[Construction and identification of the chromosome specific DNA library.].

The objective of the present study was to construct a human chromosome 21 specific DNA library for further use in research of genetic disease. Human chromosome 21 microdissected from the peripheral blood cells were subjected to repeatedly incubation in gradient temperature bath to release DNA. The library of chromosome 21 was constructed using the DNA fragment of 100-500 bp and 500-2 000 bp recovered from the products of DOP-PCR. Florescence in situ hy-bridization (FISH) and dot blotting analyses were carried out to assess the chromosome 21 specificity of the DNA library. The results indicated that DNA of chromosome 21 was released easily after repeatedly incubation in gradient temperature bath. Recovery of DNA fragments from DOP-PCR in different size ranges improved the efficiency of cloning of large fragments. Both FISH and dot blotting analyses revealed that the DNA library constructed in this study was chromosome 21-specific. This DNA library facilitates identification and investigation of the chromosome 21 related abnormality.

[Hemoglobin H disease with a rare α-thalassemia gene mutation (--SEA/α*92A>Gα): pedigree analysis and genetic diagnosis].

OBJECTIVE: To identify a rare α-thalassemia gene mutation in a family from south China and perform a pedigree analysis and genetic diagnosis of hemoglobin H (HbH) disease caused by this mutation. METHODS: Peripheral blood samples were collected from the family members for analysis of the hematological phenotype and routine test of thalassemia genes. DNA sequencing was carried out for samples that showed genotype and phenotype inconsistency. RESULTS: A rare α-thalassemia *92A>G gene mutation was detected within this family. The proband and his sister were confirmed to have non-deletional HbH disease with α--SEA/α*92A>Gα genotype. The proband's brother was confirmed to have an α-thalassemia trait with the genotype of -α3.7/α*92A>Gα. The proband's father was identified as an α-thalassemia silent carrier with the genotype of αα/α*92A>Gα. CONCLUSION: A rare α-thalassemia *92A>G gene mutation was identified for first time in south China. The description of the basic phenotypic characteristics of α-thalassemia trait and silent carrier caused by this mutation enriches the α-thalassemia gene mutation spectrum in Chinese population and helps in population screening, clinical molecular diagnosis and genetic counseling.