Supravalvular aortic stenosis cosegregates with a familial 6;7 translocation which disrupts the elastin gene

Supravalvular aortic stenosis (SVAS) is an autosomal dominant disorder characterized by abnormalities of development of the great vessels. SVAS is also commonly part of Williams syndrome. Linkage to the elastin gene on chromosome 7q11 has recently been reported in two kindreds with SVAS. Previous reports of patients with 7q11 deletions have noted great vessel abnormalities in some. We report on a family in which SVAS is cosegregating with a balanced reciprocal translocation, t(6:7) (p21.1;q11.23), providing further evidence that SVAS is the result of mutation of elestin at 7q11.23 region. The propositus of the translocation family has some minor anomalies which occur in Williams syndrome, Suggesting that elestin abnormalities may cause some of the abnormalities found in Williams syndrome. © 1993 Wiley-Liss, Inc. © 1993 Wiley-Liss, Inc.     

Williams-Beuren syndrome: phenotypic variability and deletions of chromosomes 7, 11, and 22 in a series of 52 patients.

Fluorescence in situ hybridisation (FISH) and conventional chromosome analysis were performed on a series of 52 patients with classical Williams-Beuren syndrome (WBS), suspected WBS, or supravalvular aortic stenosis (SVAS). In the classical WBS group, 22/23 (96%) had a submicroscopic deletion of the elastin locus on chromosome 7, but the remaining patient had a unique interstitial deletion of chromosome 11 (del(11)(q13.5q14.2)). In the suspected WBS group 2/22 (9%) patients had elastin deletions but a third patient had a complex karyotype including a ring chromosome 22 with a deletion of the long arm (r(22)(p11-->q13)). In the SVAS group, 1/7 (14%) had an elastin gene deletion, despite having normal development and minimal signs of WBS. Overall, some patients with submicroscopic elastin deletions have fewer features of Williams-Beuren syndrome than those with other cytogenetic abnormalities. These results, therefore, emphasise the importance of a combined conventional and molecular cytogenetic approach to diagnosis and suggest that the degree to which submicroscopic deletions of chromosome 7 extend beyond the elastin locus may explain some of the phenotypic variability found in Williams-Beuren syndrome.     

Vocal cord abnormalities in Williams syndrome: a further manifestation of elastin deficiency

Williams syndrome (WS) is due to a deletion in the WS critical region at 7q11.23 which includes the elastin gene (ELN). One of the most characteristic features of this disorder is a harsh, brassy, or hoarse voice but the etiology of the vocal characteristics are unknown. We report two patients with WS who had bilateral vocal cord abnormalities, bringing to four the number of children with WS in whom such defects have been documented. We suggest that vocal cord abnormalities may be a far more common feature of WS than has been previously suspected, and that mild vocal cord dysfunction caused by abnormal vocal cord elastin may be the cause of the hoarse voice in this condition.     

Parallel deletion and duplication at 7q11.23 in a silent carrier for two reciprocal syndromic disorders

Partial deletions at chromosome 7q11.23 are causative for the autosomal-dominant Williams–Beuren syndrome (WBS), whereas the partial duplication of this region leads to the 7q11.23 duplication syndrome. Both syndromes are highly penetrant and occur with a frequency of 1:7500–10,000 (WBS) and 1:13,000–20,000 (7q11.23 duplication syndrome). They are associated with multiple organ defects, intellectual disability, and typical facial dysmorphisms showing broad phenotypic variability. The 7q11.23 region is susceptible to chromosomal rearrangements due to flanking segmental duplications and regions of long repetitive DNA segments. Here, we report on a family with two children affected by WBS and clinically unaffected parents. Interestingly, metaphase fluorescence in situ hybridization (FISH) revealed a deletion on 7q11.23 in the father. Intensive genetic testing, using interphase FISH, whole genome sequencing and optical genome mapping led to the confirmation of a 1.5 Mb deletion at one 7q11.23 allele and the identification of a reciprocal 1.8 Mb duplication at the other allele. This finding is highly important regarding genetic counseling in this family. The father is a silent carrier for two syndromic disorders, thus his risk to transmit a disease-causing allele is 100%. To the best of our knowledge we, here, report on the first case in which the phenotype of a microdeletion/microduplication syndrome was compensated by its reciprocal counterpart.     

