Deletion (11)(q14.1q21)

Interstitial deletion at 11q14.2-11q22.1 may cause severe learning difficulties, mental retardation and mild heart defects in 13-year old male

Interstitial deletions of the long arm of chromosome 11 are rare, and they could be assumed as non-recurrent chromosomal rearrangements due to high variability of the size and the breakpoints of the deleted region. The exact region of the deletion was difficult to be determined before the use of molecular cytogenetic techniques such as array comparative genomic hybridization (aCGH). Here, a 13-year old boy with severe learning difficulties, mental retardation and mild heart defects is described. Conventional G-band karyotyping was performed and it is found that the patient is a carrier of a de novo interstitial deletion on the long arm of chromosome 11, involving 11q14 and 11q22 breakpoints. Further investigation, using aCGH, specified the deleted region to 11q14.2-11q22.1. There was a difficulty in correlating the genotype with the phenotype of the patient due to lack of similar cases in literature. More studies should be done in order to understand the genetic background that underlies the phenotypic differences observed in similar cases.

Interstitial 11q deletion: genomic characterization and neuropsychiatric follow up from early infancy to adolescence and literature review

BACKGROUND

Interstitial deletions of chromosome 11 long arm are rarely observed and the associated phenotype ranges from normal to severe, depending on the position and size of the deletion and on the presence of unmasked recessive genes on the normal homologous. To our knowledge 32 cases are reported in literature with three family cases. Phenotype-genotype correlation is not very clear and the most common features are characteristic facial dysmorphisms, palate anomalies and developmental delay. Growth retardation is not typical and other major malformations are reported in some cases.

CASE PRESENTATION

We described a child with 11q interstitial deletion diagnosed at birth with hypotonia and minor dysmorphisms using standard cytogenetic techniques; array CGH was subsequently performed to define the deletion at a molecular level.

CONCLUSIONS

This case gave us the opportunity to attempt a genotype-phenotype correlation reviewing the literature and to describe a rehabilitative program that improved the development perspectives of this child.

Interstitial 11q deletion derived from a maternal ins(4;11)(p14;q24.2q25): a patient report and review

We present a family with multiple cytogenetic abnormalities, identified through a girl with several dysmorphic features and cardiac problems, suspected for Jacobsen syndrome. Cytogenetic analysis showed a 46,XX,del(11)(qter) karyotype, which was confirmed by fluorescence in situ hybridization (FISH). Cytogenetic investigation of the parents showed a chromosome aberration in both: the father had a t(11;12)(p13;q22) translocation and the mother was carrier of an ins(4;11)(p14;q24q25). FISH analysis with an 11q-subtelomeric probe from the second-generation telomere clone set and BACs from 11q24-q25 suggested a complex maternal rearrangement. However, subsequent array analysis showed a single interstitial deletion in the proband, derived from the maternal insertion. The aberrant karyotypes in both parents implicated an increased risk of unbalanced fetal chromosome composition, thus high risk for a child with multiple congenital abnormalities. Therefore, during the next pregnancy, the couple opted for prenatal diagnosis by means of amniocentesis. An interphase FISH strategy for uncultured amniotic fluid cells predicted two possible unbalanced fetal chromosome constitutions. Karyotyping of cultured amniotic cells confirmed one of the predicted unbalanced cytogenetic options, demonstrating the value of a fast interphase strategy for parents who both are carriers of a chromosomal abnormality. In addition, we present an overview of patients with Jacobsen syndrome and an interstitial 11q deletion reported thus far in literature.

A new case of de novo 11q duplication in a patient with normal development and intelligence and review of the literature

A new case of 11q interstitial duplication is reported in a patient with mild dysmorphic features but normal development. Chromosome analysis revealed a de novo 11q dup(11)(q14.1q21) on G banding and FISH studies. Additional molecular genetic studies revealed a similar but more distal duplication at the level of 11q21q23.1. Previous cases of isolated 11q duplication that overlapped with this case were associated with a wide variety of clinical findings and variable developmental disability. These cases all included additional material not duplicated in this patient. The current case represents the first de novo case of 11q duplication with normal development suggesting that the segment between 11q14.1 and 11q21 contains few genes that are dose sensitive. Review of other cases that have used conventional cytogenetic resolution studies suggests that the band 11q13.5 may contain genes contributing to the developmental disabilities in the cases previously reported with proximal 11q duplication. Differences between conventional cytogenetic techniques and newer molecular genetic studies are expected. These newer techniques will help refine prognosis and counseling for families in the future.

