The first case report of distal 16p12.1p11.2 trisomy and proximal 16p11.2 tetrasomy inherited from both parents

Recurrent copy number variants in the chromosomal region 16p11.2 are among the most frequent genetic causes of neurodevelopmental disorders. The increasing prevalence of brain structural anomalies is also associated with 16p11.2 deletions and duplications. We report on a four-year-old boy with microcephaly, trigonocephaly, and dysmorphic features. The patient also exhibited motor delay and autism spectrum disorder. Microarray analysis showed a single-copy gain of a 1.187 kb segment in the 16p12.1p11.2 region and a two-copy gain of a 525 kb segment in the 16p11.2 region. Parental analysis revealed a 1.7 Mb duplication at the 16p12.1p11.2 (BP1-BP5 region) in the father and a 525 kb duplication in the 16p11.2 region (BP4-BP5) in the mother. The patient inherited the entire abnormality from each parent and, as a result, presented with partial trisomy of the 16p12.1p11.2 region and partial tetrasomy of the 16p11.2 region. The MLPA P343 Autism-1 Probemix was used to verify the copy number gains in the 16p11.2 region detected by chromosomal microarray analysis. Double duplications are very rare chromosomal rearrangements. The phenotype for distal 16p12.1p11.2 trisomy (BP1-BP3) and proximal 16p11.2 (BP4-BP5) tetrasomy is unknown. To our knowledge, this is the first patient described in the literature who inherited 16p11.2 duplications from both parents.

Clinical relevance of the TECTA c.6183G>T variant identified in a family with autosomal dominant hearing loss: a case report

Missense variants in the α-tectorin gene (TECTA) cause autosomal dominant (DFNA8/A12) non-syndromic hearing loss (ADNSHL) and account for a considerable number of ADNSHL cases. According to genotype-phenotype correlation studies, missense variants in the zona pellucida (ZP) domain of α-tectorin predominantly cause mid-frequency HL. Here, we report on clinical exome sequencing results in a large family with early-onset, sensorineural, moderate-to-severe mid-frequency HL. We identified one heterozygous c.6183G>T variant near the ZP domain of TECTA segregating in five family members. This variant was previously reported as a variant of uncertain significance in a family with ADNSHL. On the basis of specific segregation in the currently studied family and the general guidelines of the American College of Medical Genetics and Genomics, we argue that the TECTA c.6183G>T variant should be considered a likely pathogenic cause of ADNSHL. This report adds to the knowledge on the rare c.6183G>T missense variant, which affects the immediate vicinity of the ZP domain in TECTA. Our findings highlight the importance of clinical evaluation in patients with familial HL and of studying family segregation when assessing the pathogenicity of a variant.

Trends in the treatment of undescended testes: a pediatric tertiary care center experience from Croatia

OBJECTIVE

Undescended testes (UDT) is the most common anomaly of the male genitourinary tract. The guidelines suggest that orchidopexy in congenitally UDT should be performed between 6 months and 18 months of age, while in acquired UDT, orchidopexy should be performed before puberty. Delay in treatment increases the risk of cancer and infertility. The main aim of this study was to determine whether we meet international standards in the treatment of UDT.

METHODS

The present study included all boys who underwent orchidopexy either due to congenital or acquired UDT in 2019 (from January 1 to December 31). For each group, laterality, location, associated anomalies, premature birth and in how many cases ultrasound was applied were determined. Additionally, for each group, the types of surgery, the number of necessary reoperations, and in how many cases atrophy occurred were determined. Finally, ages of referral, of clinical examination, and of orchidopexy were determined.

RESULTS

During this period, 198 patients with 263 UDT underwent orchidopexy. The median time of orchidopexy for the congenital group was 30 months, while that for the acquired group was 99 months. In the congenital group up to 18 months of age, orchidopexy was performed in 16 (16%) boys, while in the acquired group up to 13 years of age, orchidopexy was performed in 95 (96.94%) boys.

CONCLUSION

Given the well-known risks of late treatment of UDT, orchidopexy needs to be performed much earlier, especially in the congenital group.

Chromosomal microarray in clinical diagnosis: a study of 337 patients with congenital anomalies and developmental delays or intellectual disability

Aim

To determine the diagnostic yield and criteria that could help to classify and interpret the copy number variations (CNVs) detected by chromosomal microarray (CMA) technique in patients with congenital and developmental abnormalities including dysmorphia, developmental delay (DD) or intellectual disability (ID), autism spectrum disorders (ASD) and congenital anomalies (CA).

Method

CMA analysis was performed in 337 patients with DD/ID with or without dysmorphism, ASD, and/or CA. In 30 of 337 patients, chromosomal imbalances had previously been detected by classical cytogenetic and molecular cytogenetic methods.

Results

In 73 of 337 patients, clinically relevant variants were detected and better characterized. Most of them were >1 Mb. Variants of unknown clinical significance (VOUS) were discovered in 35 patients. The most common VOUS size category was <300 kb (40.5%). Deletions and de novo imbalances were more frequent in pathogenic CNV than in VOUS category. CMA had a high diagnostic yield of 43/307, excluding patients previously detected by other methods.

Conclusion

CMA was valuable in establishing the diagnosis in a high proportion of patients. Criteria for classification and interpretation of CNVs include CNV size and type, mode of inheritance, and genotype-phenotype correlation. Agilent ISCA v2 Human Genome 8x60 K oligonucleotide microarray format proved to be reasonable resolution for clinical use, particularly in the regions that are recommended by the International Standard Cytogenomic Array (ISCA) Consortium and associated with well-established syndromes.

Prevalence of the 35delG Mutation in theGJB2Gene of Patients with Nonsyndromic Hearing Loss from Croatia

The aim of this study was to investigate the allelic frequency of 35delG mutation in patients with recessive, nonsyndromic hearing loss (NSHL) compared to normal hearing individuals in the Croatian population. For this purpose, we analyzed 27 unrelated individuals with nonsyndromic hearing loss and 342 healthy individuals. The method we used is based on the principle of polymerase chain reaction (PCR)-mediated, site-directed mutagenesis, followed by a BsiYI digestion. Among patients with NSHL, the 35delG mutation was found on 51.85% alleles. Carrier frequency among healthy control individuals was 1 in 68.4 (1.5%). The patients, found to be wild-type, either in heterozygous or homozygous form, were further tested by direct sequencing. Among them, two different mutations were observed, W24X and 313del14. Relatively high prevalence of 35delG mutation among patients with NSHL indicate that it is an important cause of NSHL in Croatia. Early diagnosis by identification of the 35delG mutation would greatly improve genetic counseling, as well as treatment and management of deafness in Croatia.