Molecular testing strategies in the evaluation of fetal skeletal dysplasia

Prenatal Diagnosis of a Lethal Skeletal Dysplasia.

Objective: To determine the accuracy and usefulness of prenatal ultrasonographic and molecular genetic diagnosis in detection of skeletal dysplasia.Methods: This study was based upon data of the 17 cases of skeletal dysplasia diagnosed by prenatal ultrasound and 7 cases by molecular diagnosis performed among the 17 cases and the 2 cases who has familial skeletal dysplasia by molecular diagnosis during the first trimester at Ewha and Eulji University from March 1998 to August 2005.A final diagnosis was sought on the basis of radiographic studies, molecular testing, or both. Results:The mean gestational age at diagnosis was 24.9 weeks (range, 17 to 35 weeks).Nine cases were diagnosed before 24 weeks.A final diagnosis was obtained in 16 cases (94.1%).There was 1 false-positive diagnosis.The antenatal diagnosis was correct in 14 cases (82.4%).The 8 cases were prenatally confirmed and 1 case was postpartum confirmed using molecular genetic testing and accurate antenatal diagnosis and prediction was done.We were able to rule out skeletal dysplasia through chorionic villus sampling during the first trimester in the 2 cases with the family history with skeletal dysplasia.Conclusion: Prenatal diagnosis of skeletal dysplasia can be a considerable diagnostic challenge.However, skeletal dysplasia is correctly diagnosed on the basis of prenatal meticulous ultrasound and antenatal prediction of lethality was highly accurate.Using prenatal molecular diagnosis, skeletal dysplasia can be diagnosed at first trimester of pregnancy and nonlethal skeletal dysplasia can be confirmed when prenatal ultrasound was nonspecific.