A gene-dosage PCR method for the detection of elastin gene deletions in patients with Williams syndrome

Williams syndrome (WS) is a multisystem developmental disorder associated with microdeletions at 7q11.23 that involve several genes, including the elastin gene. Using genomic DNA from a panel of normal individuals and WS patients with established hemizygosity of the elastin gene locus, we have developed a quantitative polymerase chain reaction (PCR)-based gene-dosage assay that rapidly detects the loss of one allele of the elastin gene. Using this procedure, we also studied a family in which the proband was previously diagnosed with WS and her mother with a balanced 7q translocation [t(7:11)(q34;q13)]. Using DNA isolated from buccal smears obtained from several individuals in this family we were able to establish normal disomy at 7q in all family members except for the proband, in which we established hemizygosity at the elastin gene locus. We were also able to successfully infer normal disomy in an unborn child in this family. The rapid diagnostic procedure described here may have a variety of applications, including fine mapping of deletion breakpoints at 7q11.23 associated with WS.     

Smaller and larger deletions of the Williams Beuren syndrome region implicate genes involved in mild facial phenotype,epilepsy and autistic traits

Williams Beuren syndrome (WBS) is a multisystemic disorder caused by a hemizygous deletion of 1.5 Mb on chromosome 7q11.23 spanning 28 genes. A few patients with larger and smaller WBS deletion have been reported. They show clinical features that vary between isolated SVAS to the full spectrum of WBS phenotype, associated with epilepsy or autism spectrum behavior. Here we describe four patients with atypical WBS 7q11.23 deletions. Two carry ∼3.5 Mb larger deletion towards the telomere that includes Huntingtin-interacting protein 1 (HIP1) and tyrosine 3-monooxygenase/tryptophan 5-monooxigenase activation protein gamma (YWHAG) genes. Other two carry a shorter deletion of ∼1.2 Mb at centromeric side that excludes the distal WBS genes BAZ1B and FZD9. Along with previously reported cases, genotype–phenotype correlation in the patients described here further suggests that haploinsufficiency of HIP1 and YWHAG might cause the severe neurological and neuropsychological deficits including epilepsy and autistic traits, and that the preservation of BAZ1B and FZD9 genes may be related to mild facial features and moderate neuropsychological deficits. This report highlights the importance to characterize additional patients with 7q11.23 atypical deletions comparing neuropsychological and clinical features between these individuals to shed light on the pathogenic role of genes within and flanking the WBS region.     

Deletions at chromosome regions 7q11.23 and 7q36 in a patient with Williams syndrome

We report on a patient with Williams syndrome and a complex de novo chromosome rearrangement, including microdeletions at 7q11.23 and 7q36 and additional chromosomal material at 7q36. The nature of this additional material was elucidated by spectral karyotyping and first assigned to chromosome 22. Subsequent fluorescence in situ hybridization (FISH) experiments showed that it consisted of satellite material only. Refinement of the 7q36 breakpoint was performed with several FISH probes, showing a deletion distal to the triphalangeal thumb (TPT) region. The phenotype of the patient principally results from the microdeletion of the 7q11.23; the small deletion at 7qter and the extra satellite material may not be of clinical significance.     