Karyotype-phenotype insights from 11q14.1-q23.2 interstitial deletions: FZD4 haploinsufficiency and exudative vitreoretinopathy in a patient with a complex chromosome rearrangement

We detected a unique de novo complex chromosome rearrangement (CCR) in a patient with multiple abnormalities including growth retardation, facial anomalies, exudative vitreoretinopathy (EVR), cleft palate, and minor digital anomalies. Cytogenetic analysis, fluorescent in situ hybridization, and microsatellite genotyping showed a reciprocal translocation between chromosomes 5 and 8, and a complex translocation-deletion-inversion process in the formation of derivative chromosomes 11 and 16. High-density whole-genome oligonucleotide array comparative genomic hybridization (oaCGH) defined a 35-megabase interstitial deletion of 11q14.1-q23.2 and a 1 megabase deletion of 16q22.3-q23.1. The Frizzled-4 (FZD4) gene is located within this 11q deletion. Parental studies and sequencing analysis confirmed that the patient was hemizygous for FZD4 due to the loss of a paternal allele on the derivative chromosome 11. Mutations in FZD4 are known to cause autosomal dominant exudative vitreoretinopathy (EVR1). Our patient's findings suggest that haploinsufficiency of the FZD4 gene product can also be a disease-causing mechanism for EVR1. We reviewed the clinical manifestations of 23 cases with 11q14-q23 interstitial deletions, with particular scrutiny of the present case and four reported cases characterized by molecular cytogenetics. These findings were used to construct a regional deletion map consisting of a haplosufficient segment at 11q14.3, a flanking centromeric segment at 11q14.1-q14.2, and a flanking telomeric segment at 11q21-q23.3. We propose that deletions of the FZD4 gene located within the centromeric segment cause retinal dysgenesis, while deletions within the telomeric segment account for dysmorphic craniofacial features, growth and mental retardation, and mild digital anomalies. These results provide insight into karyotype-phenotype correlations and prompt a rational analytic approach to cases with interstitial deletions of the 11q14-q23 region.

Syndromes and constitutional chromosomal abnormalities associated with Wilms tumour

Wilms tumour has been reported in association with over 50 different clinical conditions and several abnormal constitutional karyotypes. Conclusive evidence of an increased risk of Wilms tumour exists for only a minority of these conditions, including WT1 associated syndromes, familial Wilms tumour, and certain overgrowth conditions such as Beckwith-Wiedemann syndrome. In many reported conditions the rare co-occurrence of Wilms tumour is probably due to chance. However, for several conditions the available evidence cannot either confirm or exclude an increased risk, usually because of the rarity of the syndrome. In addition, emerging evidence suggests that an increased risk of Wilms tumour occurs only in a subset of individuals for some syndromes. The complex clinical and molecular heterogeneity of disorders associated with Wilms tumour, together with the apparent absence of functional links between most of the known predisposition genes, suggests that abrogation of a variety of pathways can promote Wilms tumorigenesis.

Wilms' tumor and horseshoe kidneys: a case report and review of the literature

The presence of Wilms' tumor with a horseshoe kidney is an unusual combined clinical presentation. It has been reported that the incidence of Wilms' tumor in patients with horseshoe kidneys is higher than that seen in the general population. The current report describes a 5-year-old boy who presented with a stage III Wilms' tumor in a horseshoe kidney. The patient was treated with neoadjuvant chemotherapy followed by surgical resection, adjuvant chemotherapy, and radiation. The patient is disease free 40 months after diagnosis. A review of all reported cases of Wilms' tumor with horseshoe kidneys in the English-language literature before July 2002 is presented.

