Analysis of AGG interspersion of the FMR1 gene in fragile X syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze (CGG)n repeats sequence and AGG interspersion correlated with unstable expansion of FMR1 gene in a general Chinese population.</p><p><b>METHODS</b>AmplideX FMR1 PCR Kit was used to amplify 380 X chromosomes from randomly selected 176 males and 102 females, 11 permutation carriers and 10 full mutation patients have served as controls. Results of capillary electrophoresis were analyzed with GeneMapper software Version 4.0. SPSS 11.0 software was used for statistical analysis.</p><p><b>RESULTS</b>The ratio of heterozygous females was 64.70%. The number of alleles in general males and females was 15 and 14, the classes of AGG pattern was 26 and 27, respectively. The range of alleles was between 17 to 45 CGG repeats in males and 21 to 44 CGG repeats in females, and 1 male was identified as gray zone carrier. The most frequent allele was 29 CGG repeats, which was followed by 30 and 36 repeats, while 28 CGG repeats were absent. The most common AGG pattern was 9A9A9, 99.21% of the population was detected with different forms and numbers of AGG interruption, and 6A interruption pattern was found in 10.02% samples especially in individuals with more CGG repeats. However, 57.58% of control samples had no AGG interruption, and none of the controls had 6A interruption pattern. No significant difference was observed in allele frequent distribution of (CGG)n repeats and AGG interspersion patterns between the males and females (P > 0.05), and AGGs was significantly different between general population and controls (P < 0.05).</p><p><b>CONCLUSION</b>AGGs and AGG pattern may have important roles in maintaining (CGG)n stability in general population of China, 9A9A6A9 may be a special pattern for preventing (CGG)n unstable expansion in Asian populations.</p>

Phenotypic and genetic analysis of a patient presented with Tietz/Waardenburg type II a syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the genetic cause for a patient featuring decreased pigmentation of the skin and iris, hearing loss and multiple congenital anomalies.</p><p><b>METHODS</b>Routine chromosomal banding was performed to analyze the karyotype of the patient and his parents. Single nucleotide polymorphism array (SNP array) was employed to identify cryptic chromosome aberrations, and quantitative real-time PCR was used to confirm the results.</p><p><b>RESULTS</b>Karyotype analysis has revealed no obvious anomaly for the patient and his parents. SNP array analysis of the patient has demonstrated a 3.9 Mb deletion encompassing 3p13p14.1, which caused loss of entire MITF gene. The deletion was confirmed by quantitative real-time PCR. Clinical features of the patient have included severe bilateral hearing loss, decreased pigmentation of the skin and iris and multiple congenital anomalies.</p><p><b>CONCLUSION</b>The patient, carrying a 3p13p14.1 deletion, has features of Tietz syndrome/Waardenburg syndrome type IIa. This case may provide additional data for the study of genotype-phenotype correlation of this disease.</p>