Two new reported cases of 16q22.3q23.3 duplication syndrome highlight intrafamilial variability and potential sex expression differences within a rare duplication syndrome

Two new cases of 16q22.3q23.3 Duplication syndrome demonstrate that phenotype can vary from severely affected to mild psychiatric concerns, even within the same family and identical duplications.

A 16q22.2-q23.1 deletion identified in a male infant with West syndrome

In partial monosomy of the distal part of chromosome 16q, abnormal facial features, intellectual disability (ID), and feeding dysfunction are often reported. However, seizures are not typical and the majority of them were seizure-free. Here we present the case of a 16q22.2-q23.1 interstitial deletion identified in a male patient with severe ID, facial anomalies including forehead protrusions and flat nose bridge, patent ductus arteriosus, bilateral vocal cord atresia treated by tracheotomy, and West syndrome, which were developed 10 months after birth. Although phenobarbital, sodium valproate (VPA), and zonisamide were not effective as monotherapies or combination therapies, the patient's epileptic seizures and electroencephalogram anomalies disappeared following combined therapy with lamotrigine and VPA. Although WW Domain Containing Oxidoreductase (WWOX), which is known as a cause of autosomal recessive epileptic encephalopathy, was included within the 6.8-Mb deleted region which identified by targeted panel sequencing and validated by chromosomal microarray analysis, no pathogenic variants were detected in the other allele of WWOX. Therefore, it is possible that other genes within or outside of the long deleted region or their interactions may cause West syndrome in this patient.

Loss of Heterozygosity at Chromosome 16q Is a Negative Prognostic Factor in Korean Pediatric Patients with Favorable Histology Wilms Tumor: A Report of the Korean Pediatric Hematology Oncology Group (K-PHOG)

PURPOSE

Loss of heterozygosity (LOH) at chromosomes 1p and 16q is a poor prognostic factor in favorable histology Wilms tumor (FHWT). This study investigated the prevalence of LOH at 1p and 16q and evaluated its prognostic value in Korean children with FHWT.

MATERIALS AND METHODS

We analyzed 101 FHWT patients who were diagnosed between 1996 and 2016 in Korean Society of Pediatric Hematology Oncology Group hospitals. Using paraffin-embedded kidney tissue samples sent from each center, we reviewed LOH at 1p and 16q in each patient and assessed the prognostic value of LOH status for clinical parameters affecting event-free survival (EFS).

RESULTS

Of the 101 patients, 12 (11.9%) experienced recurrence; the 3-year EFS was 87.6%. LOH at 1p or 16q was detected in 19 patients (18.8%), with five having LOH at both 1q and 16q. The frequency of LOH at 1p was higher among younger patients (p=0.049), but there was no difference in LOH prevalence according to tumor stage. In the multivariate analysis, LOH at 16q was a significant negative prognostic factor affecting EFS (3-year EFS, 73.7% vs. 91.1%; hazard ratio, 3.95; p=0.037), whereas LOH at 1p was not (p=0.786).

CONCLUSION

LOH at 16q was a significant negative prognostic factor affecting outcome in Korean pediatric FHWT patients. Due to the small sample size of this study, large-scale multicenter trials are warranted to investigate the prognostic value of LOH at 1p and 16q in Korean children with FHWT.

Deletion lengthening at chromosomes 6q and 16q targets multiple tumor suppressor genes and is associated with an increasingly poor prognosis in prostate cancer

Prostate cancer is characterized by recurrent deletions that can considerably vary in size. We hypothesized that large deletions develop from small deletions and that this “deletion lengthening” might have a “per se” carcinogenic role through a combinatorial effect of multiple down regulated genes. In vitro knockdown of 37 genes located inside the 6q12-q22 deletion region identified 4 genes with additive tumor suppressive effects, further supporting a role of the deletion size for cancer aggressiveness. Employing fluorescence in-situ hybridization analysis on prostate cancer tissue microarrays, we determined the deletion size at 6q and 16q in more than 3,000 tumors. 16q and 6q deletion length was strongly linked to poor clinical outcome and this effect was even stronger if the length of both deletions was combined. To study deletion lengthening in cancer progression we eventually analyzed the entire cancers from 317 patients for 6q and 16q deletion length heterogeneity and found that the deletion expanded within 50-60% of 6q and 16q deleted cancers. Taken together, these data suggest continuous “deletion lengthening” as a key mechanism for prostate cancer progression leading to parallel down regulation of genes with tumor suppressive properties, some of which act cooperatively.

