Exome Sequencing Reveals Novel Variants and Expands the Genetic Landscape for Congenital Microcephaly.

Congenital microcephaly causes smaller than average head circumference relative to age, sex and ethnicity and is most usually associated with a variety of neurodevelopmental disorders. The underlying etiology is highly heterogeneous and can be either environmental or genetic. Disruption of any one of multiple biological processes, such as those underlying neurogenesis, cell cycle and division, DNA repair or transcription regulation, can result in microcephaly. This etiological heterogeneity manifests in a clinical variability and presents a major diagnostic and therapeutic challenge, leaving an unacceptably large proportion of over half of microcephaly patients without molecular diagnosis. To elucidate the clinical and genetic landscapes of congenital microcephaly, we sequenced the exomes of 191 clinically diagnosed patients with microcephaly as one of the features. We established a molecular basis for microcephaly in 71 patients (37%), and detected novel variants in five high confidence candidate genes previously unassociated with this condition. We report a large number of patients with mutations in tubulin-related genes in our cohort as well as higher incidence of pathogenic mutations in MCPH genes. Our study expands the phenotypic and genetic landscape of microcephaly, facilitating differential clinical diagnoses for disorders associated with most commonly disrupted genes in our cohort.

Single Nucleotide Polymorphisms of Interleukins and Toll-like Receptors and Neuroimaging Results in Newborns with Congenital HCMV Infection.

Congenital cytomegalovirus infection (cCMV) is the most common intrauterine infection with central nervous system (CNS) involvement. There is limited data on the associations between Single Nucleotide Polymorphisms (SNPs) in genes involving the first-line defense mechanism and the risk of CNS damage during cCMV. We investigated the associations between neuroimaging findings and SNPs in genes encoding the following cytokines and cytokine receptors in 92 infants with cCMV: interleukins (IL1B rs16944, IL12B rs3212227, IL28B rs12979860), C-C motif chemokine ligand 2 (CCL2 rs1024611), dendritic cell-specific intercellular adhesion grabbing non-integrin (DC-SIGN rs735240), Toll-like receptors (TLR2 rs5743708, TLR4 rs4986791, TLR9 rs352140). The SNP of IL1B rs16944 (G/A) was associated with a reduced risk of ventriculomegaly on MRI (OR = 0.46, 95% CI, 0.22-0.95; p = 0.03) and cUS (OR = 0.38, 95% CI, 0.0-0.93; p = 0.034). Infants carrying heterozygous (T/C) genotype at IL28B rs12979860 had an increased risk of cystic lesions on cUS (OR = 3.31, 95% CI, 1.37-8.01; p = 0.0064) and MRI (OR = 4.97, 95% CI, 1.84-13.43; p = 0.001), and an increased risk of ventriculomegaly on MRI (OR = 2.46, 95% CI, 1.03-5.90; p = 0.04). No other associations between genotyped SNPs and neuroimaging results were found. This is the first study demonstrating new associations between SNPs of IL1B and IL28B and abnormal neuroimaging in infants with cCMV.

The Limitations of Cytomegalovirus DNA Detection in Cerebrospinal Fluid of Newborn Infants With Congenital CMV Infection: A Tertiary Care Neonatal Center Experience.

BACKGROUND: Congenital cytomegalovirus (cCMV) infection of the central nervous system (CNS) can cause ventriculomegaly, gliosis, calcifications and cortical defects. Detection of CMV DNA in cerebrospinal fluid by PCR (CSF-CMV-PCR) is a marker of CNS involvement. OBJECTIVE: To evaluate a diagnostic value of the positive CSF-CMV-PCR in cCMV. METHODS: Analysis of clinical, laboratory, neuroimaging and single-nucleotide polymorphisms (SNPs) data according to the results of CSF-CMV-PCR were performed in infants with cCMV. RESULTS: A total of 168 infants were included; 145 (86.3%) had negative and 23 (13.7%) had positive CSF-CMV-PCR results. Associations between the positive CSF-CMV-PCR results and prematurity (odds ratio [OR] = 3.24; 95% confidence interval [CI]: 1.30-8.07), microcephaly (OR = 5.67; 95% CI: 2.08-15.41), seizures (OR = 4.15; 95% CI: 1.10-15.67), sensorineural hearing loss (OR = 6.6; 95% CI: 2.49-17.46), splenomegaly (OR = 8.13; 95% CI: 3.12-21.16), hepatitis (OR = 10.51; 95% CI: 3.31-33.35), petechiae (OR = 10.21; 95% CI: 3.78-27.57) and heterozygous T/C genotype at TLR4rs4986791 (OR = 7.88; 95% CI: 1.55-40.12) were observed. When using a multivariate logistic regression analysis, only the presence of severe sensorineural hearing loss (OR = 7.18; 95% CI: 1.75-29.34, P = 0.006), cystic lesions on MRI (OR 5.29; 95% CI: 1.31-21.36, P = 0.02), and calcifications on MRI (OR = 7.19; 95% CI: 1.67-30.97, P = 0.008) remained as the significant independent predictors of the positive CSF-CMV-PCR results. CONCLUSIONS: The detection of CMV DNA in CSF is associated with a higher rate of CNS damage including abnormal MRI neuroimaging and severe hearing loss. Therefore, detection of CMV DNA in CSF may be considered as a marker of severe CNS injury in cCMV infection. However, the very low prevalence of the positive CSF-CMV-PCR results, even in infants with proven CNS involvement, may imply its limited role in clinical practice.

Association between single nucleotide polymorphisms and viral load in congenital cytomegalovirus infection.

