Interstitial deletion of 10q: clinical features and literature review

How chromosomal deletions can unmask recessive mutations? Deletions in 10q11.2 associated with CHAT or SLC18A3 mutations lead to congenital myasthenic syndrome

A congenital myasthenia was suspected in two unrelated children with very similar phenotypes including several episodes of severe dyspnea. Both children had a 10q11.2 deletion revealed by Single Nucleotide Polymorphisms array or by Next Generation Sequencing analysis. The deletion was inherited from the healthy mother in the first case. These deletions unmasked a recessive mutation at the same locus in both cases, but in two different genes: CHAT and SLC18A3.

Recurrent deletions and reciprocal duplications of 10q11.21q11.23 including CHAT and SLC18A3 are likely mediated by complex low-copy repeats

We report 24 unrelated individuals with deletions and 17 additional cases with duplications at 10q11.21q21.1 identified by chromosomal microarray analysis. The rearrangements range in size from 0.3 to 12 Mb. Nineteen of the deletions and eight duplications are flanked by large, directly oriented segmental duplications of >98% sequence identity, suggesting that nonallelic homologous recombination (NAHR) caused these genomic rearrangements. Nine individuals with deletions and five with duplications have additional copy number changes. Detailed clinical evaluation of 20 patients with deletions revealed variable clinical features, with developmental delay (DD) and/or intellectual disability (ID) as the only features common to a majority of individuals. We suggest that some of the other features present in more than one patient with deletion, including hypotonia, sleep apnea, chronic constipation, gastroesophageal and vesicoureteral refluxes, epilepsy, ataxia, dysphagia, nystagmus, and ptosis may result from deletion of the CHAT gene, encoding choline acetyltransferase, and the SLC18A3 gene, mapping in the first intron of CHAT and encoding vesicular acetylcholine transporter. The phenotypic diversity and presence of the deletion in apparently normal carrier parents suggest that subjects carrying 10q11.21q11.23 deletions may exhibit variable phenotypic expressivity and incomplete penetrance influenced by additional genetic and nongenetic modifiers.

Molecular cytogenetic analysis of a de novo interstitial chromosome 10q22 deletion

Interstitial deletions of 10q are rare, and only one patient with a deletion confined to chromosome band 10q22 has been reported so far. We report on a 2 6/12-year-old girl with a constitutional interstitial deletion of one homologue of 10q [karyotype: 46,XX,del(10)(q22.2q22.3)de novo]. Our patient had muscular hypotonia, developmental delay, growth retardation, mild facial dysmorphism, and hypoplastic labia minora. The precise location and extent (3.6 Mb) of the deletion was determined by fluorescence in situ hybridization (FISH) using 16 YAC and BAC clones. The clinical features in our patient are remarkably similar to the previously reported patient with a 10q22.2 deletion.

Mutations in SUFU predispose to medulloblastoma

The sonic hedgehog (SHH) signaling pathway directs the embryonic development of diverse organisms and is disrupted in a variety of malignancies. Pathway activation is triggered by binding of hedgehog proteins to the multipass Patched-1 (PTCH) receptor, which in the absence of hedgehog suppresses the activity of the seven-pass membrane protein Smoothened (SMOH). De-repression of SMOH culminates in the activation of one or more of the GLI transcription factors that regulate the transcription of downstream targets. Individuals with germline mutations of the SHH receptor gene PTCH are at high risk of developmental anomalies and of basal-cell carcinomas, medulloblastomas and other cancers (a pattern consistent with nevoid basal-cell carcinoma syndrome, NBCCS). In keeping with the role of PTCH as a tumor-suppressor gene, somatic mutations of this gene occur in sporadic basal-cell carcinomas and medulloblastomas. We report here that a subset of children with medulloblastoma carry germline and somatic mutations in SUFU (encoding the human suppressor of fused) of the SHH pathway, accompanied by loss of heterozygosity of the wildtype allele. Several of these mutations encode truncated proteins that are unable to export the GLI transcription factor from nucleus to cytoplasm, resulting in the activation of SHH signaling. SUFU is a newly identified tumor-suppressor gene that predisposes individuals to medulloblastoma by modulating the SHH signaling pathway through a newly identified mechanism.

Hydrops fetalis in an interstitial deletion of chromosome 10

We report the case of a premature neonate with ascites and dysmorphic facial features at birth. The chromosomal analysis showed an interstitial deletion of chromosome 10, that is, 46, XX, del(10)(q22.3q24.1). This is the first known case of a patient with interstitial deletion of chromosome 10 with symptoms of ascites and hydrops.

Del(10)(q22.3q24.1) associated with juvenile polyposis

Juvenile polyps are the most frequent gastrointestinal polyps with a malignant potential for which the genetic basis is unknown. Juvenile polyps, with a normal epithelium but hypertrophic lamina propria, are histologically quite distinct from adenomatous polyps which have dysplastic changes in epithelial nuclei. Furthermore, the adenomatous polyposis coli (APC) gene on Chr 5, mutated somatically in adenomatous polyps and mutated in the germline of patients with familial adenomatous polyposis, is not linked to hereditary juvenile polyposis. We provide the first report indicating that a tumor suppressor gene associated with juvenile polyposis may be located at 10q22.3q24.1. Cytogenetic studies of a patient with juvenile polyposis and multiple congenital abnormalities of the head, extremities, and abdomen revealed a de novo interstitial deletion of Chr 10 as the only defect, del(10)(10q22.3q24.1).

Hirschsprung's disease associated with a deletion of chromosome 10 (q11.2q21.2): a further link with the neurocristopathies?

We report a patient with total colonic aganglionosis in association with a deletion of part of the long arm of chromosome 10: (del(10)(q11.2q21.2)). This deletion includes the ret proto-oncogene, which has recently been implicated in multiple endocrine neoplasia type 2A (MEN 2A). The possible links between Hirschsprung's disease and the neurocristopathies and the aetiological role of abnormalities of neural crest development in these conditions are discussed.

Interstitial deletion of chromosome 10, del(10) (q11.2q22.1) in a boy with developmental delay and multiple congenital anomalies

We describe a 4-year-old boy with an interstitial deletion of the long arm of chromosome 10: del(10) (q11.2q22.1). Frontal bossing, hypertelorism, bright blue iris color, up-slanting palpebral fissures, a flat nasal bridge, a broad nose, apparently low-set ears, micrognathia, deep philtrum, and hypotonia were noted neonatally. A murmur was noted at age 5 1/2 months and surgical repair of subaortic stenosis was required at 4 years. At 4 years micrognathia was no longer evident, but the palate was high-arched. The pattern of abnormalities included postnatal-onset slow growth, short stature, mental retardation, and cardiac anomalies.

Interstitial deletion of chromosome 10q23: a new case and review

A new case of a deletion of 10q23 is described. Only two other deletions involving this region have been previously noted. A review of clinical features of these three children did not show a distinct pattern of dysmorphic features. Other interstitial deletions of 10q are listed.