Angiotensin-converting enzyme and angiotensin II type 1 receptor gene polymorphisms in children with subacute sclerosing panencephalitis

Novel Genetic Variants Distinguishing Myelin Oligodendrocyte Glycoprotein-IgG-Positive From Myelin Oligodendrocyte Glycoprotein-IgG-Negative Pediatric Acute Disseminated Encephalomyelitis in Northern China

BACKGROUND

Acute disseminated encephalomyelitis (ADEM) is a common phenotype in children with myelin oligodendrocyte glycoprotein IgG (MOG-IgG)-associated disease. We aimed to identify novel genetic variants that distinguish children with MOG-IgG-positive ADEM (MOG-IgG+ ADEM) from children with MOG-IgG-negative ADEM (MOG-IgG- ADEM) using whole exome sequencing (WES) analysis.

METHODS

We conducted a two-stage study design. First, we performed WES on five patients with MOG-IgG+ ADEM and five patients with MOG-IgG- ADEM. Following bioinformatics analysis, the candidate variant list was constructed. Second, 29 children with MOG-IgG+ ADEM and 27 children with MOG-IgG- ADEM, together with discovery cohort, were genotyped to identify the novel variants.

RESULTS

WES resulted in 33,999 variants, and 5388 nonsynonymous variants were selected for downstream analysis. In total, 118 protein-affecting variants that were significantly different between the two groups were identified. Together with the five variants extracted from the literature, 49 variants were selected as the candidate variant list for genotyping in the replication cohort. Finally, we identified three variants: rs11171951 in NACα, rs231775 in CTLA4, and rs11171951 in GOLGA5, which were significantly different between MOG-IgG+ ADEM and MOG-IgG- ADEM. Only rs12440118 in NACα remained significant after Bonferroni correction for multiple testing (Padj < 0.001).

CONCLUSIONS

We identified strong associations between NACα, CTLA4, and GOLGA5 variants and MOG-IgG+ ADEM in a Han Chinese population of Northern China, which may present novel genetic risk factor distinguishing patients with MOG-IgG+ ADEM from those with MOG-IgG- ADEM.

Angiotensin-converting enzyme gene insertion/deletion polymorphism with metabolic syndrome in Turkish patients

BACKGROUND

The ACE gene has received substantial attention in recent years as candidate for a variety of diseases. The most common polymorphism in ACE gene is the Insertion/Deletion (I/D, rs4646994) polymorphism located on intron 16.

AIM

We investigated the association between metabolic syndrome (MS) and the insertion (I) - deletion (D) polymorphisms in the angiotensin converting enzyme (ACE) gene in south-east of Turkey.

SUBJECTS AND METHODS

One hundred and sixty subjects, with 101 cases of MS and 59 age- and gender-matched healthy controls were included in the study.

RESULTS

The frequency of ACE I/D polymorphism was found to be 49.5% for DD, 36.6% for ID, and 13.9% for II in the MSstudy group and 44.1% for DD, 42.4% for ID and 13.5% for II in the control group. Allele frequencies were found to be 0.68% for D and 0.32% for I allele in the study group with MS and 0.65% for D, 0.35% for I allele in the control group. The I/D polymorphism of the ACE gene, DD, ID, and II genotypes occurred with similar frequencies in the study group with MS and the control group with no significant differences (p<0.05). On applying one-way analysis of variance to different ACE gene polymorphic groups in patients with MS were not significantly associated to ACE gene polymorphism and waist circumference, systolic blood pressure, diastolic blood pressure, fasting blood glucose, HDL, and LDL (p<0.05).

CONCLUSIONS

Further studies of patients in larger numbers and of different ethnic backgrounds may be necessary to elucidate the association between the ACE I/D gene polymorphism and MS.

Characteristics of viruses derived from nude mice with persistent measles virus infection

Measles virus (MV) isolates from patients with subacute sclerosing panencephalitis (SSPE) differ from wild-type MV virologically. However, few animal models have reported viruses with characteristics of the SSPE virus. The MV Edmonston strain was inoculated into the subarachnoid space of nude mice. All nude mice displayed weight loss and required euthanasia, with a mean survival duration of 73.2 days. The viral load in the brain was 4- to 400-fold higher than the inoculated load, and brain infection was confirmed by immunostaining. Gene sequencing of the viruses revealed that amino acid mutations occurred more frequently in matrix proteins. The most common mutation was a uridine-to-cytosine transition. The virus exhibited lower free virus particle formation ability than the Edmonston strain. When nude mice were challenged with 2 × 10(2) PFU of the brain-derived virus, the mean survival duration was 34.7 days, which was significantly shorter than that of the mice challenged with 4 × 10(4) PFU of the Edmonston strain (P < 0.01). This study indicated that MV in a nude mouse model of persistent infection exhibited characteristics of the SSPE virus. This model may prove useful in elucidating the pathogenic mechanism of SSPE and developing potential therapeutics.

Survey of subacute sclerosing panencephalitis in Japan

Investigators conducted a retrospective epidemiological study of subacute sclerosing panencephalitis, a fatal disease caused by measles infection, over the past few years in Japan. Data on 118 cases obtained from a questionnaire sent to attending physicians were analyzed. The annual incidence of subacute sclerosing panencephalitis was approximately 0.03 cases per million from 2001 to 2005. Children infected with measles at a young age (<12 months) showed a high incidence of subacute sclerosing panencephalitis, and those infected before 6 months of age showed earlier onset. Because a positive correlation was found between the prevalence of measles and the onset of subacute sclerosing panencephalitis, particularly among children infected at an early age, it is vital to eradicate measles infection by vaccination.

Are SCN1A gene mutations responsible for genetic susceptibility to subacute sclerosing panencephalitis?

Dravet syndrome, characterized predominantly by myoclonus, has a striking clinical resemblance to subacute sclerosing panencephalitis (SSPE). Patients with Dravet syndrome develop significant mental decline with advancing age of affected child like in SSPE. It is well established that SCN1A gene mutations are associated with Dravet syndrome. Even periodic EEG complexes have been described in Dravet syndrome. In addition to Dravet syndrome, several other types of acute and subacute encephalopathic syndromes having clinical and electroencephalographic resemblance to SSPE are associated with SCN1A gene mutations. SSPE is a devastating progressive inflammatory disorder of the central nervous system. It is caused by persistent infection of the brain by an aberrant measles virus. Only a few of a vast number of measles infected pediatric population develop SSPE. There are several reports describing presence of SSPE is close relatives and it has been described previously in sibling and twin pairs. A genetic susceptibility for development of SSPE is likely. In fact, a variety of genetic abnormalities have already been described in patients with SSPE. It can also be argued that because of striking clinical resemblance between Dravet and various epileptic and encephalopathic syndromes associated with SCN1A gene mutations and SSPE, SCN1A gene abnormalities may also be responsible for susceptibility to SSPE in measles infected children.