An interstitial deletion of chromosome 7 at band q21: a case report and review

We report on a girl with moderate developmental delay and mild dysmorphic features. Cytogenetic investigations revealed a de novo interstitial deletion at the proximal dark band on the long arm of chromosome 7 (7q21.1-q21.3) in all analyzed G-banded metaphases of lymphocytes and fibroblasts. Fluorescence in situ hybridization (FISH) and molecular studies defined the breakpoints at 7q21.11 and 7q21.3 on the paternal chromosome 7, with the proximal deletion breakpoint between the elastin gene (localized at 7q11.23) and D7S2517, and the distal breakpoint between D7S652 and the COL1A2 gene (localized at 7q21.3-q22.1). Deletions of interstitial segments at the proximal long arm of chromosome 7 at q21 are relatively rare. The karyotype-phenotype correlation of these patients is reviewed and discussed. The clinical findings of patients with a deletion at 7q21 significantly overlap with those of patients with maternal uniparental disomy of chromosome 7 (matUPD(7)) and Silver-Russell syndrome (SRS, OMIM 180860). Therefore, 7q21 might be considered a candidate chromosomal region for matUPD(7) and SRS.     

Familial insertion (3;5)(q25.3;q22.1q31.3) with deletion or duplication of chromosome region 5q22.1-5q31.3 in ten unbalanced carriers

We report on the clinical and cytogenetic data of a large family with an unbalanced insertion translocation (3;5)(q25.3;q22.1q31.3). Analysis of GTG-banded chromosomes demonstrated that unbalanced inheritance of a parental insertion translocation caused either a partial deletion or duplication 5q in this family. The derivative chromosomes were characterized further using microdissection and FISH with band-specific probes. The clinical picture of the proband with a partial deletion of chromosome 5 was characterized by moderate psychomotor retardation, mild facial dysmorphism, cleft palate, and single transverse crease. The family members with a partial duplication of chromosome 5 were borderline intelligent, had mild facial dysmorphism, a cardiac anomaly, and a high-pitched voice. The unbalanced carriers were compared with patients reported in the literature with a duplication or deletion of chromosome region 5q22.1 --> 5q31.3.     

Molecular cytogenetic characterization of an insertional translocation, ins(6;7)(p25;q33q34): deletion/duplication of 7q33-34 and clinical correlations

A balanced insertional translocation between chromosomes 6 and 7, ins(6;7)(p25;q33q34) has been extensively investigated. The insertional translocation was found in several members of a three-generation family, where some were healthy balanced carriers while others had clinical symptoms due to deletion or duplication of 7q33-34. The deleted/duplicated segment could only be detected using high resolution banding and fluorescent in situ hybridization. A number of BAC/PAC clones located on chromosome 6 and 7 were used to characterize the breakpoint regions in detail and to determine the size of the deletion, which was 7.6 Mb, containing up to 68 genes. However, the insert on chromosome 6 was only 7.4 Mb, due to a deletion of 227 kb at the distal breakpoint on 7q. This small deletion was also found in the "balanced" carriers, and although the chromosome segment contains at least eight genes, none of the carriers seem to be affected by haploinsufficiency, since the phenotype is apparently normal. This is the first detailed characterization and phenotype correlation of such a deletion/duplication of distal 7q.     

GTF2I hemizygosity implicated in mental retardation in Williams syndrome: genotype-phenotype analysis of five families with deletions in the Williams syndrome region

Most individuals with Williams syndrome (WS) have a 1.6 Mb deletion in chromosome 7q11.23 that encompasses the elastin (ELN) gene, while most families with autosomal dominant supravalvar aortic stenosis (SVAS) have point mutations in ELN. The overlap of the clinical phenotypes of the two conditions (cardiovascular disease and connective tissue abnormalities such as hernias) is due to the effect of haploinsufficiency of ELN. SVAS families often have affected individuals with some WS facial features, most commonly in infancy, suggesting that ELN plays a role in WS facial gestalt as well. To find other genes contributing to the WS phenotype, we studied five families with SVAS who have small deletions in the WS region. None of the families had mental retardation, but affected family members had the Williams Syndrome Cognitive Profile (WSCP). All families shared a deletion of LIMK1, which encodes a protein strongly expressed in the brain, supporting the hypothesis that LIMK1 hemizygosity contributes to impairment in visuospatial constructive cognition. While the deletions from the families nearly spanned the WS region, none had a deletion of FKBP6 or GTF2I, suggesting that the mental retardation seen in WS is associated with deletion of either the centromeric and/or telomeric portions of the region. Comparison of these five families with reports of other individuals with partial deletions of the WS region most strongly implicates GTF2I in the mental retardation of WS.     

