OBJECTIVE: To explore the genetic basis of two fetuses with an osteogenesis imperfecta (OI) phenotype. METHODS: Two fetuses diagnosed at the Affiliated Hospital of Weifang Medical College respectively on June 11, 2021 and October 16, 2021 were selected as the study subjects. Clinical data of the fetuses were collected. Amniotic fluid samples of the fetuses and peripheral blood samples of their pedigree members were collected for the extraction of genomic DNA. Whole exome sequencing (WES) and Sanger sequencing were carried out to identify the candidate variants. Minigene splicing reporter analysis was used to validate the variant which may affect the pre-mRNA splicing. RESULTS: For fetus 1, ultrasonography at 17+6 weeks of gestation had revealed shortening of bilateral humerus and femurs by more than two weeks, in addition with multiple fractures and angular deformities of long bones. WES revealed that fetus 1 had harbored a heterozygous c.3949_3950insGGCATGT (p.N1317Rfs*114) variant in exon 49 of the COL1A1 gene (NM_000088.4). Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), it was classified as a pathogenic variant (PVS1+PS2+PM2_Supporting) for disrupting the downstream open reading frame resulting in premature translational termination, being de novo in origin, and lacking records in the population and disease databases.For fetus 2, ultrasonography at 23 weeks of gestation also revealed shortening of bilateral humerus and femurs by one and four weeks, respectively, in addition with bending of bilateral femurs, tibias and fibulas. Fetus 2 had harbored a heterozygous c.1557+3A>G variant in intron 26 of the COL1A2 gene (NM_000089.4). Minigene experiment showed that it has induced skipping of exon 26 from the COL1A2 mRNA transcript, resulting in an in-frame deletion (c.1504_1557del) of the COL1A2 mRNA transcript. The variant was inherited from its father and had been previously reported in a family with OI type 4. It was therefore classified as a pathogenic variant (PS3+PM1+PM2_Supporting+PP3+PP5). CONCLUSION The c.3949_3950insGGCATGT (p.N1317Rfs*114) variant in the COL1A1 gene and c.1557+3A>G variant in the COL1A2 gene probably underlay the disease in the two fetuses. Above findings not only have enriched the mutational spectrum of OI, but also shed light on the correlation between its genotype and phenotype and provided a basis for genetic counseling and prenatal diagnosis for the affected pedigrees.
Pregnancy ; Female ; Humans ; Osteogenesis Imperfecta/genetics* ; Collagen Type I, alpha 1 Chain ; Collagen Type I/genetics* ; Mutation ; Fetus

OBJECTIVE: To identify the pathogenic variant for a husband with osteogenesis imperfecta and provide preimplantation genetic testing (PGT) for the couple. METHODS: High-throughput sequencing and Sanger sequencing were carried out to identify the pathologic variant in the husband patients. PGT of embryos was performed through direct detection of the mutation site. Meanwhile, chromosome aneuploidy of the blastocysts was screened. Following transplantation, cytogenetic and genetic testing of fetal amniotic fluid sample was carried out during mid-pregnancy. Chromosome copy number variant (CNV) was detected at multiple sites of the placenta after delivery. RESULTS: The husband was found to harbor heterozygous c.544-2A>G variant of the COL1A1 gene. The same variant was not detected in either of his parents. PGT revealed that out of three embryos of the couple, one was wild-type for the c.544-2A site but mosaicism for duplication of 16p13.3.11.2. The other two embryos were both heterozygous for the c.544-2A>G variant. Following adequate genetic counseling, the wild-type embryo was transplanted. Amniotic fluid testing confirmed that the fetus had normal chromosomes and did not carry the c.544-2A>G variant. The copy number of chromosomes at different parts of placenta was normal after birth. CONCLUSION For couples affected with monogenic disorders, e.g., osteogenesis imperfecta, direct detection of the mutation site may be used for PGT after identifying the pathogenic variant. After adequate genetic counseling, prenatal diagnosis must be carried out to ensure the result.
Aneuploidy ; China ; Female ; Genetic Testing ; Humans ; Osteogenesis Imperfecta/genetics* ; Pregnancy ; Preimplantation Diagnosis

