Proximal interstitial deletion of 7q: a case report and review of the literature

Interstitial deletion of 7q22.1q31.1 in a boy with structural brain abnormality, cardiac defect, developmental delay, and dysmorphic features

This report describes a male child with a history of poor feeding and swallowing problems, hypotonia, mild bilateral sensorineural hearing loss, cerebral cortical agenesis, cardiac defects, cyanotic episodes triggered by specific movement, dysmorphic features, and developmental delays. Analysis by CytoScan HD array identified a 12.1 Mb interstitial deletion of 7q22.1q31.1 (98,779,628-110,868,171). We present a comprehensive review of the literature surrounding intermediate 7q deletions that overlap with this child's deletion, and an analysis of candidate genes in the deleted region. © 2016 Wiley Periodicals, Inc.

Epilepsy is a possible feature in Williams-Beuren syndrome patients harboring typical deletions of the 7q11.23 critical region

Seizures are rarely reported in Williams-Beuren syndrome (WBS)--a contiguous-gene-deletion disorder caused by a 7q11.23 heterozygous deletion of 1.5-1.8 Mb--and no previous study evaluated electro-clinical features of epilepsy in this syndrome. Furthermore, it has been hypothesized that atypical deletion (e.g., larger than 1.8 Mb) may be responsible for a more pronounced neurological phenotypes, especially including seizures. Our objectives are to describe the electro-clinical features in WBS and to correlate the epileptic phenotype with deletion of the 7q11.23 critical region. We evaluate the electro-clinical features in one case of distal 7q11.23 deletion syndrome and in eight epileptic WBS (eWBS) patients. Additionally, we compare the deletion size-and deleted genes-of four epileptic WBS (eWBS) with that of four non-epileptic WBS (neWBS) patients. Infantile spasms, focal (e.g., motor and dyscognitive with autonomic features) and generalized (e.g., tonic-clonic, tonic, clonic, myoclonic) seizures were encountered. Drug-resistance was observed in one patient. Neuroimaging discovered one case of focal cortical dysplasia, one case of fronto-temporal cortical atrophy and one case of periventricular nodular heterotopia. Comparison of deletion size between eWBS and neWBS patients did not reveal candidate genes potentially underlying epilepsy. This is the largest series describing electro-clinical features of epilepsy in WBS. In WBS, epilepsy should be considered both in case of typical and atypical deletions, which do not involve HIP1, YWHAG or MAGI2.

Prenatal diagnosis of a 7q21.13q22.1 deletion detected using high-resolution microarray

We report a case of de novo 7q interstitial deletion detected by conventional karyotyping and by microarray of amniotic fluid sampled during the prenatal period. A 32-year-old pregnant woman was evaluated at our hospital following detection of increased nuchal translucency at 12 weeks and 5 days of gestation. Conventional karyotyping revealed 46,XX,del(7)(q21q22) in 20 interphase mitotic cells, and high-resolution microarray revealed 12.8 Mb (90,625,014-103,430,901) deletion in the region 7q21.13q22.1. Both parents had normal karyotypes. After birth, the neonate displayed several anomalies, including palatine cleft, upslanted and wide palpebral fissure, low-set ears, micrognathia, microcephaly, ventriculomegaly, subglottic tracheal stenosis, hearing loss, and hand/foot deformities, including brachydactyly, polydactyly, and cutaneous syndactyly. This case study helps explain the phenotype-genotype relationship in patients with 7q21.13q22.1 deletion.

Two female siblings with West syndrome: Familial idiopathic West syndrome with genetic susceptibility and variable phenotypic expression

The West syndrome (WS) is a characteristic form of epilepsy which usually begins in the first year of life. We describe two female siblings, aged 4 and 2 years, respectively, born from third degree consanguineous parents, with infantile spasms and developmental delay. Epileptic spasms had not a good outcome under antiepileptic drug treatment. Clinical and imaging features were of different severity in both siblings. Routine biochemical tests, metabolic investigations, and chromosomal analysis were normal. We analyzed CDKL5 gene by direct sequences and denaturing high-performance liquid chromatography using Transgenomic WAVE system. Analysis of the CDKL5 gene, which is responsible for female patient with WS, did not show any disease-causing mutation. WS has heterogeneous backgrounds, and may be more than one gene is responsible for its familial forms. In this family, consanguinity is observed in parents, which usually suggests that autosomal recessive inheritance is likely.

