Exome sequencing reveals genetic heterogeneity and clinically actionable findings in children with cerebral palsy.

Cerebral palsy (CP) is the most common motor disability in children. To ascertain the role of major genetic variants in the etiology of CP, we conducted exome sequencing on a large-scale cohort with clinical manifestations of CP. The study cohort comprised 505 girls and 1,073 boys. Utilizing the current gold standard in genetic diagnostics, 387 of these 1,578 children (24.5%) received genetic diagnoses. We identified 412 pathogenic and likely pathogenic (P/LP) variants across 219 genes associated with neurodevelopmental disorders, and 59 P/LP copy number variants. The genetic diagnostic rate of children with CP labeled at birth with perinatal asphyxia was higher than the rate in children without asphyxia (P = 0.0033). Also, 33 children with CP manifestations (8.5%, 33 of 387) had findings that were clinically actionable. These results highlight the need for early genetic testing in children with CP, especially those with risk factors like perinatal asphyxia, to enable evidence-based medical decision-making.

Genetic variants in the HLA region contribute to the risk of cerebral palsy.

Cerebral palsy (CP) is the most common physical disability in childhood, and genetic factors play an important role in its pathogenesis. However, the genetic contributions remain incompletely elucidated. Here, we conducted a two-stage association study between 1090 CP cases and 1100 healthy controls after whole exome sequencing. The human leukocyte antigen (HLA) allelic predispositions were further analyzed in overall CP and subgroups using multivariate logistic regression. We found a strong signal in the HLA region on chromosome 6, where rs3131787 harbored the most significant association with CP (P = 2.05 × 10-14, OR = 2.22). In comparison to controls, the carrier frequencies of HLA-B*13:02 were significantly higher in children with CP (9.82 % in control vs 19.27 % in CP, P = 1.03 × 10-4, OR = 2.17). Furthermore, the effect of HLA-B*13:02 on increasing the risk of CP mainly existed in cryptogenic CP without exposure to premature birth, low birth weight, birth asphyxia, or periventricular leukomalacia. This study indicated a strong association of HLA variants with CP, which implied that immune dysregulation resulting from immunogenetic variants might underlie the pathogenesis of CP. Our findings provide genetic evidence that an immunomodulator may serve as a promising therapeutic intervention for patients with CP by reinstating the neuroinflammation hemostasis.

An association study of IL2RA polymorphisms with cerebral palsy in a Chinese population.

BACKGROUND: Cerebral palsy (CP), the most common physical disability of childhood, is a nonprogressive movement disorder syndrome. Eighty percent of cases are considered idiopathic without a clear cause. Evidence has shown that cytokine abnormalities are widely thought to contribute to CP. METHODS: An association between 6 SNPs (rs12244380, rs2025345, rs12722561, rs4749926, rs2104286 and rs706778) in IL2RA (interleukin 2 receptor subunit alpha) and CP was investigated using a case-control method based on 782 CP cases and 778 controls. The allele, genotype and haplotype frequencies of SNPs were assessed using the SHEsis program. Subgroup analyses based on complications and clinical subtypes were also conducted. RESULTS: Globally, no differences in genotype or allele frequencies for any SNPs remained significant after Bonferroni correction between patients and controls, except rs706778, which deviated from Hardy-Weinberg equilibrium and was excluded from further analyses. However, subgroup analysis revealed a significant association of rs2025345 with spastic tetraplegia (P genotype = 0.048 after correction) and rs12722561 with CP accompanied by global developmental delay (P allele = 0.045 after correction), even after Bonferroni correction. CONCLUSIONS: These findings indicated that genetic variations in IL2RA are significantly associated with CP susceptibility in the Chinese Han population, suggesting that IL2RA is likely involved in the pathogenesis of CP. Further investigation with a larger sample size in a multiethnic population is needed to confirm the association.

The Association Study of IL-23R Polymorphisms With Cerebral Palsy in Chinese Population.