Human NB-2 of the contactin subgroup molecules: chromosomal localization of the gene (CNTN5) and distinct expression pattern from other subgroup members

NB-2 is one of the neural recognition molecules in the contactin subgroup, which belongs to the immunoglobulin superfamily. In rat, the six molecules in this subgroup that have been reported to date are contactin, TAG-1, BIG-1, BIG-2, NB-2, and NB-3. We have isolated cDNAs encoding the two splicing isoforms of human NB-2. The long isoform of human NB-2 consists of 1100 amino acids residues that are 91% homologous to rat NB-2 at the amino acid sequence level. The short isoform lacks 74 amino acid residues between residues 19 and 93 of the long isoform. Among various regions of the adult human brain, high-level expression of NB-2 was detected in the amygdala and occipital lobe, whereas expression was low in the corpus callosum, caudate nucleus, and spinal cord. Although there were some differences, the expression pattern of NB-2 was the most similar to that of BIG-1 in the brain. Likewise, contactin and BIG-2 exhibited similar expression patterns. The expression of TAG-1 showed the least regional differences. The human NB-2 gene (CNTN5) was mapped to chromosome 11q21-q22.2 by fluorescence in situ hybridization. Our results suggest that the NB-2 gene may contribute to human neurological disorders.

Isolated central form of tetrahydrobiopterin deficiency associated with hemizygosity on chromosome 11q and a mutant allele of PTPS

6-Pyruvoyl-tetrahydropterin synthase (PTS or PTPS) is involved in tetrahydrobiopterin (BH(4)) biosynthesis, the cofactor for various enzymes including the aromatic amino acid hydroxylases. Inherited PTPS deficiency is a heterogeneous disease with different phenotypes leading to BH(4) depletion. The severe form of PTPS deficiency causes hyperphenylalaninemia and monoamine neurotransmitter deficiency, whereas the mild form gives rise to hyperphenylalaninemia only. From 228 patients with PTPS deficiency at least 32 different mutant alleles have been identified on its corresponding gene, located on chromosome 11q22.3-q23.3. Here we describe a new allele from a child with PTPS deficiency who exhibited a mild but transient form of hyperphenylalaninemia, yet was deficient in CSF monoamines. The patient was found to carry, on her genomic DNA and cDNA, a homozygous A>G transition, leading to PTPS codon alteration Tyr99 to Cys (Y99C). The mother and several members of the maternal family were carriers of the Y99C allele, also verified by the reduced PTPS enzyme activity in erythrocytes. By cytogenetic, molecular, and FISH analyses, a de novo deletion spanning from 11q14 to 11q23.3 on the patient's paternal chromosome was mapped, establishing hemizygosity of the Y99C allele. The PTPS mutation observed in this patient generates a novel phenotype with an apparently isolated central form of BH(4) deficiency.

Jacobsen syndrome: report of a patient with severe eye anomalies, growth hormone deficiency, and hypothyroidism associated with deletion 11 (q23q25) and review of 52 cases

We have evaluated a patient with Jacobsen syndrome. The patient presented with growth retardation, hypotonia, trigonocephaly, telecanthus, downward slanting palpebral fissures, bilateral inferior colobomas (of the iris, choroid, and retina), hydrocephalus, central nervous system (CNS) abnormalities, and an endocardial cushion defect, features commonly seen in Jacobsen syndrome. Endocrine evaluation showed growth hormone deficiency and central hypothyroidism. Chromosome analysis showed a 46,XX,del(11)(q23q25) de novo karyotype. Cytogenetically, the deletion appeared to include most of bands 11q23 and q24 and a portion of q25. Using chromosome specific paint probe, a combination of chromosome 11 centromere, telomere, and region specific cosmid probes from 11q14.1-14.3, 11q23.3, and 11q24.1, we have localised the deletion breakpoint to q24.1. Phenotype-karyotype correlation of patients with Jacobsen syndrome and specific deletions of chromosome 11q has enabled us to suggest that the critical region for this syndrome lies in close proximity to cytogenetic band 11q24. Although growth retardation is a consistent finding in 11q deletion syndrome, the presence of hypothalamic-pituitary hormone deficiency has not been reported previously.

Partial deletion 11q: report of a case with a large terminal deletion 11q21-qter without loss of telomeric sequences, and review of the literature

We describe the cytogenetic findings and the dysmorphic features in a stillborn girl with a large de novo terminal deletion of the long arm of chromosome 11. The karyotype was 46,XX,del(11)(q21qter). By reviewing previous reports of deletion 11q, we found that cleft lip and palate are most frequently seen in proximal 11q deletions involving 11q21. Telomeric staining using the PRINS technique demonstrated normal telomeric sequences in the deleted chromosome 11.