[Mutation screening and prenatal diagnosis of hidrotic ectodermal dysplasia in a Chinese family]

To analyze the mutations in Cx30 gene in a Chinese family with hidrotic ectodermal dysplasia (HED) and to make prenatal diagnosis on the embryo which has been pregnant for 5 months.

A family including 2 affected and 4 unaffected individuals was collected, and their informed consents were obtained. The affected woman had a five-month pregnancy. An 884 bp fragment containing the whole GJB6 coding sequence was amplified by PCR and the products were bi-direction sequenced directly. The mutation was further confirmed with restriction endoenzyme digesting. On the base of successful gene diagnosis, the following detection procedure on the pregnant baby was performed. First the whole coding region of Cx30 was amplified using primers Cx30-F and Cx30-R and the PCR products were digested by Hae II. Then the PCR products were cloned into pUCm-T vector. Blue-white blot screening method and PCR-restriction endoenzyme digesting technique were used to identify the correct clones. The mutant allele clone was sequenced to confirmed the mutation.

A heterozygous missense mutation 263C --> T in the Cx30 gene was detected in the affected little girl and her affected mother, which led to an amino acid substitution (A88V) in the second transmembrane domain of GJB6. The mutation was confirmed by Hae II digestion. A88V mutant allele cannot be cut while the wild normal allele can be cut into two fragments, 520 and 278 bp. The result of analyse on the five-month pregnancy show the embryo carried the A88V mutation too. So the embryo will be a patient.

An A88V missense mutation in the Cx30 gene can also cause HED in Chinese Han population. Based on the gene diagnosis, prenatal diagnosis can be played using bi-direction sequencing and confirmed with restriction endoenzyme digesting.