Background: Cerebral palsy (CP) is a syndrome of non-progressive motor dysfunction caused by early brain development injury. Recent evidence has shown that immunological abnormalities are associated with an increased risk of CP. Methods: We recruited 782 children with CP as the case group and 770 healthy children as the control group. The association between IL-23R single nucleotide polymorphisms (SNPs; namely, rs10889657, rs6682925, rs1884444, rs17375018, rs1004819, rs11805303, and rs10889677) and CP was studied by using a case-control method and SHEsis online software. Subgroup analysis based on complications and clinical subtypes was also carried out. Results: There were differences in the allele and genotype frequencies between CP cases and controls at the rs11805303 and rs10889677 SNPs (Pallele = 0.014 and 0.048, respectively; Pgenotype = 0.023 and 0.008, respectively), and the difference in genotype frequency of rs10889677 remained significant after Bonferroni correction (Pgenotype = 0.048). Subgroup analysis revealed a more significant association of rs10889677 with CP accompanied by global developmental delay (Pgenotype = 0.024 after correction) and neonatal encephalopathy (Pgenotype = 0.024 after correction). Conclusion: The present results showed a significant association between IL-23R and CP, suggesting that IL-23R may play a potential role in CP pathogenesis.

Mutations disrupting neuritogenesis genes confer risk for cerebral palsy.

In addition to commonly associated environmental factors, genomic factors may cause cerebral palsy. We performed whole-exome sequencing of 250 parent-offspring trios, and observed enrichment of damaging de novo mutations in cerebral palsy cases. Eight genes had multiple damaging de novo mutations; of these, two (TUBA1A and CTNNB1) met genome-wide significance. We identified two novel monogenic etiologies, FBXO31 and RHOB, and showed that the RHOB mutation enhances active-state Rho effector binding while the FBXO31 mutation diminishes cyclin D levels. Candidate cerebral palsy risk genes overlapped with neurodevelopmental disorder genes. Network analyses identified enrichment of Rho GTPase, extracellular matrix, focal adhesion and cytoskeleton pathways. Cerebral palsy risk genes in enriched pathways were shown to regulate neuromotor function in a Drosophila reverse genetics screen. We estimate that 14% of cases could be attributed to an excess of damaging de novo or recessive variants. These findings provide evidence for genetically mediated dysregulation of early neuronal connectivity in cerebral palsy.

Autophagy-Related Gene 7 Polymorphisms and Cerebral Palsy in Chinese Infants.

Cerebral palsy (CP) is a group of non-progressive motor impairment syndromes that are secondary to brain injury in the early stages of brain development. Numerous etiologies and risk factors of CP have been reported, and genetic contributions have recently been identified. Autophagy has an important role in brain development and pathological process, and autophagy-related gene 7 (ATG7) is essential for autophagosome biogenesis. The purpose of this study was to investigate the genetic association between ATG7 gene single nucleotide polymorphisms (SNPs) and CP in Han Chinese children. Six SNPs (rs346078, rs1470612, rs11706903, rs2606750, rs2594972, and rs4684787) were genotyped in 715 CP patients and 658 healthy controls using the MassArray platform. Plasma ATG7 protein was determined in 73 CP patients and 79 healthy controls. The differences in the allele and genotype frequencies of the rs1470612 and rs2594972 SNPs were determined between the CP patients and controls (p allele = 0.02 and 0.0004, p genotype = 0.044 and 0.0012, respectively). Subgroup analysis revealed a more significant association of rs1470612 (p allele = 0.004, p genotype = 0.0036) and rs2594972 (p allele = 0.0004, p genotype < 0.0001) with male CP, and more significant differences in allele and genotype frequencies were also noticed between CP patients with spastic diplegia and controls for rs1470612 (p allele = 0.0024, p genotype = 0.008) and rs2594972 (p allele < 0.0001, p genotype = 0.006). The plasma ATG7 level was higher in CP patients compared to the controls (10.58 ± 0.85 vs. 8.18 ± 0.64 pg/mL, p = 0.024). The luciferase reporter gene assay showed that the T allele of rs2594972 SNP could significantly increase transcriptional activity of the ATG7 promoter compared to the C allele (p = 0.009). These findings suggest that an association exists between genetic variants of ATG7 and susceptibility to CP, which provides novel evidence for the role of ATG7 in CP and contributes to our understanding of the molecular mechanisms of this neurodevelopmental disorder.

Variants of the OLIG2 Gene are Associated with Cerebral Palsy in Chinese Han Infants with Hypoxic-Ischemic Encephalopathy.