Alagille syndrome with interstitial 20p deletion derived from maternal ins(7;20)

We present a 6-year-old Chinese boy with Alagille syndrome and an interstitial 20p deletion, with a karyotype of 46,XY,der(20)dir ins(7;20)(q11.23;p11.23p12.2 or p12.2p13)mat. He had a peculiar face and suffered from congenital heart disease, growth retardation, severe cholestasis, hepatosplenomegaly, and impaired renal function. The karyotype of his mother showed a balanced translocation, 46,XX,dir ins(7;20)(q11.23;p11.23p12.2 or p12.2p13), and her phenotype was normal. His dead elder brother was highly suspected as another victim of Alagille syndrome. The findings in the present family suggested that if Alagille syndrome is a single gene defect, the putative gene responsible for the syndrome would not be located at the insertion breakpoints but located within the deletion extent. © 1996 John Wiley-Liss, Inc.     

Atypical 7q11.23 deletions excluding ELN gene result in Williams–Beuren syndrome craniofacial features and neurocognitive profile

Williams–Beurens syndrome (WBS) is a rare genetic disorder caused by a recurrent 7q11.23 microdeletion. Clinical characteristics include typical facial dysmorphisms, weakness of connective tissue, short stature, mild to moderate intellectual disability and distinct behavioral phenotype. Cardiovascular diseases are common due to haploinsufficiency of ELN gene. A few cases of larger or smaller deletions have been reported spanning towards the centromeric or the telomeric regions, most of which included ELN gene. We report on three patients from two unrelated families, presenting with distinctive WBS features, harboring an atypical distal deletion excluding ELN gene. Our study supports a critical role of CLIP2, GTF2IRD1, and GTF2I gene in the WBS neurobehavioral profile and in craniofacial features, highlights a possible role of HIP1 in the autism spectrum disorder, and delineates a subgroup of WBS individuals with an atypical distal deletion not associated to an increased risk of cardiovascular defects.     

Spectrum of elastin sequence variants and cardiovascular phenotypes in 49 patients with Williams–Beuren syndrome

Haploinsufficiency of the elastin gene (ELN) on 7q11.23 is responsible for supravalvular aortic stenosis (SVAS) and other arteriopathies in patients with Williams–Beuren syndrome (WBS). These defects occur with variable penetrance and expressivity, but the basis of this is unknown. To determine whether DNA variations in ELN could serve as genetic modifiers, we sequenced the 33 exons and immediately surrounding sequence of the ELN gene (9,455 bp of sequence) in 49 DNAs from patients with WBS and compared cardiovascular phenotypes. Four missense, and four novel intronic variants were identified from a total of 24 mostly intronic single nucleotide variations and one indel. Two missense changes were present in one patient each, one published, p.Gly610Ser in exon 27 (MAF, 0.003) and one novel, p.Cys714Tyr, in exon 33 (MAF, 0.001), were rare in the general population. To identify a statistical association between the variants identified here and cardiovascular phenotypes a larger cohort would be needed. © 2013 Wiley Periodicals, Inc.     

Unequal interchromosomal rearrangements may result in elastin gene deletions causing the Williams-Beuren syndrome

Williams-Beuren syndrome (WBS) is generally the consequence of an interstitial microdeletion at 7q11.23, which includes the elastin gene, thus causing hemizygosity at the elastin gene locus. The origin of the deletion has been reported by many authors to be maternal in approximately 60% and paternal in 40% of cases. Segregation analysis of grandparental markers flanking the microdeletion region in WBS patients and their parents indicated that in the majority of cases a recombination between grandmaternal and grandpaternal chromosomes 7 at the site of the deletion had occurred during meiosis in the parent from whom the deleted chromosome stemmed. Thus, the majority of deletions were considered a consequence of unequal crossing-over between homologous chromosomes 7 (interchromosomal rearrangement) while in the remaining cases an intrachromosomal recombination (between the chromatids of one chromosome 7) may have occurred. These results suggest that the majority of interstitial deletions of the elastin gene region occur during meiosis, due to unbalanced recombination while a minority could occur before or during meiosis probably due to intrachromosomal rearrangements. The recurrence risk of the interchromosomal rearrangements for sibs of a proband with non-affected parents must be negligible, which fits well with the observation of sporadic occurrence of almost all cases of WBS.      

