Rapid and efficient diagnostics is crucial for newborns with congenital heart defects (CHD) in intensive care unit (ICU) but is often challenging. Given that genetic factors play a role in 20–30% cases of CHD, it is likely that genetic tests could improve both its speed and efficiency. We aimed to analyze the utility of rapid and cost-effective multiplex ligation dependent probe amplification analysis (MLPA) for chromosomal analysis in newborns with critical CHD. One hundred consecutive newborns admitted with critical CHD to the ICU were included in the study. Those with normal MLPA findings were further tested by chromosomal microarray and clinical exome sequencing. Overall, pathogenic/likely pathogenic variants were determined in ten (10%) newborns by MLPA, three (3%) by chromosomal microarray, and three (3%) by clinical exome sequencing. The most common variant detected was deletion of 22q11.2 region. Conclusion: MLPA is fast and cost-effective analysis that could be used as the first-tier test in newborns with critical CHD admitted to the ICU.

Clinical exome sequencing is currently being used in diagnostics of various genetic disorders, but studies supporting its application in clinical setting are scarce. The aim of this study was to establish diagnostic and clinical utility of clinical exome sequencing in patients with moderate and severe global developmental delay/intellectual disability. Clinical diagnosis was made in 49 of 88 investigated patients, with overall diagnostic yield of 55.7%. Molecular findings are characterized in detail, including the impact of newly made diagnosis on clinical management. Several previously unreported genotype-phenotype correlations and 33 novel variants are described. Genetic and clinical data were shared through publicly available database. In conclusion, clinical exome sequencing allows identification of causative variants in a significant proportion of patients in investigated clinical subgroup. Compared to whole exome sequencing, it shows similar diagnostic and clinical utility with reduced costs, which could be of particular importance for institutions with limited resources.

Primary microcephalies (MCPH) are characterized by microcephaly (HC -2 SD at birth) in the absence of visceral malformations. To date, less than 20 genes have been associated with MCHP, several of which are involved in the formation and function of the centrosome. Here, we report a novel missense variant in the TUBGCP5 gene in a patient with primary microcephaly and mild developmental delay. The TUBCGP5 gene (tubulin gamma complex associated protein 5) is a paralog of TUBGCP4 and TUBGCP6, both of which are known MCPH associated genes, and like its paralogs, is involved in centrosome formation. Furthermore, the TUBGCP5 gene is located in the 15q11.2 BP1-BP2 microdeletion Burnside-Butler susceptibility locus that is part of the larger Prader-Willi/Angelman region. Common clinical features of the 15q11.2 BP1-BP2 microdeletion include general developmental and neurodevelopmental delay which may occasionally be accompanied by yet unexplained microcephaly. In our patient, the TUBGCP5:c.2180T > G, p.Phe727Cys missense variant was identified in compound heterozygous state with 15q11.2 BP1-BP2 microdeletion using whole exome sequencing, after the initial analyses of known MCPH genes failed to identify a conclusively causative variant. The identified variant is rare and highly conserved, as shown by population allele frequency data from ExAC and GnomAD, as well as comparisons with all other vertebrates. Based on this evidence we suggest that the identified TUBGCP5 variant in our patient may thus represent a novel cause of MCPH with mild developmental delay and may play a role in occurrence of microcephaly in 15q11.2 microdeletion carriers. Further studies are required to further clarify the causality and penetrance of TBGCP5 variants in primary microcephaly.