Cerebral palsy (CP) is a leading cause of neurological disability among young children. Congenial and adverse perinatal clinical conditions, such as genetic factors, perinatal infection, and asphyxia, are risk factors for CP. Oligodendrocyte transcription factor (OLIG2) is a protein that is expressed in brain oligodendrocyte cells and is involved in neuron repair after brain injury. In this study, we employed a Chinese Han cohort of 763 CP infants and 738 healthy controls to study the association of OLIG2 gene polymorphisms with CP. We found marginal association of the SNP rs6517135 with CP (p = 0.044) at the genotype level, and the association was greatly strengthened when we focused on the subgroup of CP infants who suffered from hypoxic-ischemic encephalopathy (HIE) after birth, with p = 0.003 (OR = 0.558) at the allele level and p = 0.007 at the genotype level, indicating a risk-associated role of the T allele of the SNP rs6517135 under HIE conditions. The haplotype CTTG for rs6517135-rs1005573-rs6517137-rs9653711 in OLIG2 was also significantly associated with the occurrence of CP in infants with HIE (p = 0.01, OR = 0.521). Our results indicate that in the Han Chinese population, the polymorphisms of OLIG2 were associated with CP, especially in patients who had suffered HIE injury. This finding could be used to develop personalized care for infants with high susceptibility to CP.

A novel mutation in EYA1 in a Chinese family with Branchio-oto-renal syndrome.

BACKGROUND: Branchio-oto-renal (BOR) syndrome is a dominant autosomal disorder characterized by phenotypes such as hearing loss, branchial fistulae, preauricular pits, and renal abnormalities. EYA1, the human homolog of the Drosophila "eye absent" gene on chromosome 8q13.3, is recognized as one of the most important genes associated with BOR syndrome. METHODS: The proposita in this study was a 5-year-old Chinese girl with hearing loss, bilateral otitis media with effusion, microtia, facial hypoplasia, palatoschisis, and bilateral branchial cleft fistulae. The girl's family members, except two who were deceased, agreed to undergo clinical examination. We collected blood samples from 10 family members, including six who were affected by the syndrome. Genomic DNA was extracted and subjected to Sanger sequencing. A minigene assay was performed to confirm whether splicing signals were altered. In addition, we performed western blotting to determine alterations in protein levels of the wild-type and mutant gene. RESULTS: Clinical tests showed that some of the family members met the criteria for BOR syndrome. The affected members harbored a novel heterozygous nonsense variation in exon 11 of EYA1, whereas no unaffected member carried the mutation at this position. Functional experiments did not detect abnormal splicing at the RNA level; however, western blotting showed that the mutated protein was truncated. CONCLUSIONS: This study reports a novel mutation associated with BOR syndrome in a Chinese family. We highlight the usefulness of genetic testing in the diagnosis of BOR syndrome. Thus, we believe that this report would benefit clinicians in this field.

Association of NOS1 gene polymorphisms with cerebral palsy in a Han Chinese population: a case-control study.

BACKGROUND: Cerebral palsy (CP) is the leading cause of motor disability in children; however, its pathogenesis is unknown in most cases. Growing evidence suggests that Nitric oxide synthase 1 (NOS1) is involved in neural development and neurologic diseases. The purpose of this study was to determine whether genetic variants of NOS1 contribute to CP susceptibility in a Han Chinese population. METHODS: A case-control study involving 652 CP patients and 636 healthy controls was conducted. Six SNPs in the NOS1 gene (rs3782219, rs6490121, rs2293054, rs10774909, rs3741475, and rs2682826) were selected, and the MassARRAY typing technique was applied for genotyping. Data analysis was conducted using SHEsis online software, and multiple test corrections were performed using SNPSpD online software. RESULTS: There were no significant differences in genotype and allele frequencies between patients and controls for the SNPs except rs6490121, which deviated from Hardy-Weinberg equilibrium and was excluded from further analyses. Subgroup analysis revealed differences in genotype frequencies between the CP with neonatal encephalopathy group (CP + NE) and control group for rs10774909, rs3741475, and rs2682826 (after SNPSpD correction, p = 0.004, 0.012, and 0.002, respectively). The T allele of NOS1 SNP rs3782219 was negatively associated with spastic quadriplegia (OR = 0.742, 95% CI = 0.600-0.918, after SNPSpD correction, p = 0.023). There were no differences in allele or genotype frequencies between CP subgroups and controls for the other genetic polymorphisms. CONCLUSIONS: NOS1 is associated with CP + NE and spastic quadriplegia, suggesting that NOS1 is likely involved in the pathogenesis of CP and that it is a potential therapeutic target for treatment of cerebral injury.