Skeletal dysplasias are a group of heterogeneous disorders affecting growth and morphology of the various segments of the skeleton1-4, with an estimated prevalence of 2–5/10 000 at birth5. Despite recent advances in imaging modalities and molecular genetics6, accurate prenatal diagnosis of skeletal dysplasias remains a clinical challenge7. The difficulties in prenatal diagnosis result from the large number of disorders, their phenotypic variability with overlapping features and the lack of a precise molecular diagnosis for many disorders8. Over the past 30 years, the classification of skeletal dysplasias has evolved from one based upon clinical/radiological/pathological descriptions to one that also includes the underlying molecular abnormality for a few conditions in which the defect is known9. The last version of the International Nosology and Classification of Constitutional Disorders of Bone was published in 200210 and included approximately 300 conditions, of which approximately 50 are apparent and identifiable at birth11. These conditions are relevant to the maternal–fetal medicine specialist as they constitute the group which may be detected before birth. Prenatal diagnosis is easier in the presence of a positive family history and a precise description of the phenotype since many disorders are inherited as autosomal dominant or recessive disorders6. However, it is not unusual that skeletal dysplasias are first suspected during routine sonographic examination after a shortened long bone or other abnormal skeletal finding is observed7. Sonographic evaluation requires a detailed examination of the fetal skeleton, which is described in Table 1. The sonologist must determine if the anomaly is lethal, either by establishing the precise diagnosis of uniformly lethal conditions (Table 2)6 or assessing the risk of pulmonary hypoplasia6, 12-35. Several parameters have been proposed to estimate the risk of pulmonary hypoplasia (see Table 3)6, 12-47. 2.Compare with other segments and classify the limb shortening as: Rhizomelia Mesomelia Acromelia Severe micromelia 3.Qualitative assessment of long bones: Bowing Demineralization Fractures Metaphyseal flaring Absence of bones 5.Evaluate hands and feet Digits (polydactyly/syndactyly) Positional deformities 6.Evaluate the cranium Macrocrania Frontal bossing Cloverleaf skull Hypertelorism/hypotelorism 8.Examination of the spine Platyspondyly Demineralization Hemivertebrae Coronal clefts Vertebral disorganization With the identification of a growing number of mutations responsible for skeletal dysplasias48-50, it is hoped that eventually a specific diagnosis will be possible during the prenatal period51-55. A classification of genetic disorders of the skeleton based on the structure and function of implicated genes and proteins has been proposed recently50, complementing the existing International Nosology and Classification of Constitutional Disorders of Bone10. Accurate diagnosis is important for both proper management of the index case and for genetic counseling56. Moreover, if patients resort to pregnancy termination, molecular diagnostic methods may be the only way to establish the final diagnosis5. For detailed and up-to-date information regarding molecular tests available for the diagnosis of skeletal dysplasias the reader is referred to the web pages of GeneTests (a comprehensive source of information on genetic testing funded by the National Institutes of Health of the USA: http://genetests.org), the European Skeletal Dysplasia Network (http://www.esdn.org/diagnosis.html), the Division of Molecular Pediatrics of the University of Lausanne, Switzerland (http://www.pediatrics.ch/Frames.html) or the International Skeletal Dysplasia Registry at Cedars-Sinai Hospital, Los Angeles, USA (http://www.cedars-sinai.edu/3810.html). The reader is referred to a recent novel article describing how phenotypic relationships could be exploited to find new disease genes and provide clues to gene interactions, pathways and functions57. Despite the increasing availability of molecular testing, a comprehensive molecular diagnostic search for all skeletal dysplasias is not possible at this time. Therefore, the role of imaging is to narrow the differential diagnosis so that specific biochemical and molecular tests can be performed to confirm or exclude a potential diagnosis8, 58-60. Ultrasound is the primary imaging modality used for the initial diagnostic evaluation of an affected fetus. Table 4 summarizes the diagnostic accuracy of two-dimensional ultrasound (2D-US) for prenatal diagnosis of skeletal dysplasias7, 61-64. A precise diagnosis has been reported in 31–65% of cases. The introduction of 3D-US and rendering algorithms to reconstruct the fetal skeleton can improve diagnostic accuracy because additional phenotypic features not detectable by 2D-US may be identified65-77. For example, Garjian et al.68 and Krakow et al.75 reported the diagnosis of additional facial68, 75, scapular anomalies68 and abnormal calcification patterns75 in fetuses with skeletal dysplasias, whereas Moeglin and Benoit71 used the multiplanar visualization method to demonstrate the ‘pointed appearance’ of the upper femoral diaphysis in a case of achondroplasia. Three-dimensional reconstruction of the fetal bones is best performed using the ‘maximum intensity projection’ mode, a rendering algorithm that prioritizes the display of the highest gray levels contained within a region of interest selected by the operator68, 71. If the fetus is examined early enough during pregnancy, the entire skeleton can be included within the region of interest of the three-dimensional volume dataset and, therefore, a panoramic visualization can be achieved68. However, the diagnosis may be missed, as the phenotypic characteristics of some skeletal dysplasias do not manifest until later in pregnancy. Case reports and small series of several skeletal dysplasias have been published describing phenotypic characteristics or skeletal features that were best demonstrated by 3D-US (Table 5)66, 68-71, 73-76. In this issue of the Journal, Ruano et al.78 explore for the first time the use of three-dimensional helical computerized tomography (3D-HCT) as an adjunctive imaging modality for prenatal diagnosis of skeletal dysplasias in six cases: achondroplasia (n = 3), osteogenesis imperfecta (n = 2), and chondrodysplasia punctata (n = 1). This technique consists of fast and continuous acquisition of images as the X-ray source and detector perform ‘spiral’ or ‘helical’ movements with respect to the patient, who is moving in a linear fashion through the gantry79, 80. Helical CT allows fast and continuous acquisition of a volume dataset containing the structures of interest, usually within one breathhold (20–25 s), minimizing motion artifacts79-82. Fast acquisition allows improvement in multiplanar reformatting and three-dimensional reconstruction capabilities over what is feasible with conventional CT. Similarly to 3D-US, postprocessing techniques such as ‘maximum intensity projection’, ‘surface rendering’ and ‘volume rendering’ can be used for three-dimensional reconstruction79, 81, 82. In addition, faster image acquisition with 3D-HCT when compared with conventional CT has the potential to decrease radiation exposure80-82. 