The human 16p11.2 chromosomal region is rich in segmental duplications which mediate the formation of recurrent CNVs. CNVs affecting the 16p11.2 region are associated with an increased risk for developing neuropsychiatric disorders, including autism spectrum disorder (ASD), schizophrenia, and intellectual disability (ID), as well as abnormal body weight and head circumference and dysmorphic features, with marked phenotypic variability and reduced penetrance. CNVs affecting the 16p11.2 region mainly affect a distal interval of ~220 Kb, between Breakpoints 2 and 3 (BP2–BP3), and a proximal interval of ~593 Kb (BP4–BP5). Here, we report on 15 patients with recurrent 16p11.2 rearrangements that were identified among a cohort of 1600 patients (0.9%) with neurodevelopmental disorders. A total of 13 deletions and two duplications were identified, of which eight deletions included the proximal 16p11.2 region (BP4–BP5) and five included the distal 16p11.2 region (BP2–BP3). Of the two duplications that were identified, one affected the proximal and one the distal 16p11.2 region; however, both patients had additional CNVs contributing to phenotypic severity. The features observed and their severity varied greatly, even between patients within the same family. This article aims to further delineate the clinical spectrum of patients with 16p11.2 recurrent rearrangements in order to aid the counselling of patients and their families.

Chromosomal microarray analysis (CMA) is considered a first-tier test for patients with developmental disabilities and congenital anomalies and is also routinely applied in prenatal diagnosis. The current consensus size cut-off for reporting copy number variants (CNVs) in the prenatal setting ranges from 200 Kb to 400 Kb, with the intention of minimizing the impact of variants of uncertain significance (VUS). Very limited data are currently available on the application of higher resolution platforms prenatally. The aim of this study is to investigate the feasibility and impact of applying high-resolution CMA in the prenatal setting. To that end, we report on the outcomes of applying CMA with a size cut-off of 20 Kb in 250 prenatal samples and discuss the findings and diagnostic yield and also provide follow-up for cases with variants of uncertain significance. Overall, 19.6% (49) showed one or more chromosomal abnormalities, with the findings classified as Pathogenic (P) or Likely Pathogenic (LP) in 15.6% and as VUS in 4%. When excluding the cases with known familial aberrations, the diagnostic yield was 12%. The smallest aberration detected was a 32 Kb duplication of the 16p11.2 region. In conclusion, this study demonstrates that prenatal diagnosis with a high-resolution aCGH platform can reliably detect smaller CNVs that are often associated with neurodevelopmental phenotypes while providing an increased diagnostic yield, regardless of the indication for testing, with only a marginal increase in the VUS incidence. Thus, it can be an important tool in the prenatal setting.

Alport syndrome (AS) is a hereditary glomerulopathy due to pathogenic variants in COL4A3, COL4A4, and COL4A5. Treatment with Renin–Angiotensin–Aldosterone System (RAAS) inhibitors can delay progression to end stage renal disease (ESRD). From 2018 until today, we performed Whole Exome Sequencing (WES) in 19 patients with AS phenotype with or without positive family history. Fourteen of these patients were children. Genetic testing was extended to family members at risk. All patients received a genetic diagnosis of AS: five X-linked AS (XLAS) males, five X-linked AS (XLAS) females, six autosomal dominant AS (ADAS), and one autosomal recessive AS (ARAS). After cascade screening four XLAS males and eight XLAS females, six ADAS and three ARAS heterozygotes were added to our initial results. Fifteen patients were eligible to start treatment with RAAS inhibitors after their diagnosis. All XLAS female patients, ARAS heterozygotes, and ADAS have been advised to be followed up, so that therapeutic intervention can begin in the presence of microalbuminuria. Genetic diagnosis of AS ensures early therapeutic intervention and appropriate follow up to delay progression to chronic kidney disease, especially in thet pediatric population.

This is a case with multiple chromosomal aberrations which are likely etiological for the observed psychiatric phenotype consisting of attention deficit hyperactivity and conduct disorders. We report on an 11 year-old boy, admitted to the pediatric hospital for behavioral difficulties and a delayed neurodevelopmental trajectory. A cytogenetic analysis and high-resolution microarray comparative genomic hybridization (CGH) analysis was performed. The cytogenetic analysis revealed 47,XYY syndrome, while CGH analysis revealed an additional duplication and two deletions. The 7q11.23 duplication is associated with speech and language delay and behavioral symptoms, a 20q13.33 deletion is associated with autism and early onset schizophrenia and the 11p15.5 microdeletion is associated with developmental delay, autism, and epilepsy. The patient underwent a psychiatric history, physical examination, laboratory testing, and a detailed cognitive, psychiatric, and occupational therapy evaluation which are reported here in detail. In the case of psychiatric patients presenting with complex genetic aberrations and additional psychosocial problems, traditional psychiatric and psychological approaches can lead to significantly improved functioning. Genetic diagnostic testing can be highly informative in the diagnostic process and may be applied to patients in psychiatry in case of complex clinical presentations.

X-linked myotubular myopathy (XLMTM) is a rare inherited neuromuscular disorder associated with mutations in the MTM1 gene on the Xq28 region. We report a severely affected girl with XLMTM, caused by maternally inherited 661 kb Xq28 microduplication identified by chromosomal microarray analysis and confirmed also on DNA from muscle biopsy with a custom-designed X-chromosome-specific microarray. X-inactivation analysis revealed a skewed inactivation pattern on the proband's muscle biopsy. Muscle biopsy histopathology was indicative of increased variability in fiber diameter, marked and diffuse endomysial proliferation of adipose and connective tissues, as well as predominance of type 1 fibers.