Combined Analysis of Interleukin-10 Gene Polymorphisms and Protein Expression in Children With Cerebral Palsy.

BACKGROUND: Interleukin-10 (IL-10) is an important anti-inflammatory and immunosuppressive cytokine, and it has indispensable functions in both the onset and development of inflammatory disorders. The association between persistent inflammation and the development of cerebral palsy (CP) has attracted much attention. OBJECTIVE: The purpose of this study was to investigate whether IL-10 gene polymorphisms and plasma protein expression are associated with CP and to analyze the role of IL-10 in CP. METHODS: A total of 282 CP patients and 197 healthy controls were genotyped for IL-10 polymorphisms (rs1554286, rs1518111, rs3024490, rs1800871, and rs1800896). Among them, 95 CP patients and 93 healthy controls were selected for plasma IL-10 measurement. RESULTS: The differences in the rs3024490 (p = 0.033) and rs1800871 (p = 0.033) allele frequencies of IL-10 were determined between CP patients and controls. The frequencies of allele and genotype between CP patients with spastic tetraplegia and normal controls of IL-10 polymorphisms showed significant differences for rs1554286, rs151811, rs3024490, rs1800871, and rs1800896 (pallele = 0.015, 0.009, 0.006, 0.003, and 0.006, pgenotype = 0.039, 0.018, 0.027, 0.012, and 0.03, respectively). The plasma IL-10 protein level in CP patients was higher than normal controls (9.13 ± 0.77 vs. 6.73 ± 0.63 pg/ml, p = 0.017). IL-10 polymorphisms and protein association analysis showed that the TT genotype had higher plasma IL-10 protein levels compared to the GG + GT genotype at rs3024490 (11.14 ± 7.27 vs. 7.44 ± 6.95 pg/ml, p = 0.045, respectively) in CP cases. CONCLUSION: These findings provide an important contribution toward explaining the pleiotropic role of IL-10 in the complex etiology of CP.

A Variant of the Autophagy-Related 5 Gene Is Associated with Child Cerebral Palsy.

Cerebral palsy (CP) is a major cause of childhood disability in developed and developing countries, but the pathogenic mechanisms of CP development remain largely unknown. Autophagy is a highly conserved cellular self-digestion of damaged organelles and dysfunctional macromolecules. Growing evidence suggests that autophagy-related gene 5 (ATG5)-dependent autophagy is involved in neural development, neuronal differentiation, and neurological degenerative diseases. The aim of this study was to analyze ATG5 protein expression and gene polymorphisms in Chinese patients with CP and to evaluate the importance of ATG5 in the development of CP. Five polymorphisms from different regions of the ATG5 gene (rs510432, rs3804338, rs573775, rs2299863, and rs6568431) were analyzed in 715 CP patients and 658 controls using MassARRAY. Of these, 58 patients and 56 controls were selected for measurement of plasma ATG5 level using ELISA. The relevance of disease-associated SNPs was evaluated using the SHEsis program. We identified a significant association between rs6568431 and CP (OR = 1.388, 95% CI = 1.173~1.643, Pallele = 0.0005, Pgenotype = 0.0015). Subgroup analysis showed a highly significant association of rs6568431 with spastic CP (n = 468, OR = 1.511, 95% CI = 1.251~1.824, Pallele = 8.50e-005, Pgenotype = 1.57e-004) and spastic quadriplegia (OR = 1.927, 95% CI = 1.533~2.421, Pallele = 7.35e-008, Pgenotype = 3.24e-009). Furthermore, mean plasma ATG5 levels were lower in CP patients than in controls, and individuals carrying the AA genotype of rs6568431 that was positively associated with CP had lower plasma ATG5 levels (P < 0.05). This study demonstrated an association of an ATG5 gene variant and low level of ATG5 protein with CP, and stronger associations with severe clinical manifestations were identified. Our results provide novel evidence for a role of ATG5 in CP and shed light on the molecular mechanisms underlying this neurodevelopmental disorder.