Profiling Loss of Heterozygosity Patterns in a Cohort of Favorable Histology Nephroblastoma Egyptian Patients: What is Consistent With the Rest of the World

According to the Fifth National Wilms Tumor Study (NWTS-5), tumor-specific loss of heterozygosity (LOH) for chromosomes 1p and 16q identifies a subset of patients with Wilms tumor (WT) who despite having favorable histology (FH) have a significantly increased risk of relapse and death. We aimed to find out 1p and 16q LOH frequencies in patients with FH-WT as well as its correlation to survival outcome and epidemiologic and clinical characteristics. Data of patients with FH-WT presenting to the National Cancer Institute, Egypt, were retrospectively analyzed. Paraffin blocks were tested for 1p and 16q LOH using polymorphic loci that span the minimal regions of LOH at this area. The study included 100 patients with a median age of 5 years. Thirty-nine patients (39%) showed LOH at 1p (n = 14), 16q (n = 13), or both (n = 12). LOH was most frequently encountered in patients above 10 years (5/5), advanced stages disease (80% of stage V and 50% of stages IV and III each). The 3-year overall survival (OS) and event-free survival (EFS) were significantly lower in patients with double LOH (75% and 50%, respectively), followed by 16q (92% and 54%), in comparison with 1p (93% each) and negative LOH (97% and 100%) cases, respectively (p = 0.001). Combined LOH (1p+16q), followed by 16q LOH alone, was predictive of poorer outcome and was associated with lower OS and EFS in patients with FH-WT. Our results showed a higher-risk disease that would suggest the need for an intensified upfront therapy in this group of patients.

Prognostic impact of chromosomal aberrations in Ewing tumours

Although greater than 50% of Ewing tumours contain non-random cytogenetic aberrations in addition to the pathognomonic 22q12 rearrangements, little is known about their prognostic significance. To address this question, tumour samples from 134 Ewing tumour patients were analysed using a combination of classical cytogenetics, comparative genomic and fluorescence in situ hybridisation. The evaluation of the compiled data revealed that gain of chromosome 8 occurred in 52% of Ewing tumours but was not a predictive factor for outcome. Gain of 1q was associated with adverse overall survival and event-free survival in all patients, irrespective of whether the tumour was localised or disseminated (overall survival: P=0.002 and P=0.029; event-free survival: P=0.018 and P=0.010). Loss of 16q was a significant predictive factor for adverse overall survival in all patients (P=0.008) and was associated with disseminated disease at diagnosis (P=0.039). Gain of chromosome 12 was associated with adverse event-free survival (P=0.009) in patients with localised disease. These results indicate that in addition to a 22q12 rearrangement confirmation in Ewing tumours it is important to assess the copy number of 1q and 16q to identify patients with a higher probability of adverse outcome.

Chromosome band 16q24 is frequently deleted in human gastric cancer

We have analysed the loss of heterozygosity (LOH) on chromosome bands 16q22-q24 in 24 primary gastric cancer tissues and found three regions of frequent allelic loss (16q22, 16q24.1-q24.3 and 16q24.3). The region for the most frequent allelic loss (63%) was in 16q24.1-q24.3. LOH of this region had no relationship with histological subtype, but a significant association between LOH and microscopic lymphangial invasion was observed. Although not significant, vascular and gastric wall invasions are also associated with LOH. The region includes the locus for the H-cadherin gene. Therefore we examined the genetic and epigenetic alterations of this gene. Markedly reduced expression was observed in gastric cancer cell lines compared with that of normal gastric mucosa. However, no mutation was found in this gene in any of the gastric cancer tissues or the gastric cancer cell lines. Furthermore, we analysed the methylation status of the 5'-flanking region of the gene, but no significant association was found. We suggest that some other tumour suppressor gene(s) in 16q24.1-q24.3 may be responsible for gastric carcinogenesis.

Three independently deleted regions at chromosome arm 16q in human prostate cancer: allelic loss at 16q24.1-q24.2 is associated with aggressive behaviour of the disease, recurrent growth, poor differentiation of the tumour and poor prognosis for the patient

Loss of heterozygosity at chromosome arm 16q is a frequent event in human prostate cancer. In this study, loss of heterozygosity at 16q was studied in 44 prostate cancer patients exhibiting various clinical features. Fifteen polymorphic polymerase chain reaction (PCR) markers were used to identify the separately deleted areas and the findings were compared with clinicopathological variables and 5-year survival of the patients. The results indicated that there are at least three independently deleted regions at 16q. Allelic losses at the central and distal areas were associated significantly with aggressive behaviour of the disease (16q24.1-q24.2, P < 0.01, and 16q24.3-qter, P < 0.05), and the central area of deletion was further significantly associated with poorly differentiated tumour cells (P < 0.05) and with recurrent (P < 0.01) growth of the tumour. During the follow-up period, 28% of the patients initially with M0 disease developed distant metastases. Of the patients showing allelic loss at 16q24.1-q24.2, distant metastasis were found in 45% during the 5-year follow-up period, and 31% of the patients showing loss at 16q21.1 also developed distant metastases. After the 5-year follow-up period, 14 (32%) of the patients remained alive, whereas 19 (43%) had died because of their prostate cancer. The overall survival rate of the patients showing allelic loss at 16q21.1 or 16q24.1-q24.2 was significantly lower than that of the patients with retained heterozygosity.