BACKGROUND: There are limited data on factors that determine viral load (VL) in congenital cytomegalovirus (cCMV) infection. Single nucleotide polymorphisms (SNPs) might influence individual host response to infection. This study aimed to investigate the association between SNPs in genes encoding cytokines or cytokine receptors and VL in newborns with cCMV. MATERIAL AND METHODS: Eight polymorphisms (IL1B rs16944, IL12B rs3212227, IL28B rs12979860, CCL2 rs1024611, DC-SIGN rs735240, TLR2 rs5743708, TLR4 rs4986791 and TLR9 rs352140) were analyzed in study population of 233 newborns, including 92 cCMV-infected newborns (73 symptomatic and 19 asymptomatic) by TaqMan SNP Predesigned Genotyping Assays. The association analysis was performed using SNPStats software and STATISTICA10. RESULTS: The association between IL12B polymorphism and viruria was observed (p = 0.029). In multiple comparison tests, heterozygous T/G genotype of IL12B was associated with higher viruria than T/T genotype (p = 0.041) in cCMV-infected newborns. In allele analysis, T allele of IL12B was associated with higher viremia (p = 0.037) in symptomatic newborns. We observed higher VL in symptomatic newborns in comparison to asymptomatic (median viremia: 1.7 × 104 copies/mL vs. 2.0 × 103 copies/mL (p = 0.002), median viruria: 1.0 × 107 copies/mL versus 6.9 × 105 copies/mL (p = 0.001), respectively). CONCLUSIONS: IL12B rs3212227 was associated with VL in cCMV. Symptomatic newborns had significantly higher viremia and viruria. The role of SNPs in pathogenesis of cCMV warrants further investigations.

Antiviral treatment in congenital HCMV infection: The six-year experience of a single neonatal center in Poland.

BACKGROUND: Antiviral treatment is recommended for symptomatic newborns with congenital cytomegalovirus infection (cCMV). OBJECTIVES: To compare 2 treatment methods in neonates with cCMV - ganciclovir-based therapy (intravenous ganciclovir (GCV) or sequential GCV + valganciclovir (VGCV) therapy) with oral VGCV-based therapy - in Polish neonates. MATERIAL AND METHODS: A total of 98 symptomatic infants with cCMV (positive HCMV DNA in urine ≤21st day of life) hospitalized in the neonatal intensive care unit (NICU) between 2012 and 2017 were enrolled. Clinical characteristics, the viral load in blood and urine, hematological and biochemical tests, neuroimaging results, and the length of hospitalization were compared between the study groups at baseline and at the 2nd hospitalization. RESULTS: In 2012, GCV was used in 57% of the cases, sequential therapy in 33% and VGCV in 10%. In 2017, VGCV monotherapy was used in 83% of the infants treated. Valganciclovir treatment allowed the length of hospitalization to be shortened over 2.5 times during the six-year observation period. Infants treated intravenously had lower birth weights and head circumferences, and more frequently presented splenomegaly, petechiae, thrombocytopenia, and hepatitis. The baseline viral load in the blood and urine were similar in both groups, but at follow-up visits 4-6 weeks later, a viral load about 70 times lower was observed in the blood of the VGCV-based group (1029 viral copies/mL compared to 72,188 viral copies/mL in the GCV-based group; p = 0.04). The prevalence of neutropenia was similar in both groups at the follow-up visits. CONCLUSIONS: Valganciclovir became the first line of antiviral therapy in cCMV in the study population. Compared to GCV-based therapy, VGCV monotherapy allowed shorter hospital stays and reduced the viral load in blood due to continuing treatment at home. Valganciclovir monotherapy did not provoke more side effects such as neutropenia. Intravenous GCV is still suitable for patients with severe disseminated disease, born prematurely, with low birth weights, or not tolerating enteral feeding. In those infants, the sequential therapy seems to be optimal.

Association between single nucleotide polymorphisms (SNPs) of IL1, IL12, IL28 and TLR4 and symptoms of congenital cytomegalovirus infection.

Congenital cytomegalovirus (cCMV) infection is the most common intrauterine infection. A non-specific immune response is the first line of host defense mechanism against human cytomegalovirus (HCMV). There is limited data on associations between Single Nucleotide Polymorphisms (SNPs) in genes involving innate immunity and the risk and clinical manifestation of cCMV infection. The aim of the study was to investigate association between selected SNPs in genes encoding cytokines and cytokine receptors, and predisposition to cCMV infection including symptomatic course of disease and symptoms. A panel of eight SNPs: IL1B rs16944, IL12B rs3212227, IL28B rs12979860, CCL2 rs1024611, DC-SIGN rs735240, TLR2 rs5743708, TLR4 rs4986791, TLR9 rs352140 was analyzed in 233 infants (92 cCMV-infected and 141 healthy controls). Associations between genotyped SNPs and predisposition to cCMV infection and symptoms were analyzed. The association analysis was performed using SNPStats software. No statistically significant association was found between any genotyped SNPs and predisposition to cCMV infection and symptomatic course of disease. In relation to particular symptoms, polymorphism of IL12B rs3212227 was linked to decreased risk of prematurity (OR = 0.37;95%CI,0.14-0.98;p = 0.025), while polymorphism of IL1B rs16944 was linked to reduced risk of splenomegaly (OR = 0.36;95%CI,0.14-0.98; p = 0.034) in infants with cCMV infection. An increased risk of thrombocytopenia was associated with IL28B rs12979860 polymorphism (OR = 2.55;95%CI,1.03-6.32;p = 0.042), while hepatitis was associated with SNP of TLR4rs4986791 (OR = 7.80;95%CI,1.49-40,81; p = 0.024). This is the first study to demonstrate four new associations between SNPs in selected genes (IL1B, IL12B, IL28B, TLR4) and particular symptoms in cCMV disease. Further studies on the role of SNPs in the pathogenesis of cCMV infection and incorporation of selected SNPs in the clinical practice might be considered in the future.