3D-HCT has been previously used as an adjunctive diagnostic imaging modality for prenatal diagnosis of congenital anomalies in isolated cases of trisomy 18, cystic hygroma, congenital diaphragmatic hernia and agnathia-holoprosencephaly80, 83, 84. Long bone measurements obtained by postmortem helical CT studies have been compared with those obtained within 24 h of delivery by ultrasound, and a significant correlation between the two methods was observed85. In the study of Ruano et al.78, excellent panoramic images of the fetal skeleton were obtained by 3D-HCT without superimposition of the maternal skeleton, which occurs with radiography. Deformation of the fetal pelvis and an increase in the intervertebral space of the lumbar vertebrae were diagnosed more often using 3D-HCT when compared with 2D-US and 3D-US. In contrast, some phenotypic characteristics of fetuses with skeletal dysplasias were demonstrated only by ultrasound: phalangeal hypoplasia (by both 2D-US and 3D-US), facial dysmorphism (by 3D-US only) and point-calcified epiphysis (by both 2D-US and 3D-US). The overall count of correct phenotypic characteristics detected prenatally favored 3D-HCT over 3D-US (94.3% (33/35) vs. 77.1% (27/35), P = 0.03, McNemar's test for correlated samples). Of interest, however, was the observation that the diagnostic performance of 3D-HCT was not superior to that of 3D-US, as the correct prenatal diagnosis was established by both modalities in all cases. Provided that the two diagnostic methods have comparable diagnostic accuracy, 3D-US has two important advantages over 3D-HCT, namely, lack of radiation exposure and wider availability in the clinical setting. It is also noteworthy that the overall experience with 3D-US for the diagnosis of skeletal dysplasias is still limited65-77. Nevertheless, even in this study, 3D-US performed better than did 2D-US, both in the identification of phenotypic characteristics (77.1% (27/35) vs. 51.4% (18/35), P = 0.004, McNemar's test for correlated samples) and in establishing an accurate diagnosis. Ruano et al.78 proposed that the improved performance in detection of some features of skeletal dysplasias by 3D-HCT when compared with ultrasound could be attributed to 3D-HCT images being examined by both a radiologist and a geneticist, whereas ultrasound examinations were performed and analyzed essentially by a sonologist. It remains to be determined if the type of technology, the team approach, the difference in clinical skills, or a combination of all these factors, are ultimately responsible for the differences observed. Regardless of the cause, one way to minimize biases in the interpretation of cases of skeletal dysplasias examined by ultrasound would be to take advantage of 3D-US and information technology (e.g. acquisition and storage of volumes and the possibility of transmitting the files remotely using a fast Internet connection) to have cases re-examined at centers specialized in the diagnosis of skeletal dysplasias. This approach would maximize the diagnostic potential of 3D-US in the clinical setting by ensuring that physicians skilled in the differential diagnosis of skeletal dysplasias can examine the volume datasets. In addition, referral of cases to institutions appropriately equipped and with expertise in prenatal diagnosis would allow studies to be conducted to answer the very questions raised by the current study. It is expected that, as more prenatal diagnostic centers incorporate 3D-US into clinical practice, proficiency in the reconstruction of skeletal structures, as well as the diagnostic accuracy, are likely to improve. Before embracing the use of 3D-HCT, one must have a clear understanding of the goals of diagnostic imaging in the prenatal investigation of skeletal dysplasias: 1) to narrow the differential diagnosis of skeletal dysplasias so that appropriate confirmatory molecular tests can be selected; 2) to predict lethality; and 3) to identify the fetus with a skeletal dysplasia early enough in pregnancy so that the diagnostic workup can be completed before the limit of fetal viability. 3D-HCT will expose the fetus to some degree of radiation, with the potential for long-term harmful effects86, 87. As the number of centers using 3D-US increases, we look forward to the publication of larger series reporting on the accuracy of the combination of 2D-US and 3D-US for the diagnosis of skeletal dysplasias. In our opinion, ultrasound will remain the primary modality for evaluation of the fetus affected by skeletal dysplasias, and 3D-HCT could have a role in cases where the information provided by 3D-US is insufficient for counseling and management. The final diagnoses in the study of Ruano et al.78 were established by postnatal clinical and radiological findings. While this is the standard today, a definitive diagnosis can be established for a growing number of skeletal dysplasias, including the ones described in this study, using molecular and/or biochemical tests. For example, the differential diagnosis of achondroplasia at birth includes severe hypochondroplasia, cartilage hair hypoplasia (metaphyseal chondrodysplasia, McKusick type), and pseudoachondroplasia88. As more than 99% of the patients with achondroplasia have either a Gly380Arg substitution, resulting from a G to A point mutation at nucleotide 1138 of the fibroblast growth factor receptor 3 (FGFR3) gene, or a G to C point mutation at nucleotide 113889, a definitive molecular diagnosis is possible in the majority of cases90. Osteogenesis imperfecta type II is caused by mutations in either the COL1A1 or COL1A2 gene, resulting in abnormal molecular constitution of pro-collagen type I91-93. Diagnosis can be confirmed by biochemical analysis of collagen (collagen screening) and, if the results are equivocal, DNA sequencing of COL1A1 and COL1A294. Rhizomelic chondrodysplasia punctata (RCDP) is a genetically heterogeneous disorder, with three types (types 1, 2 and 3) and an extensive differential diagnosis, including X-linked recessive chondrodysplasia punctata 1 (CDPX1), warfarin embryopathy, X-linked dominant chondrodysplasia punctata (CDPX2), and chondrodysplasia punctata tibial-metacarpal type95. The most common form is type 1, which is caused by mutations in the PEX7 gene (L292X, G217R, and A218V)95-98. These three mutations can be detected in 60% of the cases, whereas 95% of the mutations can be identified by DNA sequencing of the entire PEX7 gene. RCDP types 2 and 3 are inherited in an autosomal recessive manner and are rarer than RCDP type 1. RCDP type 2 is caused by deficiency of the enzyme dihydroxyacetone phosphate acyltransferase, whereas type 3 is caused by deficiency of the peroxysomal enzyme alkyl-dihydroxyacetone phosphate synthase. In both cases, the diagnosis can be confirmed by measurement of the specific enzyme activity in cultured skin fibroblasts95. For a more detailed list of biochemical and molecular tests for the various forms of chondrodysplasia punctata, the reader is referred to the GeneReviews website (http://www.genetests.org/profiles/rcdp). Thus, we suggest that future studies of skeletal dysplasias by 3D-US or other diagnostic imaging modalities include a combination of imaging, histology and molecular techniques for final diagnosis75, whenever the molecular basis for the disorder is known.

