Mutation analysis of the COL7A1 gene in 4 cases of recessive dystrophic epidermolysis bullosa / 中华皮肤科杂志

Objective:To analyze gene mutations in and clinical phenotypes of 4 children with recessive dystrophic epidermolysis bullosa (RDEB) .Methods:Clinical data were collected from 4 children with RDEB, and DNA was extracted from peripheral blood samples of the children and their parents. A multi-gene panel targeting congenital epidermolysis bullosa was used for high-throughput sequencing. After identification of causative gene mutations, Sanger sequencing was performed to bidirectionally verify the mutations in the patients and their parents.Results:Genetic testing showed 8 compound heterozygous mutations in the COL7A1 gene in the 4 cases. Case 1 was diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.7828C>T and a maternal mutation c.448G> A; case 2 was also diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.3625_3635del and a maternal mutation c.2726_2728del; case 3 was diagnosed with localized RDEB, carrying a paternal mutation c.682+1G>A and an allelic mutation c.5532+1G>A, but the mutation c.5532+1G>A was not identified in the DNA extracted from the parental peripheral blood samples; case 4 was diagnosed with severe generalized RDEB, and inherited a paternal mutation c.5196delC and a maternal mutation c.500_501insAGGG. Among these mutations, c.2726_2728del and c.5196delC had not been reported previously.Conclusions:All the 4 children with RDEB carried compound heterozygous mutations in the COL7A1 gene, which may be the cause of RDEB. The phenotypes of biallelic frameshift mutation carriers appearred more severe than those of carriers of compound heterozygous mutations composed of biallelic splice site, missense and nonsense, frameshift and amino acid deletion or insertion mutations.

Pycnodysostosis caused by CTSK mutation:one pedigree study / 中华内分泌代谢杂志

The purpose of this study was to analyze the clinical characteristics of a patient with pycnodysostosis caused by cathepsin K ( CTSK ) gene mutation and his family members in order to improve the understanding of this rare diseases. A pediatric patient with pycnodysostosis was referred to us when he was eight years old. He presented with elevated bone mineral density, short stature, dentition abnormality and multiple fractures of right tibia. Next generation sequencing ( NGS) and Sanger sequencing confirmed that the proband carried carrying compound heterozygous mutations of cathepsin K(CTSK) gene, including a missense mutation c.440C>T in exon 5 (p.Ala147Val) and a deletion mutation c. 778delA in exon 6 ( p. Ser260AlafsX15) which was inherited from his father. His mother and sister did not carry the above variations. Clinically, it is necessary to differentiate pycnodysostosis from osteopetrosis and other osteosclerotic diseases.

Mutation analysis of AAAS gene in a child with Allgrove syndrome / 中华内分泌代谢杂志

Objective To study the AAAS gene mutations in a child with autosomal recessive Allgrove syndrome. Methods Clinical data were collected and blood samples were obtained from the proband of Allgrove syndrome and her parents. Genomic DNA was extracted and sequenced by PCR amplification. Subclone sequencing was performed to validate the gene mutations. The disease-causing potentials of mutation genes were evaluated by the Mutation Taster, and the target protein tertiary structure was modelled by the Swiss Model. Results A new heterozygous insertion mutation(c. 1347_1348insG) of exon 15 in the proband was identified and firstly reported. Other two reported mutations were detected, which were the heterozygous mutation c. 688C>T in the patient and her mother, and the homozygous mutation c. 855C>T in the proband and her parents. In addition, it was confirmed that the novel compound heterozygous mutations(c. 688C>T, c. 1347_1348insG) in the AAAS gene of the proband were pathogenic mutation locus. Conclusion The heterozygous mutation(c. 1347_1348insG) of AAAS gene was firstly reported. In case of the patients being clinically misdiagnosed, related-gene detection should be performed for the patients who were diagnosed with primary adrenal insufficiency during the period of infants and young childhood.

Novel compound heterozygous mutations of ALDH1A3 contribute to anophthalmia in a non-consanguineous Chinese family

Abstract Anophthalmia is a rare eye development anomaly resulting in absent ocular globes or tissue in the orbit since birth. Here, we investigated a newborn with bilateral anophthalmia in a Chinese family. Exome sequencing revealed that compound heterozygous mutations c.287G > A (p.(Arg96His)) and c.709G > A (p.(Gly237Arg)) of the ALDH1A3 gene were present in the affected newborn. Both mutations were absent in all of the searched databases, including 10,000 in-house Chinese exome sequences, and these mutations were confirmed as having been transmitted from the parents. Comparative amino acid sequence analysis across distantly related species revealed that the residues at positions 96 and 234 were evolutionarily highly conserved. In silico analysis predicted these changes to be damaging, and in vitro expression analysis revealed that the mutated alleles were associated with decreased protein production and impaired tetrameric protein formation. This study firstly reported that compound heterozygous mutations of the ALDH1A3 gene can result in anophthalmia in humans, thus highlighting those heterozygous mutations in ALDH1A3 should be considered for molecular screening in anophthalmia, particularly in cases from families without consanguineous relationships.

Adult hypophosphatasia caused by ALPL mutation: one pedigree study / 中华内分泌代谢杂志

An adult patient with hypophosphatasia caused by compound heterozygous mutations in alkaline phosphatase,liver /bone /kidney(ALPL)gene was investigated through comprehensively reviewing the medical history and clinical records of the proband and her family members in order to better understand the disease.The proband and her older sister had mild decreased serum alkaline phosphatase level accompanied with frequently nontraumatic fractures at limbs and all the teeth fell off at the age of 20 and 7, respectively.Both of them carried a missense mutation c.407G>A(p.Arg136His)in exon 5 and a deletion mutation c.1318_1320delAAC(p.Asn440del)in exon 12 simultaneously.Other four family members were p.Arg136His mutation carriers and two members were p.Asn440del mutation carriers.We found that p.Asn440del mutation was associated with the oral disorders.In this family, compound heterozygous manifested more serious symptoms, while heterozygous showed relatively mild symptoms.In addition, it is necessary to differentiate it from primary osteoporosis and other diseases of disturbed bone mineralization.