OBJECTIVE: To explore the genetic basis for a Chinese pedigree with two individuals suffering from congenital blindness. METHODS: Clinical data and peripheral blood samples of the pedigree were collected. Whole exome sequencing was carried out. Suspected variants were verified by Sanger sequencing. Pathogenicity of candidate variants was validated through searching of PubMed and related databases, and analyzed with bioinformatics software. RESULTS: Both patients had congenital blindness and a history of multiple fractures. Other features have included microphthalmia and cornea opacity. One patient had normal intelligence, whilst the other had a language deficit. Both patients were found to harbor compound heterozygous variants of the LRP5 gene, namely c.1007_1015delGTAAGGCAG (p.C336X), c.4400G>A (p.R1467Q) and c.4600C>T (p.R1534X). The first one was derived from their mother, whilst the latter two were derived from their father. None of the three variants was detected in their elder sister. CONCLUSION The compound heterozygous variants of c.1007_1015delGTAAGGCAG (p.C336X) and c.4600C>T (p.R1534X) of the LRP5 gene probably underlay the pathogenesis of the Osteoporosis-pseudoglioma syndrome in this pedigree. The clinical significance of the c.4400G>A (p.R1467Q) variant has remained uncertain. Above finding has enriched the mutational spectrum of Osteoporosis-pseudoglioma syndrome.
Aged ; China ; Humans ; Language ; Low Density Lipoprotein Receptor-Related Protein-5/genetics* ; Mutation ; Osteogenesis Imperfecta/genetics* ; Pedigree

OBJECTIVE: To carry out preimplantation genetic testing (PGT) for a couple where the husband was affected by osteogenesis imperfecta combined with balanced translocation using the karyomapping technique. METHODS: Blastocysts were detected using karyomapping, the carrier status of COL1A1 c.760G>A (p.Gly254Arg) variant and the carrier status of the translocated chromosome were analyzed simultaneously. RESULTS: For a total of 10 blastocysts, two euploid blastocysts were found to not carry the COL1A1 c.760G>A (p.Gly254Arg) variant but a balanced translocation. After transplanting one of the blastocysts, clinical pregnancy was achieved. Amniocentesis at 18th gestational week and prenatal genetic testing was in keeping with the result of PGT.A healthy female was born at 40+4 weeks gestation. CONCLUSION For patients simultaneously carrying genetic variant and balanced chromosomal translocation, PGT can be performed with efficiency by the use of karyomapping method.
Blastocyst ; Female ; Fertilization in Vitro ; Genetic Testing ; Humans ; Osteogenesis Imperfecta/genetics* ; Pregnancy ; Preimplantation Diagnosis ; Spouses ; Translocation, Genetic

OBJECTIVE: To explore the genetic basis for a couple with normal phenotype but repeated pregnancies with fetuses affected by osteogenesis imperfecta. METHODS: Whole exome sequencing (WES) was carried out on fetal specimens and parental DNA to detect potential pathologic variants. Suspected variants were verified by Sanger sequencing. Semen sample of the husband was collected for the extraction of genome DNA, and whole genome amplification (WGA) was performed for single sperms isolated from the sample. RESULTS: WES has identified a heterozygous c.1378G>A (p.G460S) variant of the COL1A2 gene in the fetus, which was predicted to be pathogenic but not detected in peripheral blood samples of both husband and wife. The heterozygotic variant was detected in semen DNA from the husband. Among 15 spermatozoa, 4 were found to harbor the variant. CONCLUSION The fetus was diagnosed with osteogenesis imperfecta, and the gonadal mosaicism probably accounted for the repeated abnormal pregnancies. Possibility of gonadal mosaicism should be considered when counseling couples with normal phenotype and genotype but recurrent abnormal pregnancies and/or births of children with similar phenotypes and genetic variants.
Adult ; Child ; Collagen Type I ; genetics ; Female ; Fetus ; Gonadal Disorders ; genetics ; Humans ; Male ; Mosaicism ; Mutation ; Osteogenesis Imperfecta ; diagnosis ; genetics ; Pregnancy ; Prenatal Diagnosis ; Whole Exome Sequencing

