Genetic analysis of albinism caused by compound heterozygous mutations of the OCA2 gene in a Chinese family.

BACKGROUND: Oculocutaneous albinism (OCA) is a group of rare genetic disorders characterized by a reduced or complete lack of melanin in the skin, hair, and eyes. Patients present with colorless retina, pale pink iris, and pupil, and fear of light. The skin, eyebrows, hair, and other body hair are white or yellowish-white. These conditions are caused by mutations in specific genes necessary for the production of melanin. OCA is divided into eight clinical types (OCA1-8), each with different clinical phenotypes and potential genetic factors. This study aimed to identify the genetic causes of non-syndromic OCA in a Chinese Han family. METHODS: We performed a comprehensive clinical examination of family members, screened for mutation loci using whole exome sequencing (WES) technology, and predicted mutations using In silico tools. RESULTS: The patient's clinical manifestations were white skin, yellow hair, a few freckles on the cheeks and bridge of the nose, decreased vision, blue iris, poorly defined optic disk borders, pigmentation of the fundus being insufficient, and significant vascular exposure. The WES test results indicate that the patient has compound heterozygous mutations in the OCA2 gene (c.1258G > A (p.G420R), c.1441G > A (p.A481T), and c.2267-2 A > C), respectively, originating from her parents. Among them, c.1258G > A (p.G420R) is a de novo mutation with pathogenic. Our analysis suggests that compound heterozygous mutations in the OCA2 gene are the primary cause of the disease in this patient. CONCLUSIONS: The widespread application of next-generation sequencing technologies such as WES in clinical practice can effectively replace conventional detection methods and assist in the diagnosis of clinical diseases more quickly and accurately. The newly discovered c.1258G > A (p.G420R) mutation can update and expand the gene mutation spectrum of OCA2-type albinism.

Effect of clinical whole exome sequencing in aetiological investigation and reproductive risk prediction for a couple with monogenic inherited diseases.

Objective: To determine the genetic causes of monogenic inherited diseases in a couple using clinical whole exome sequencing (WES) and advise on their reproductive choices. Methods: WES was applied to a couple seeking reproductive advice, the female with short stature and the male with congenital cataracts. Results: (1) The woman exhibited a 13.8 Kb heterozygous deletion at chrX: 591590-605428 (hg19). This region corresponds to exons 2-6 of the short-stature homeobox-containing (SHOX) gene (NM000451). Associated diseases involving the SHOX gene range from severe Leri-Weill dyschondrosteosis to mild nonspecific short stature. Meanwhile, further validation using a quantitative reverse transcription polymerase chain reaction assay confirmed the heterozygous deletion of the SHOX gene in the proband, as well as other family members with similar clinical characteristics (the proband's mother, aunt, and cousin). Multiple pathogenic reports of this variant have been included in the HGMD database. Per the American College of Medical Genetics and Genomics (ACMG) classification criteria, this deletion is classified as pathogenic. (2) For the male patient, a heterozygous variant was detected in the CRYBB3 gene: NM004076: c.226G>A (p.Gly76R). Variants in the CRYBB3 gene can cause Cataract 22 (OMIM: 609741). At present, this variant locus is not included in databases such as the gnomAD, while both SIFT and PolyPhen2 deem this locus 'damaging'. Moreover, further validation by Sanger sequencing confirmed that the variant was inherited from the male patient's mother, who also had cataracts. According to ACMG standards and guidelines, the c.226G>A (p.Gly76Arg) variant in the CRYBB3 gene is classified as having 'uncertain significance'. Conclusion: WES identified pathogenic variants in both individuals, suggesting a 25% chance of a healthy child naturally. Third-generation assisted reproductive techniques are recommended to minimize the risk of affected offspring.

Application of Copy Number Variation Sequencing Technology in 422 Foetuses with Abnormal Ultrasound Soft Markers.

Purpose: The application value of ultrasound soft indicators in prenatal diagnosis was evaluated by copy number variation sequencing (CNV-seq). Methods: The authors conducted a retrospective analysis of 422 pregnant women who underwent CNV-seq testing at Luoyang Maternal and Child Health Hospital between January 2020 and November 2021. The women had presented with abnormal ultrasound soft markers; those identified as high-risk through non-invasive prenatal screening were excluded. Results: A total of 43 abnormal cases were detected in 422 pregnant women, including 24 aneuploidy (including chimerism) and 19 pathogenic or likely pathogenic copy number variations (CNVs). Based on the characteristics of ultrasound soft indicators, pregnant women were divided into five groups: isolated nuchal translucency (NT) group, combined NT group, isolated soft indicators group, combined soft indicators group and combined non-NT group. The abnormality detection rates in the five groups were 12.38% (13/105), 36.11% (13/36), 3.74% (4/103), 3.08% (2/63) and 10.09% (11/109), respectively. Statistical tests showed that the detection rate in the NT thickening combined with other abnormalities group was significantly higher than the other four groups, while there was no statistical difference in the detection rate among the other four groups. Conclusion: When NT thickening is combined with other abnormalities, it is more likely to indicate chromosome abnormalities or CNVs, so it should be regarded seriously upon finding, and pregnant women should be referred for prenatal diagnosis according to the examination results. In addition, NT thickening is an important indicator for prenatal diagnosis and should be considered regardless of whether it occurs independently. The authors recommend CNV-seq for prenatal diagnosis to prevent missing small fragments of CNVs during traditional karyotyping.

[Study on anti-proliferation activity and the mechanisms of alkaloid monomers from Gelsemium elegans on HepG2 cell in vitro].

OBJECTIVE: To investigate the effects of alkaloid monomers from Gelsemium elegans on proliferation of HepG2 cell in vitro and the possible mechanism. METHODS: MTT assay was used to measure the inhibitory of three alkaloid monomers on HepG2 cell in vitro. The most effective fraction was chosen to test whether the effect was in time-and dose-dependent manner. The morphological changes were observed by the light microscope and the cell cycle alteration through the flow cytometric assay. The activity of Caspase-3, Caspase-8 and Caspase-9 were detected by a Caspases colorimetric assay kit. RESULTS: The results showed that koumine, Gelsemine and Gelsenicine could significantly inhibit the proliferation of HepG2 cell and Gelsenicine, the most effective fraction, was clearly in dose- and time-dependent manners, while exhibited low cytotoxicity to the Vero cell. The cell treated with Gelsenicine for 48 h showed distinctive morphological changes. The cells treated with 200 and 400 microg/mL shrinked and fell off from the bottom. At the same time, the cells were arrested at S phase and the apoptosis increased apparently. The activity of Caspase-3, Caspase-8 and Caspase-9 was increased in a dose-dependent manner. CONCLUSION: Three alkaloid monomers from Gelsemium elegans, especially Gelsenicine, could inhibit proliferation of HepG2 cell obviously. The mechanism may be related to cell cycle arrest and activation of Caspase-3, Caspase 8 and Caspase-9.