Quantitative Relaxometry Assessment of Brain Microstructural Abnormality of Preschool Children With Autism Spectrum Disorder With Synthetic Magnetic Resonance Imaging.

OBJECTIVE: This study aimed to perform an assessment of brain microstructure in children with autism aged 2 to 5 years using relaxation times acquired by synthetic magnetic resonance imaging. MATERIALS AND METHODS: Thirty-four children with autism spectrum disorder (ASD) (ASD group) and 17 children with global developmental delay (GDD) (GDD group) were enrolled, and synthetic magnetic resonance imaging was performed to obtain T1 and T2 relaxation times. The differences in brain relaxation times between the 2 groups of children were compared, and the correlation between significantly changed T1/T2 and clinical neuropsychological scores in the ASD group was analyzed. RESULTS: Compared with the GDD group, shortened T1 relaxation times in the ASD group were distributed in the genu of corpus callosum (GCC) ( P = 0.003), splenium of corpus callosum ( P = 0.002), and right thalamus (TH) ( P = 0.014), whereas shortened T2 relaxation times in the ASD group were distributed in GCC ( P = 0.011), left parietal white matter ( P = 0.035), and bilateral TH (right, P = 0.014; left, P = 0.016). In the ASD group, the T2 of the left parietal white matter is positively correlated with gross motor (developmental quotient [DQ] 2) and personal-social behavior (DQ5), respectively ( r = 0.377, P = 0.028; r = 0.392, P = 0.022); the T2 of the GCC was positively correlated with DQ5 ( r = 0.404, P = 0.018); and the T2 of the left TH is positively correlated with DQ2 and DQ5, respectively ( r = 0.433, P = 0.009; r = 0.377, P = 0.028). All significantly changed relaxation values were not significantly correlated with Childhood Autism Rating Scale scores. CONCLUSIONS: The shortened relaxometry times in the brain of children with ASD may be associated with the increased myelin content and decreased water content in the brain of children with ASD in comparison with GDD, contributing the understanding of the pathophysiology of ASD. Therefore, the T1 and T2 relaxometry may be used as promising imaging markers for ASD diagnosis.

[Cytogenetic and molecular analysis of a case of Prader-Willi syndrome].

OBJECTIVE: To investigate the significance of cytogenetic and molecular genetic diagnosis of a special type of secondary sexual dysplasia and the applicability of various methods for its detection. METHODS: Using karyotype analysis, array comparative genomic hybridization (aCGH), multiplex ligation-dependent probe amplification (MLPA) and methylation-specific PCR (MS-PCR), we diagnosed and differentially diagnosed a case of secondary sexual dysplasia. RESULTS: Abnormalities were not found in the karyotype analysis or the SRY and AZF gene detection, nor chromosomal duplication and deletion in the initial SurePrint G3 Human CGH Array Kit8×60K.SurePrint G3 unrestricteda CGH ISCA v2,88×60K, however, identified a 68.9 kb deletion of chromosome 15 (hg19:25190737-25259677). MLPA revealed the deletion of exon 3 of the SNRPN gene. MS-PCR showed a significant decrease in the paternal fragment signals, but no difference in the maternal fragment signals between the sample from the patient and that from the control. CONCLUSIONS: The patient was confirmed with Prader-Willi syndrome by various methods of detection.

Cloning, expression and enzyme activity delineation of two novel CANT1 mutations: the disappearance of dimerization may indicate the change of protein conformation and even function.

BACKGROUND: Desbuquois dysplasia (DBQD) was a rare autosomal recessive skeletal dysplasia. Calcium activated nucleotidase 1 (CANT1) mutation was identified as a common pathogenic change for DBQD type 1 and Kim variant but not for DBQD type 2. To our knowledge, all patients with DBQD type 1 currently found could be explained by mutations in the CANT1 gene, but mutations in the CANT1 gene might not be directly diagnosed as DBQD type 1. RESULTS: We have identified two novel CANT1 mutations (mut1: c.594G > A [p.Trp198*], mut2: c.734C > T [p.Pro245Leu]) in three children from a family of Chinese origin for the first time. Two of the three children could be diagnosed as typical DBQD type 1 and one child could not be diagnosed as DBQD type 1 based on the clinical data we had. To further clarify the effect of the two mutations of the CANT1 gene, we studied the CANT1 gene expression and detected the protein secretion and nucleotide enzyme activity through cDNA cloning and expression vectors construction for wild and mutant types. The mut1 was a nonsense mutation which could lead to premature termination and produced the truncated bodies; The CANT1 dimer of mut2 was significantly reduced and even undetectable. The extracellular secretion of mut1 was extremely high while mut2 was significantly reduced compared with the wild type. And mut1 and mut2 also could result in a significant reduction in the activity of CANT1 nucleotidease. From the results we could deduce that the two mutations of the CANT1 gene were the causes of the two cases in this study. CONCLUSIONS: Regarding the particularity of the cases reported in this study, the pathogenesis of CANT1 might be more complicated. The genetic and phenotype of three children with the same genetic background need to be further studied. Larger cohort of patients was needed to establish genotype-phenotype correlations in DBQD.

Study of genetic diversity of killer cell immunoglobulin-like receptor loci in the Tujia ethnic minority.

The aim of this study was to analyze the genetic profiles of 14 killer cell immunoglobulin-like receptor (KIR) genes and 2 pseudogenes of 124 individuals from Tujia ethnic minority residing in Enshi Tujia and Miao autonomous prefecture of Hubei province of China and investigate the genetic relationships between the Tujia ethnic minority and other reported groups for the first time. Sequence specific primer amplification (PCR-SSP) methods were used to genotype the 14 KIR genes and 2 pseudogenes. The observed carrier frequencies (OF) and the gene frequencies (GF) of the KIR genes were measured. Neighbor-joining (N-J) tree and the principal component analysis (PCA) plot were constructed. All individuals were typed positive for the three framework loci KIR3DL3, 2DL4 and 3DL2, as well as for pseudogene KIR3DP1. The gene frequencies of the other KIR genes ranged from 9% in KIR2DS2 to 98% in KIR2DP1 and KIR3DL1. The present study of the KIR genes may be a powerful tool for enriching the Chinese ethnical gene information resources of the KIR gene pool, as well as for the anthropological research.