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.

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.

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.

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.

Ectrodactyly and proximal/intermediate interstitial deletion 7q

We report on an individual with severe mental retardation, seizures, microcephaly, unusual face, scoliosis, and cleft feet and cleft right hand. The chromosomal study showed a proximal interstitial deletion 7q (q11.23q22). From our review of the literature, 11 patients have been reported with ectrodactyly (split hand/split foot malformation) and proximal/intermediate interstitial deletions or rearrangements of 7q. The critical segment for ectrodactyly seems to be located between 7q21.2 and 7q22.1. This malformation is present in 41% of the patients whose deletion involves the critical segment.

Smith-Lemli-Opitz syndrome in a female with a de novo, balanced translocation involving 7q32: probable disruption of an SLOS gene

A 3-month-old infant girl had manifestations of the Smith-Lemli-Opitz syndrome (SLOS) including typical positional anomalies of the limbs, apparent Hirschsprung disease, cataracts, ptosis, anteverted nares, cleft of the posterior palate, small tongue, broad maxillary alveolar ridges, and abnormally low serum cholesterol levels. Chromosomal analysis showed a de novo balanced translocation interpreted as 46,XX,t(7;20)(q32.1;q13.2). We hypothesize that the translocation breakpoint in this case interrupts one SLOS allele and that the other allele at the same locus has a more subtle mutation that was inherited from the other parent. This case, as well as cytogenetic observations in other SLOS cases, suggests that SLOS could be due to autosomal recessive mutation at a gene in 7q32.

Clinical, cytogenetic, and molecular evidence for an infant with Smith-Magenis syndrome born from a mother having a mosaic 17p11.2p12 deletion

We describe an infant with del(17) (p11.2p12) whose deleted chromosome was inherited from a mosaic mother. The child had manifestations consistent with Smith-Magenis syndrome. The mother appeared to be of normal intelligence and she had minimal findings of Smith-Magenis syndrome. Separation of chromosome 17 homologues in somatic cell hybrids and molecular studies confirmed the cytogenetic diagnoses and the fact that the mother was mosaic. Furthermore, molecular analysis demonstrated novel breakpoints in this family, with the deletion extending into and completely encompassing the markers duplicated in Charcot-Marie-Tooth (CMT) disease. Although this Smith-Magenis syndrome patient is completely deleted for the CMT region, her electrophysiological findings are different from those found in CMT. This is the only reported case of Smith-Magenis syndrome with transmission from a partially affected mosaic mother. Transmission of interstitial deletions from mosaic parents may be more common than thought; therefore, parental chromosomes should be examined when interstitial deletions are identified.

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 a mutation of elastin at 7q11.23 region. The propositus of the translocation family has some minor anomalies which occur in Williams syndrome, suggesting that elastin abnormalities may cause some of the abnormalities found in Williams syndrome.

Use of fluorescence in situ hybridization to confirm the interpretation of a balanced complex chromosome rearrangement ascertained through prenatal diagnosis

A balanced complex chromosome rearrangement (BCCR) involving 3 chromosomes with 4 breakpoints, was identified in a 36-yr-old woman who was studied because her fetus was discovered to have an unbalanced reciprocal translocation (7q;10q). Analysis of high resolution bands and the application of fluorescence in situ hybridization has identified the BCCR as der(7)t(7;10)(q21.13;q23.33)ins(21;7)(q21.3;q11.22q21.13), der(10)t(7;10)(q21.13; q23.33), der(21)ins(21;7)(q21.3;q11.22q21.13). Alternate segregation of the BCCR appears to be favoured, and has resulted in two pregnancies with an unbalanced chromosome constitution.

Proximal 7q interstitial deletion in a severely mentally retarded and mildly abnormal infant

We describe a boy with an interstitial deletion of 7q [46,XY,del(7)(pter-->q11.21::q11.23-->qter)] and severe mental retardation, bilateral inguinal hernias, plagiocephaly, and mildly abnormal facial appearance. This is the 21st case report involving a proximal 7q deletion, but the first report of this specific deletion in the absence of Zellweger syndrome. Specific genotype-phenotype correlations are still not possible for this region of chromosome 7.