OBJECTIVE: To analyze the clinical phenotype of six pedigrees affected with osteogenesis imperfecta and their genetic basis. METHODS: Peripheral blood or abortic tissues of the six pedigrees were collected for the extraction of genomic DNA. Next generation sequencing (NGS) was carried out to detect pathological variants in the genome. Sanger sequencing was used for validating suspected variant among the six pedigrees and 100 healthy controls. RESULTS: In pedigree 1, the proband and his daughter both carried a heterozygous c.1976G>C variant of COL1A1. The probands in pedigrees 2 to 6 respectively carried heterozygous variants of c.2224G>A of COL1A2, c.2533G>A of COL1A1, c.2845G>A of COL1A2, c.2532_2540del of COL1A1, and c.1847G>A of COL1A2. The same variants were not detected in their parents and the 100 healthy controls. CONCLUSION Variants of COL1A1/2 gene probably underlie the pathogenesis for osteogenesis imperfecta in these pedigrees. Discovery of the nevol variants has enriched the spectrum of COL1A1/2 gene variants and facilitated genetic counseling and prenatal diagnosis for the affected pedigrees.
Collagen Type I ; genetics ; Female ; Genetic Variation ; Genotype ; Humans ; Male ; Mutation ; Osteogenesis Imperfecta ; genetics ; Pedigree ; Phenotype ; Pregnancy

BACKGROUND: Osteogenesis imperfecta (OI), a heritable bone fragility disorder, is mainly caused by mutations in COL1A1 gene encoding α1 chain of type I collagen. This study aimed to investigate the COL1A1 mutation spectrum and quantitatively assess the genotype-phenotype relationship in a large cohort of Chinese patients with OI. METHODS: A total of 161 patients who were diagnosed as OI in Department of Endocrinology of Peking Union Medical College Hospital from January 2010 to December 2017 were included in the study. The COL1A1 mutation spectrum was identified by next generation sequencing and confirmed by Sanger sequencing. A new clinical scoring system was developed to quantitatively assess the clinical severity of OI and the genotype-phenotype relationship was analyzed. The independent sample t-test, analysis of variance, Mann-Whitney U-test, Chi-squared test, Pearson correlation, and multiple linear regression were applied for statistical analyses. RESULTS: Among 161 patients with OI, 32.9% missense mutations, 16.8% non-sense mutations, 24.2% splice-site mutations, 24.8% frameshift mutations, and 1.2% whole-gene deletions were identified, of which 38 variations were novel. These mutations led to 53 patients carrying qualitative defects and 67 patients carrying quantitative defects in type I collagen. Compared to patients with quantitative mutations, patients with qualitative mutations had lower alkaline phosphatase level (296 [132, 346] U/L vs. 218 [136, 284] U/L, P = 0.009) and higher clinical score (12.2 ± 5.3 vs. 7.4 ± 2.4, P < 0.001), denoting more severe phenotypes including shorter stature, lower bone mineral density, higher fracture frequency, more bone deformity, vertebral compressive fractures, limited movement, and dentinogenesis imperfecta (DI). Patients would not present with DI if the glycine substitutions happened before the 79th amino acid in triple helix of α1 chains. CONCLUSIONS This presented distinctive COL1A1 mutation spectrum in a large cohort of Chinese patients with OI. This new quantitative analysis of genotype-phenotype correlation would be helpful to predict the prognosis of OI and genetic counseling.
Adolescent ; Adult ; Child ; Child, Preschool ; Collagen Type I ; genetics ; Female ; Genetic Association Studies ; High-Throughput Nucleotide Sequencing ; Humans ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Mutation ; genetics ; Osteogenesis Imperfecta ; genetics ; pathology ; Young Adult

OBJECTIVETo explore genetic mutations and clinical features of osteogenesis imperfecta type V.

METHODSClinical record of five patients (including one familial case) with osteogenesis imperfecta type V were retrospectively analyzed. Peripheral blood samples of the patients, one family member, as well as healthy controls were collected. Mutation of IFITM5 gene was identified by PCR amplification and Sanger sequencing.