BackgroundMutations in the COL2A1 gene cause type II collagenopathies characterized by skeletal dysplasia with a wide spectrum of phenotypic severity. Most COL2A1 mutations located in the triple-helical region, and the glycine to bulky amino acid substitutions (e.g., glycine to serine) in the Gly-X-Y repeat were identified frequently. However, the same COL2A1 mutations are associated with different phenotypes and the genotype-phenotype relationship is still poorly understood. Therefore, the studies of more patients about the recurrent mutations in COL2A1 will be needed for further research to provide more comprehensive clinical and genetic data. In this paper, we report a rare recurrent c.G1636A (p.G546S) mutation in COL2A1 associated with different metaphyseal changes in a Chinese family.Case presentationThe proband (III-3) was the second child of the family with skeletal dysplasia. She was 2 years and 3 months old with disproportional short stature, short neck, pectus carinatum, genu varum, bilateral pes planus, and obvious waddling gait. Notably, she displayed severe metaphyseal lesions, especially typical “dappling” and “corner fracture” appearance, whereas no particular metaphyseal involvement was detected in the proband’s mother (II-3) and elder sister (III-2) in the family. We identified a heterozygous mutation (c.1636G > A) in COL2A1 in the three patients, causing the substitution of glycine to serine in codon 546. Although the same mutation has been reported in two previous studies, the phenotypes of the previous patients were different from those of our patients, and the characteristic “dappling” and “corner fracture” metaphyseal abnormalities were not reported previously.ConclusionsIn this study, we identified a c.G1636A (p.G546S) mutation in the COL2A1 associated with different metaphyseal changes, which was never reported in the literature. Our findings revealed a different causative amino acid substitution (glycine to serine) associated with the “dappling” and “corner fracture” metaphyseal abnormalities, and may provide a useful reference for evaluating the phenotypic spectrum and variability of type II collagenopathies.

