Chromosomal Microarray Analysis Identifies a Novel SALL1 Deletion, Supporting the Association of Haploinsufficiency with a Mild Phenotype of Townes-Brocks Syndrome.

SALL1 heterozygous pathogenic variants cause Townes-Brocks syndrome (TBS), a condition with variable clinical presentation. The main features are a stenotic or imperforate anus, dysplastic ears, and thumb malformations, and other common concerns are hearing impairments, foot malformations, and renal and heart defects. Most of the pathogenic SALL1 variants are nonsense and frameshift, likely escaping nonsense-mediated mRNA decay and causing disease via a dominant-negative mechanism. Haploinsufficiency may result in mild phenotypes, but only four families with distinct SALL1 deletions have been reported to date, with a few more being of larger size and also affecting neighboring genes. We report on a family with autosomal dominant hearing impairment and mild anal and skeletal anomalies, in whom a novel 350 kb SALL1 deletion, spanning exon 1 and the upstream region, was identified by array comparative genomic hybridization. We review the clinical findings of known individuals with SALL1 deletions and point out that the overall phenotype is milder, especially when compared with individuals who carry the recurrent p.Arg276Ter mutation, but with a possible higher risk of developmental delay. Chromosomal microarray analysis is still a valuable tool in the identification of atypical/mild TBS cases, which are likely underestimated.

Hyperinsulinemic Hypoglycaemia in a Turner Syndrome with Ring (X).

Hyperinsulinemic hypoglycaemia (HH) is a group of clinically, genetically, and morphologically heterogeneous disorders characterized by dysregulation of insulin secretion by pancreatic beta cells. HH can either be congenital genetic hyperinsulinism or associated with metabolic disorder and syndromic condition. Early identification and meticulous management of these patients is vital to prevent neurological insult. There are only three reported cases of HH associated with a mosaic, r(X) Turner syndrome. We report the four cases of an infant with a mosaic r(X) Turner genotype and HH responsive to diazoxide therapy.

Heterogeneous phenotype of human glioblastoma: in vitro study.

Glioblastomas (GBMs) are the most lethal primary brain tumours. Increasing evidence shows that brain tumours contain the population of stem cells, so-called cancer stem cells (CSCs). Stem cell marker CD133 was reported to identify CSC population in GBM. Further studies have indicated that CD133 negative cells exhibiting similar properties and are able to initiate the tumour, self-renew and undergo multilineage differentiation. GBM is a highly heterogeneous tumour and may contain different stem cell populations with different functional properties. We characterized five GBM cell lines, established from surgical samples, according to the marker expression, proliferation and differentiation potential. CD133 positive cell lines showed increased proliferation rate in neurosphere condition and marked differentiation potential towards neuronal lineages. Whereas two cell lines low-expressing CD133 marker showed mesenchymal properties in vitro, that is high proliferation rate in serum condition and differentiation in mesenchymal cell types. Further, we compared therapy resistance capacity of GBM cell lines treated with hydroxyurea. Our results suggest that CSC concept is more complex than it was believed before, and CD133 could not define entire stem cell population within GBM. At least two different subtypes of GBM CSCs exist, which may have different biological characteristics and imply different therapeutic strategies.

Acquisition of i(8q) as an early event in malignant triton tumors.

Malignant triton tumors (MTT) are rare soft-tissue tumors characterized by a mixture of cells with nerve sheath and skeletal muscle differentiation. MTT is a histological variant of malignant peripheral nerve sheath tumors (MPNST). No characteristic cytogenetic anomaly has been detected in MPNST or MTT. In this paper, we report on the cytogenetic findings of an MTT from a 20-year old male with neurofibromatosis (NF1). The tumoral karyotype showed the modal number to be near-diploid and an abnormal karyotype with a Robertsonian translocation and 4 markers: 49,XY,der(14;15)(q10;q10),+4mar. Spectral karyotyping revealed the karyotype: 49,XY, der(14;15)(q10;q10),+i(8)(q10)x4. Fluorescence in situ hybridization analysis of the tissue confirmed the presence of the additional i(8)(q10) in all tumoral cells. The sequence analysis of p53 revealed a polymorphism in exon 9, codon 329. The two alleles, TTC and TCC, codify for phenylalanine and serine, respectively. Our results indicate that all neoplastic cells have the same cytogenetic pattern, suggesting that both cell lines, which show nerve sheath and skeletal muscle differentiation, are derived from a unique stem cell. The acquired Robertsonian chromosomal recombinants might represent an event in the tumorigenesis of MTT, and the present data suggest that genes located on 8q can be involved in the development of MTT.

Cytogenetic analysis of myoepithelial cell carcinoma of salivary gland.

Myoepithelial cell carcinoma (MCC) of the salivary gland is a rare entity. Here, we describe the karyotype of MCC. The patient was a 53-year-old man, with a rapidly growing lesion of the palate. Despite complete surgical excision, radio- and chemotherapy, the lesion rapidly harboured local and distant metastases leading to the death of the patient, 4 months after the diagnosis. On histological and ultrastructural examination, the primary tumour and the related metastases were composed of oval and spindle cells, with features of myoepithelial cell differentiation reported in the literature. Cytogenetic analysis showed a composite karyotype in the primary tumour: 45-46,XY, +3[cp3]/ 44-45,XY, -17[cp4]/ 46,XY[5]. The lymph-node metastasis was near-triploid and showed a complex karyotype. Our cytogenetic data differ from those described in benign or slowly growing salivary gland tumours showing myoepithelial cell differentiation. It is suggested that highly aggressive tumours might follow a different pathway of malignant transformation.