even more dramatic with 46% of WS children versus 6% of control children classified as hypertensive (P = 0.01). We also demonstrated normal diurnal BP variation but no evidence of a "white coat" effect or increased BP variability. Interestingly, parental reporting of a history of infantile hypercalcemia was strongly associated with the presence of hypertension (P = 0.008). Our data demonstrate that both children and adults with WS have higher mean BP and higher frequency of hypertension than healthy controls. Thus, elevated BP readings in the office setting should not be dismissed but require more thorough assessment.

Williams-Beuren syndrome: an update and review for the primary physician

Williams-Beuren syndrome is an autosomal dominant disorder resulting from a submicroscopic deletion of contiguous genes on the long arm of chromosome 7. It consists of a variety of hallmark physical features, which include distinctive facial characteristics, cardiac anomalies (of which the most common is supravalvular aortic stenosis), and occasional idiopathic hypercalcemia. The condition also includes a unique cognitive profile, with relative sparing of language and facial recognition skills against a background of mental retardation. This paper reviews the early history and clinical experience with this syndrome, how it unfolds from infancy through adulthood, and how it manifests in different organ systems. Evidence-based recommendations are then offered for the treatment of the specific developmental and medical issues that arise in patients with Williams syndrome.

Longitudinal evaluation of growth, puberty, and bone maturation in children with Williams syndrome

OBJECTIVES

To establish syndrome-specific growth curves and growth rate (GR) curves for Williams syndrome (WS) and define the pattern of bone maturation and pubertal development.

METHODS

In a prospective longitudinal study between 1990 and 1997, the growth data of 244 children with WS were collected: 295 values for GR were calculated for 74 girls and 331 values for 89 boys.

RESULTS

Mean GR of children with WS was below normal by 1 to 2 cm/y in the first few years of life. One group of girls (n = 20) experienced an early pubertal growth spurt at age 9 years (maximal GR, 7.8 +/- 2.1 cm/y; menarcheal age, 10.4 +/- 1.4 years). A second group (n = 5) showed the growth spurt at age 11 years (7.5 +/- 1.1 cm/y; menarcheal age, 12.6 +/- 1.3 years). In boys, peak height velocity (8.7 +/- 2.3 cm/y) occurred at age 11 to 12 years. Bone age was delayed in both sexes during childhood and accelerated markedly during puberty. Final height was 152.4 +/- 5.7 cm in girls (n = 38) and 165.2 +/- 10. 9 cm in boys (n = 43).

CONCLUSIONS

The syndrome-specific GR curves for WS showed a premature and abbreviated pubertal growth spurt in both sexes. This growth spurt was directly related to bone age acceleration during puberty. The data from this longitudinal study provide an overview of both the dynamics of growth and its course in children with WS.