RESULTSA heterozygous mutation (c.-14C>T) in the 5-UTR of the IFITM5 gene was identified in all of the patients and one mother. The clinical findings included frequent fractures and spine and/or extremities deformities, absence of dentinogenesis imperfecta, absence of hearing impairment, and blue sclera in 1 case. Radiographic findings revealed calcification of the interosseous membrane between the radius-ulna in all cases. Hyperplastic callus formation was found in 3 cases. Four had radial-head dislocation.

CONCLUSIONA single heterozygous mutation c.-14C>T was found in the 5-UTR of the IFITM5 gene in 5 patients with osteogensis imperfecta type V. The patients showed specific radiological features including calcification of interosseous membrane, hyperplastic callus formation, and radial-head dislocation.

Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Humans ; Male ; Mutation ; Osteogenesis Imperfecta ; diagnostic imaging ; genetics ; Young Adult

OBJECTIVETo detect potential mutations of COL1A1 and COL1A2 genes in four Chinese pedigrees affected with osteogenesis imperfecta (OI) and provide prenatal diagnosis for a fetus at 18th gestational week.

METHODSAll coding regions and exon/intron boundaries of the COL1A1 and COL1A2 genes were analyzed with targeted next-generation sequencing (NGS). Suspected mutations were confirmed with Sanger sequencing in the probands, unaffected relatives and 200 unrelated healthy individuals. Prenatal diagnosis for a high-risk fetus was carried out through Sanger sequencing.

RESULTSThe probands of families 1 and 2 have respectively carried a c.760G>A (p.Gly254Arg) and a c.608G>T (p.Gly203Val) mutation of the COL1A1 gene. For family 3, the proband and his daughter have carried a novel c.299-1G>C splicing mutation of the COL1A1 gene. The same mutation was not found in the fetus of this family. For family 4, the proband has carried a novel c.1990G>C (p.Gly664Arg) mutation of the COL1A2 gene. The four mutations were not found in the unaffected relatives and 200 unrelated healthy individuals.

CONCLUSIONThe mutations of the COL1A1 and COL1A2 genes probably underlie the disease in the four families. NGS combined with Sanger sequencing can provide an effective and accurate method for their genetic and prenatal diagnosis.

Adult ; Child, Preschool ; Collagen Type I ; genetics ; DNA Mutational Analysis ; Female ; High-Throughput Nucleotide Sequencing ; Humans ; Infant, Newborn ; Male ; Mutation ; Osteogenesis Imperfecta ; genetics ; Prenatal Diagnosis

OBJECTIVETo identify potential mutation of COL1A1 gene in an ethnic Han Chinese family from Henan affected with osteogenesis imperfecta (OI).

METHODSPeripheral blood samples were collected from all 11 members of the family and 50 healthy adults for the extraction of genomic DNA. All exons and introns of the COL1A1 gene were amplified by polymerase chain reaction and subjected to direct sequencing. Mutations found in the proband were analyzed through comparison with other members of the family, 50 healthy individuals and sequence from the GenBank.

RESULTSFifteen sequence variants were discovered, which included 1 missense mutation, 1 synonymous mutation and 13 intronic mutations. All of the 4 patients from the family were detected as having carried a novel heterozygous missense mutation (c.4193T>G, p.I1398S) in exon 50 of the COL1A1 gene. The father of the proband has carried the same mutation but had a normal phenotype. The same mutation was not found in other healthy members of the family.

CONCLUSIONThe OI type of this family may have been autosomal dominant with incomplete penetrance or autosomal recessive associated with COL1A1 gene mutations.

Adolescent ; Amino Acid Sequence ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; China ; Collagen Type I ; genetics ; DNA Mutational Analysis ; Family Health ; Female ; Genetic Predisposition to Disease ; ethnology ; genetics ; Heterozygote ; Humans ; Male ; Mutation ; Osteogenesis Imperfecta ; ethnology ; genetics ; Pedigree ; Penetrance ; Sequence Homology, Amino Acid ; Young Adult