Evolving molecular techniques used in the clinical laboratory are becoming increasingly important across nearly all fields of medicine. An increased understanding of carcinogenesis and the use of targeted cancer therapies has resulted in a demand for new types of molecular oncology test to help in cancer diagnosis and as tools to predict response to targeted therapeutics for cancer patients. Understanding the need for and the function of these emerging molecular oncology tests by both clinicians and laboratorians is often problematic. Although many of these molecular testing techniques and strategies are relatively new to oncology, similar testing has been performed in the field of infectious diseases for many years and is now widely accepted and understood. Recognizing the parallels between the molecular testing that is now standard for infectious diseases and testing being introduced to aid in the care of cancer patients will accelerate the acceptance, implementation and correct utilization of molecular assays for oncology.

To analyze genetic causes of skeletal system abnormalities diagnosed by prenatal sonography and to establish a diagnostic protocol with regard to extended genetic testing in this group of patients. This prospective observational cohort study included all singleton pregnancies with a sonographic abnormality of the skeletal system evaluated in a single ultrasound department during a 1-year period (2019). Fetuses underwent routine genetic testing by chromosomal microarray analysis (CMA) supplemented with polyploidy testing, and those with either a normal result or an abnormal result not consistent with the observed phenotype underwent exome sequencing (ES). Interpretation of variants was discussed by a panel of specialists to identify pathogenic/likely pathogenic variants. The study group comprised 55 fetuses. A chromosomal abnormality consistent with the observed phenotype was detected in 24 (43.6%) cases. After exclusions, 26 (47.3%) cases underwent further molecular testing by ES, of which 18 (69.2%) were classified as having abnormal ES results, thus increasing the diagnostic yield by a further 18 (32.7%) cases and giving an abnormal genetic test result in 42/55 (76.4%) fetuses overall. Pathogenic or likely pathogenic sequence variants in 14 different genes were detected across 18 fetuses. Seven genes are already listed in the International Skeletal Dysplasia Society Nosology and seven are not typically found to be causal for skeletal dysplasias and are not listed in the Nosology. In fetuses with skeletal system anomalies, chromosomal abnormality was the most common genetic diagnosis. Exome sequencing increased the diagnostic yield over that of CMA and polyploidy testing. Fetuses with skeletal abnormalities should undergo extended genetic testing following routine testing, as many genetic anomalies responsible for skeletal defects may otherwise be missed. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Introduction: With over 450 described skeletal dysplasia syndromes, prenatal ultrasound findings suggestive of skeletal dysplasia often have a wide differential diagnosis, and most accurate diagnoses are often made through molecular genetic testing. Previous studies have analyzed diagnostic yield of certain prenatal genetic testing methodologies, but there are limited data comparing relative detection rates in cases of suspected skeletal dysplasia. Our study aimed to compare diagnostic yields of available prenatal genetic testing options in suspected skeletal dysplasia cases. Methods: We conducted a multicenter retrospective chart review of 118 cases with ultrasound findings suggestive of skeletal dysplasia over 10 years. Fetal biometry and genetic testing were analyzed for diagnostic accuracy. Theoretical diagnostic yields for various testing methods were also evaluated. Results: Among the 99 individuals who underwent genetic testing, 52 received a molecular diagnosis. Skeletal dysplasia panels and exome sequencing could detect 96% of the syndromes, while single-gene noninvasive prenatal testing could detect 51.9%. In 7.69% of molecularly confirmed cases, ultrasonographic suspicion was incorrect compared to molecular diagnoses. Conclusion: Our findings highlight the crucial role of diagnostic molecular testing in accurately diagnosing suspected skeletal dysplasia, determining recurrence risk, and providing family guidance.

Paediatric survivors beyond infancy with Stüve-Wiedemann syndrome – A case series from the West Midlands, UK

