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Objective:To analyze the characteristic of prenatal serological screening in fetus with X-linked ichthyosis (XLI), and to explore the relationship between unconjugated estriol (uE 3) levels and XLI. Methods:A total of 56 fetuses with Xp22.31 microdeletion indicated by prenatal diagnosis and 70 fetuses diagnosed with trisomy 21 and 26 fetuses with trisomy 18 in Henan Provincial People's Hospital and Affiliated Hospital of Weifang Medical College from September 2016 to June 2021 were collected. The multiples of median (MoM) values of uE 3, alpha-fetoprotein (AFP), and human chorionic gonadotropin (hCG) during the second trimester of pregnancy were retrospectively analyzed. Prenatal diagnosis was made by amniotic fluid karyotype analysis and genome copy number variant analysis, parent genetic verification and pathogenicity analysis were performed, and maternal and infant outcomes were followed up. Results:Of 56 pregnant women with fetal Xp22.31 microdeletion, 43 underwent serological screening during the second trimester of pregnancy, of which 42 were abnormal (39 male fetuses and 3 female fetuses). The median uE 3 MoM value of 39 male fetuses [0.06 (0.00-0.21)] was lower than the normal value and significantly lower than that of fetuses with trisomy 21 [0.71 (0.26-1.27)] and fetuses with trisomy 18 [0.36 (0.15-0.84)], the difference was statistically significant ( Z=99.96, P<0.001). While the MoM values of AFP and hCG were all within the normal range. Among the 56 fetuses carrying Xp22.31 microdeletion, 45 were male fetuses and 11 were female fetuses, and the deletion fragments all involved STS gene. Eighty-nine percent (50/56) were inherited from mother (49 cases) or father (1 case), and 11% (6/56) were de novo mutations. Follow-up showed 48 live births (38 males and 10 females) and 8 chose to terminate pregnancy (7 males and 1 female). Among the 38 male newborns, 37 presented with scaly skin changes from 1 to 3 months of age, and one had no clinical manifestations until 4 months after birth. Ten female newborns had no obvious clinical manifestations. Conclusions:The decrease levels of uE 3 MoM on maternal serological screening is closely related to the higher risk of XLI in male fetuses. For pregnant women with low uE 3 in serological screening or with family history of ichthyosis, in addition to chromosomal karyotype analysis, joint detection of genomic copy number variant analysis should be recommended.
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Objective@#To evaluate the application value and significance of low-depth whole-genome sequencing for copy number variations (CNV-Seq) in the genetic diagnosis and prenatal diagnosis of X-linked ichthyosis (XLI) due to STS gene deletion.@*Methods@#Clinical data were collected from 3 616 subjects who received CNV-Seq, and single-gene test results were collected from 7 patients or pedigrees with ichthyosis in The First Affiliated Hospital of Zhengzhou University in 2018. The 3 616 samples included 2 891 prenatal samples from pregnant women (most were amniotic fluid samples, some fetal villus samples, very few umbilical blood samples) and 725 peripheral blood samples from other subjects. Genomic DNA was extracted from amniocytes or peripheral blood, and then subjected to CNV-Seq. Quantitative PCR (qPCR) and single nucleotide polymorphism (SNP) -comparative genomic hybridization (CGH) array were performed to verify the detected CNVs. Pathogenicity of the CNVs was analyzed according to the database of genomic variants (DGV) , database of genomic variation and phenotype in humans using ensembl resources (DECIPHER) , clinical genome resource (ClinGen) and online Mendelian inheritance in man (OMIM) .@*Results@#Of the 3 616 subjects receiving CNV-Seq, Xp22.31 deletion was identified in prenatal samples from 6 pregnant women, including 5 male and 1 female fetuses. The deleted fragment of Xp22.31 covered the XLI region containing the major gene STS. The parental CNV-Seq showed that the Xp22.31 deletion was spontaneous mutation in 2 of the 6 fetuses, and inherited from the parents in the other 4 fetuses. qPCR confirmed that the female fetus was a carrier of a complete heterozygous deletion of the STS gene, and there was a complete deletion of the STS gene in the other 5 male fetuses. SNP-CGH array also confirmed that the female fetus was heterozygous Xp22.31 deletion carrier, which was consistent with the CNV-Seq results. Ichthyosis gene panel sequencing in the 7 patients with ichthyosis showed 1 with harlequin ichthyosis, 2 with ichthyosis vulgaris, 3 with XLI, and no causative mutation in 1. CNV-Seq confirmed that Xp22.31 deletion existed in the above 2 patients with XLI due to STS gene deletion. Moreover, Xp22.31 duplication was found in 16 out of 3 616 subjects receiving CNV-Seq, but they were all individuals or fetuses with normal phenotype.@*Conclusions@#CNV-Seq is a stable and reliable method for screening whole-genome CNVs, and can be applied to genetic diagnosis and prenatal diagnosis of XLI due to STS gene deletion. The deletion of Xp22.31 fragment containing the STS gene can cause XLI, and the duplication of the same region is highly likely to be the polymorphic variation.
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Objective To analyze genetic testing and prenatal diagnosis of two pedigrees with X-linked ichthyosis.Methods Karyotyping,bacterial artificial chromosomes-on-BeadsTM (BoBs),fluorescence in situ hybridization (FISH) and single nucleotide polymorphism array (SNP-array) were used to detect amniotic fluid and peripheral blood specimens of two pedigrees,one with and one without known family history of ichthyosis.Clinical data was collected and analyzed as well.Results (1) The pedigree without known family history:Prenatal BoBs showed that the XC1 probe of fetus Ⅳ-12 was from 0.36 to 0.50,suggesting the presence of microdeletion.SNP-array analysis of gravida Ⅲ-13 showed a 1.68 Mb copy number deletion at Xp22.31 and four missing Online Mendelian Inheritance in Man (OMIM) genes (HDHD1,STS,VCX and PNPLA4).Fetal SNP-array revealed a deletion of arr[hg19] Xp22.31 (6 455 151-8 135 644)× 0,indicating a maternally inherited one.FISH analysis verified the deletion in STS gene in fetus Ⅳ-12,whose karyotype was 46,XY.The gravida's female cousin (Ⅲ-21) and nephew (Ⅳ-14) also had STS gene deletion,which size was the same as that from the gravida and the fetus.Fetus (Ⅳ-12) was delivered at term by cesarean section with normal skin,but an extensive white scales appeared on the abdomen one week after birth and the symptom was aggravated when the weather was dry.The infant was followed up to eight months old and no other clinical symptoms were found.(2) The pedigree with known family history:SNP-array revealed that a 1.2 Mb copy number deletion at Xp22.31 and four missing OMIM genes (HDHD1,STS,VCX and PNPLA4) were detected in pregnant women (Ⅲ-21),proband (Ⅳ-16) and fetus (Ⅳ-17).FISH analysis of the fetus verified the deletion in STS gene.The karyotype of the fetus was 46,XY.Fetus Ⅳ-17 was delivered at term by cesarean section with normal skin,but white scales widely appeared on the abdomen ten days after birth.The infant was followed up to four months old and no other clinical symptoms were found.Conclusion Molecular genetic techniques such as BoBs,FISH and SNP array are used in combination in this study to provide genetic testing and prenatal diagnosis to two XLI pedigrees,which is helpful for clinical diagnosis and genetic counseling.
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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.