Portal hypertension in Williams syndrome: report of two patients

Williams or Williams-Beuren syndrome (WBS) is a developmental disorder with multisystemic manifestations characterized by distinctive facial features, mental disability with unique cognitive and personality profiles, vascular stenoses, growth retardation, and occasional infantile hypercalcemia, caused by haploinsufficiency for genes deleted in chromosome band 7q11.23. However, with the exception of arterial stenoses caused by haploinsufficiency for the elastin gene (ELN), no specific implication of any other gene in the phenotype has been established. We present two patients with portal hypertension leading to splenomegaly and pancytopenia carrying the common 1.5 Mb WBS deletion. We propose this is an additional severe vascular complication of ELN deficiency and discuss the specific characteristics of the portal venous tract that could explain the impact of ELN deficiency in that venous territory. This complication is potentially lethal and should thus be considered in any patient with WBS and splenomegaly.     

Molecular analysis of a t(11;14)(q23;q11) from a patient with null-cell acute lymphoblastic leukemia

/1p;&-3qChromosome 11, band q23, is the frequent site of recurring cytogenetic rearrangements in human leukemia. We have cloned and sequenced the breakpoint junctions from a patient who had null-cell acute lymphoblastic leukemia (ALL) with a t(11;14)(q23;q11). The chromosome 14 breakpoints occurred within the TCRD locus, close to two diversity segments. The chromosome 11 breakpoint occurred between two head-to-head heptamer sequences, and junctional diversity was evident at both derivative junctions, suggesting involvement of the V(D)J recombinase. The TCRA/D locus on the normal chromosome 14 had undergone a Vδ2-Dδ3-ΨJα joining. Two phage clones with this VDJ rearrangement were isolated; one of these contained an intra-Jα region deletion. Two clones with the derivative 11 junction were isolated; one of these had a similar, but not identical, deletion. A heptamer-nonamer recognition sequence (located ～70 kb 5′ to Cα), not associated with a TCR gene coding segment, was found in the immediate vicinity of both 5′ breakpoints. We have designated this sequence 5′^del for 5′ deleting element. An intra-Jα region deletion involving this heptamer-nonamer was previously identified in the leukemia cells recovered from a patient who had T-cell ALL. Fifty kilobases of DNA on 11q23 surrounding the breakpoint were cloned and analyzed. No CpG islands or conserved sequences were identified within this region. Fluorescence in situ hybridization analysis showed that this 11q23 breakpoint mapped distal to the MLL gene associated with the recurring breakpoints in the 4;11, 9;11, and 11;19 translocations, distal to the RCK gene associated with an 11;14 translocation, and proximal to the ETSI gene, which is located at 11q24. © 1993 Wiley-Liss, Inc.     

Terminal 4q deletion and 8q duplication in a patient with CHARGE-like features

The CHARGE syndrome is a multiple congenital malformation syndrome that usually results from deletion or heterozygous loss of function mutations of the chromodomain helicase DNA-binding protein 7 (CHD7) gene at 8q12.1. Besides CHD7-related cases, some patients with CHARGE-like phenotype have been reported with chromosomal imbalances. We describe a patient with a pattern of malformations reminiscent of CHARGE syndrome: choanal atresia, facial dysmorphism (micrognathia, hypertelorism, epicanthic folds, and depressed, broad nasal bridge), cardiovascular malformations, cryptorchidism, and developmental delay. He had duplication 8q and deletion 4q derived from paternal translocation t(4;8)(q34;q22.1). CHD7 mutation or deletion was excluded. The present report to the best of our knowledge is the only one describing an unbalanced translocation t(4;8) and CHARGE-like phenotype.