Molecular testing identifies patients with advanced non-small cell lung cancer (NSCLC) who may benefit from targeted therapy or immunotherapy (i.e., immune checkpoint inhibitor treatment for patients with high tumor mutational burden (TMB), microsatellite instability-high or mismatch repair-deficient tumors). Current guidelines state that molecular testing should be conducted at the time of initial diagnosis and tumor progression on targeted therapy. In real-world clinical practice in the United States (US), molecular testing is often not conducted or happens late in the diagnostic journey, resulting in delayed or inappropriate treatment. Herein, we review the rationale for molecular testing in advanced NSCLC, along with best-practice guidelines based on published recommendations and our own clinical experience, including a case study. We propose three strategies to optimize molecular testing in newly diagnosed patients with advanced NSCLC: (I) pulmonologists, interventional radiologists, or thoracic surgeons order molecular tests as soon as advanced NSCLC with an adenocarcinoma component is suspected; (II) liquid biopsies conducted early in the diagnostic pathway; and (III) pathologist-directed reflex testing, as conducted in other areas of oncology. To help facilitate these strategies, we outline our recommendations for optimal sample collection techniques and stewardship. In summary, we believe that implementation of these individual strategies will allow clinicians to effectively leverage available treatment options for advanced NSCLC, reducing the time to optimal treatment and improving patient outcomes.

Genetic Testing for Inherited Retinal Disease

Objectives: The osteochondrodysplasias, or skeletal dysplasias are a genetically heterogeneous group. In the 2006 revision of the International Nosology and Classification of Genetic Skeletal Disorders, 372 different conditions were listed in 37 groups defined by such molecular, biochemical, and/or radiographic criteria. Many of them can present in the prenatal period as demonstrated by ultrasound. We report the prenatal diagnosis of skeletal dysplasias in three centers over 5 years period. Methods: Over 21,000 scans in three centers of prenatal diagnosis were made for suspect of skeletal displasya or routinary scan during 2004–08 period. In the most of cases the invasive prenatal diagnosis (chorionic villus sampling/amniocentesis) was performed and the final diagnosis was sought on the basis of fetopathological examination, radiographic studies and molecular testing. Results: A total of 70 antenatal skeletal dysplasias were diagnosed. Follow-up was in all cases, also if the parents decided to stop the pregnancy. The mean gestational age at US diagnosis was 24 wks (12–35 wks). The lethal skeletal dysplasias were diagnosed in the second trimester, instead the diagnosis of limb reduction was possible in the first trimester. Were diagnosed 31 cases of skeletal dysplasia (44,2%), 24 cases of limb reduction (34,2%), arthrogryposis 5 cases (7,1%), amniotic band lesion 5 cases, unexplained skeletal 5 cases (without diagnosis), dysplasia/limb defect 5 cases. A correct antenatal diagnosis was made in 55 cases (78,5%). Conclusion: A specific prenatal diagnosis is not possible in 20/30% of the cases. The diagnosis on the basis of specific pathology is made in a large period of the pregnancy (12–35wks). For an immediate management, assessment of prognosis (95%) is of more value by US plus molecular diagnosis. The definitive diagnosis is made postnatally based on clinical, radiographic, CT criteria and molecular analysis.

The International Society for Neonatal Screening (ISNS) recognises six different geographical regions [...]

Genetic factors are considered to be the main factors leading to fetal skeletal dysplasia (SD), and chromosomal microarray analysis (CMA) has been used clinically for the detection of SD fetuses. At present, whole exome sequencing (WES) has been applied in SD fetuses, but there is still a lack of data accumulation. The aim of this study is to perform sequential prenatal diagnosis for fetuses with SD indicated by ultrasound and to explore the clinical value of CMA followed by WES. From January 2019 to May 2024, 147 fetuses with SD were detected by prenatal ultrasound screening. After the collection of amniotic fluid or abortive tissue, CMA was performed first, then WES was performed in the cases with a negative CMA result. 147 cases accepted the prenatal CMA test, and 23 cases were reported to have chromosomal abnormalities, including 9 cases of chromosomal aneuploidies, 11 cases of pathogenic copy number variants, and 3 cases of likely pathogenic copy number variants. The detection rate of chromosomal abnormalities by the prenatal CMA test was 15.6% (23/147). 58 cases with negative results of CMA underwent WES, and 21 genes with pathogenic/likely pathogenic variants were detected in 21 cases, including FGFR3, COL2A1, COL1A1, COL1A2, RUNX2, LMX1B, GLI3, SHOX, ALPL, and DYNC2H1. The rate of abnormal prenatal WES was 36.2% (21/58). In the subgroup analysis of the SD phenotype, the detection rate of chromosomal abnormalities in isolated SD fetuses was 7.7% (7/91), which was significantly lower than that in SD fetuses combined with other system abnormalities (28.6%, 16/56) (p = 0.001). The detection rate of monogenic abnormalities in short long bones with other skeletal abnormalities was 62.5% (10/16), which was higher than that in short long bones with non-skeletal abnormalities 10.5% (2/19), and the difference was statistically significant (p = 0.003). SD is mostly caused by monogenic abnormalities, and prenatal WES has significantly improved the detection rate of SD fetuses. The prenatal WES can be used as an important molecular genetic testing method combined with CMA in the sequential prenatal diagnosis of SD fetuses.

