ABSTRACT
Objective To detect mutations of the ABCA12 gene in 2 Chinese families with autosomal recessive congenital ichthyosis (ARCI).Methods According to the typical clinical manifestations,two probands were diagnosed with ARCI.DNA was extracted from the peripheral blood samples collected from the patients and their parents.High-throughput sequencing was conducted by using multi-gene array for genetic skin disorders to determine mutation sites in the probands,and then DNA isolated from the probands and their parents were bidirectionally verified by Sanger sequencing.Results Two compound heterozygous mutations (c.2759A＞G and c.7004A＞G) in the ABCA12 gene were found in the proband 1,and another two compound heterozygous mutations (c.6163_6164insT and c.7406G＞A) were identified in the proband 2.The parents of the two probands were heterozygous carriers of one of the two mutations in the ABCA12 gene.Function prediction for the 4 mutations showed that all of the 3 missense mutations (c.2759A＞G,c.7004A＞G and c.7406G＞A) may exert pathogenic effect,and fragnin encoded by the frameshift mutation c.6163_6164insT may also affect protein function,c.2759A＞G and c.6163_6164insT were newly identified mutation sites.Conclusion The compound heterozygous mutations in the ABCA 12 gene are the causative mutations responsible for ARCI in the two probands of the two pedigrees.
ABSTRACT
Objective To report a case of X-linked ichthyosis complicated by Mal de Meleda,and to identify the gene mutations.Methods Clinical data were collected from the patient,and peripheral blood samples were obtained from the patient,his parents and 100 unrelated healthy people who served as controls.Genomic DNA was extracted from these blood samples,and PCR was performed to amplify all the exons and their flanking sequences of the SLURP-1 and STS genes.All the amplification products were analyzed by agarose gel electrophoresis,and amplification products of the SLURP-1 gene were analyzed by DNA sequencing.Results The patient presented with regularly-arranged polygonal brown or black scales all over the trunk and limbs,erythematous hyperkeratotic lesions on the palms and soles,elbows and knees,inguinal and perianal regions,which extended to the dorsa of the hands and feet.Then,the patient was diagnosed with X-linked ichthyosis complicated by Mal de Meleda.Genetic testing showed complete deletion of the STS gene,and a homozygous mutation (c.286C ＞ T) at position 286 in exon 3 of the SLURP-1 gene,which led to the formation of a premature termination codon at amino acid position 96 (p.R96*).His parents were heterozygous carriers of the mutation (c.286C ＞ T).No mutation was found in the unrelated healthy controls.Conclusion The complete deletion of the STS gene and the homozygous nonsense mutation in the SLURP-1 gene may be the reason for X-linked ichthyosis complicated by Mal de Meleda in the patient.