ObjectiveSkeletal dysplasias, caused by genetic mutations, are a heterogenous group of heritable disorders affecting bone development during fetal life. Stickler syndrome, one of the skeletal dysplasias, is an autosomal dominant connective tissue disorder caused by abnormal collagen synthesis owing to a genetic mutation in COL2A1. Case reportWe present the case of a 38-year-old multipara woman whose first trimester screening showed a normal karyotype. However, the bilateral femur and humerus length symmetrically shortened after 20 weeks. Next-generation sequencing for mutations in potential genes leading to skeletal dysplasia detected a novel de novo mutation (c.1438G > A, p.Gly480Arg) in COL2A1, causing Stickler syndrome type 1. This pathogenic mutation might impair or destabilize the collagen structure, leading to collagen type II, IX, and XI dysfunction. ConclusionWe identified a novel de novo mutation in COL2A1 related to the STL1 syndrome and delineated the extent of the skeletal dysplasia disease spectrum.

Objectives: Most times in the medical practice, when we have a case of bone fracture, the patient is sent to the Orthopedic Department in order to treat locally the bone fracture with bone consolidation, without thinking at other diseases, of which the patient could suffer from and which in fact represent the real cause of the fracture, exception making the women at menopause, which make frequent fractures on background of osteoporosis and the cancers with different localizations complicate with bone metastasis, in these situations the fractures appear on pathologic bone and have a reserved prognosis. We should investigate further for other pathologies in order to find the real cause of the fracture. Methods: Present the case of a young girl aged 19, comes for a consultation with her mother with a complaint of fatigue, loss of appetite, lack of concentration and attention at school, getting tired easily after minimal physical and intellectual effort, the patient also mentions that about eight months ago she sustained a minor trauma to her left forearm which resulted in a fracture, which was then followed by a fracture of the radius and resulted in her being referred to the orthopedics department where her arm had to be fitted with metal rods. The principal signs was: bone deformation, bone shortening, thin bones, abnormally fragile bones, small muscles, joints and weak tendons, formation of thick scars, small somatic conformation, defective dentition (incomplete dentition , the teeth was damaged, the teeth falled quickly),the cornea was transparent blue(blue sclera) and also her mother had blue sclera. The molecular genetic test was used for clinic diagnosis confirmation and releaved mutations in COL1 A1 and COL1 A2 genes responsabile of sintesis of type I procollagen and confirmed the disease osteogenesis imperfecta. Results: The case of the fracture of the forearm was a very rare genetic disease - osteogenesis imperfecta- a congenital autosomal dominance. A.D. illness and occur even if only one parent transmits the effected gene. As in this case the daughter inherited the disease from her mother. Conclusions: Initially the case appeared to be a trivial case with a simple forearm bone fracture./Subsequently detailed physical examination revealed clinical signs such as somatic changes dentition and more importantly blue sclera pointing us towards the extremely rare disease osteogenesis imperfecta / An examination of the patient’s mother revealed the same signs, confirming the patient had inherited the autosomal dominant disease from her mother./Starting from a simple fracture and some nonspecific clinical symptoms, the final diagnosis was an unexpected surprise to finally discover a hereditary disease with autosomal dominant transmission which is extremely rare - osteogenesis imperfecta. This clinical case should point out that sometimes when a simple fracture is discovered there may be previously unknown underlying disease which may have contributed to the injury and fractures can also be caused by other bone disease./ The molecular genetic test was used for clinic diagnosis confirmation and releaved mutations in COL1 A1 and COL1 A2 genes responsabile of sintesis of type I procollagen and confirmed the disease osteogenesis imperfecta.