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Das S, Sharma C, Gothwal M, Tada N. Whole exome sequencing, clinical exome or targeted gene panels: what to choose for suspected lethal skeletal dysplasia (short rib thoracic dysplasia type IV). BMJ Case Rep 2022; 15:e251118. [PMID: 36123010 PMCID: PMC9486215 DOI: 10.1136/bcr-2022-251118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Lethal skeletal dysplasias (SDs) are a heterogeneous group of rare but important genetic disorders characterised by abnormal growth and development of bone and cartilage. The phenotypic variation of SD highlights the complex aetiology for this group of disorders. Short rib polydactyly syndrome (SRPS) types I-IV are a group of rare congenital autosomal recessive types of SD.We report a case of a non-consanguineous couple whose two successive pregnancies were diagnosed with multiple congenital anomalies in fetuses suggestive of lethal SD (likely SRPS type IV) at 24 and 19 weeks period of gestation, respectively. Pregnancy was terminated, and the whole exome sequencing of the abortus for genetic analysis in the second pregnancy confirmed an autosomal recessive type of short rib thoracic dysplasia-4 (SRTD-4) also called SRPS in homozygous condition. Our case is unique as it was also associated with cystic hygroma which is a rare association with SRPS/SRTD-4.
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Affiliation(s)
- Shreya Das
- Obstetrics and Gynaecology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
| | - Charu Sharma
- Obstetrics and Gynaecology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
| | - Meenakshi Gothwal
- Obstetrics and Gynaecology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
| | - Nayan Tada
- Paediatrics, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
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Farooq M, Khan AW, Kim MS, Choi S. The Role of Fibroblast Growth Factor (FGF) Signaling in Tissue Repair and Regeneration. Cells 2021; 10:cells10113242. [PMID: 34831463 PMCID: PMC8622657 DOI: 10.3390/cells10113242] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 11/10/2021] [Accepted: 11/16/2021] [Indexed: 02/06/2023] Open
Abstract
Fibroblast growth factors (FGFs) are a large family of secretory molecules that act through tyrosine kinase receptors known as FGF receptors. They play crucial roles in a wide variety of cellular functions, including cell proliferation, survival, metabolism, morphogenesis, and differentiation, as well as in tissue repair and regeneration. The signaling pathways regulated by FGFs include RAS/mitogen-activated protein kinase (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)–protein kinase B (AKT), phospholipase C gamma (PLCγ), and signal transducer and activator of transcription (STAT). To date, 22 FGFs have been discovered, involved in different functions in the body. Several FGFs directly or indirectly interfere with repair during tissue regeneration, in addition to their critical functions in the maintenance of pluripotency and dedifferentiation of stem cells. In this review, we summarize the roles of FGFs in diverse cellular processes and shed light on the importance of FGF signaling in mechanisms of tissue repair and regeneration.
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Affiliation(s)
- Mariya Farooq
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea; (M.F.); (A.W.K.); (M.S.K.)
| | - Abdul Waheed Khan
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea; (M.F.); (A.W.K.); (M.S.K.)
| | - Moon Suk Kim
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea; (M.F.); (A.W.K.); (M.S.K.)
| | - Sangdun Choi
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea; (M.F.); (A.W.K.); (M.S.K.)
- S&K Therapeutics, Ajou University Campus Plaza 418, 199 Worldcup-ro, Yeongtong-gu, Suwon 16502, Korea
- Correspondence:
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Abstract
PURPOSE OF REVIEW The implementation of palliative care at birth has led to a significant rise in the number of couples who choose to continue with pregnancies complicated by life-limiting malformations (LLMs). Prenatal counselling and appropriate antenatal/perinatal management in these cases are poorly studied and may pose significant challenges. The purpose of this review is to outline specific obstetric risks and to suggest management for mothers who choose to continue with pregnancies with the most common LLMs. RECENT FINDINGS In pregnancies complicated by LLMs where parents opt for expectant management, clinicians should respect parental wishes, whilst openly sharing potential serious maternal medical risks specific for the identified abnormalities. The focus of both antenatal and perinatal care should be maternal wellbeing rather than foetal survival. Follow-up ultrasound examinations and maternal surveillance should be aimed at achieving timely diagnosis and effective management of obstetric complications. A clear perinatal plan, agreed with the couples by a multi-disciplinary team including a foetal medicine specialist, a neonatologist and a geneticist, is crucial to reduce maternal morbidity. SUMMARY This review provides a useful framework for clinicians who face the challenges of counselling and managing cases complicated by LLMs where parents opt for pregnancy continuation.
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Sabir AH, Sheikh J, Singh A, Morley E, Cocca A, Cheung MS, Irving M. Earlier detection of hypochondroplasia: A large single-center UK case series and systematic review. Am J Med Genet A 2020; 185:73-82. [PMID: 33051983 DOI: 10.1002/ajmg.a.61912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 09/10/2020] [Accepted: 09/24/2020] [Indexed: 11/07/2022]
Abstract
Hypochondroplasia (HCH) is a rare autosomal dominant skeletal dysplasia condition caused by FGFR3 mutations leading to disproportionate short stature. Classically HCH presents in toddlers or school-age children, as limb-to-trunk disproportion and is often mild and easily overlooked during infancy. We report experiences from a single-center UK HCH-cohort of 31 patients, the rate of antenatal HCH detection in our cohort (13/31, 41.9%) and describe relevant case-data for this subset of 13 patients. Inclusion criteria were patients with confirmed molecular HCH diagnosis (by age 3 years) and presenting with short long-bones or large head size on antenatal ultrasound scan. We then conducted a systematic literature review using PUBMED and MEDLINE, analyzing patients with HCH and related antenatal findings. Antenatally suspected (with subsequent molecular confirmation) HCH has been reported 15 times in the literature (2004-2019). Key markers (consistent in both groups) included reduced; femur length, humeral length and increased; biparietal diameter and head circumference. HCH is increasingly detected both antenatally and in infancy, contrary to previous descriptions. This is likely due to greater HCH awareness, improved imaging, and easier molecular testing. Thus, one should consider HCH outside the classical presenting period. Studying the natural history of younger patients with HCH is important with the advent of several targeted FGFR3 therapies currently in trials for Achondroplasia, that may soon be trialed in HCH.
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Affiliation(s)
- Ataf H Sabir
- Department of Clinical Genetics, Guy's and St Thomas' NHS Foundation Trust, London, UK.,Department of Clinical Genetics, Birmingham Women's and Children's Hospital NHS Trust & Birmingham Health Partners, Birmingham, UK.,Medical School, University of Birmingham, Birmingham, UK
| | - Jameela Sheikh
- Medical School, University of Birmingham, Birmingham, UK
| | - Ananya Singh
- Medical School, University of Birmingham, Birmingham, UK
| | - Elizabeth Morley
- Department of Trauma and Orthopaedics, The Royal Wolverhampton NHS Trust, Wolverhampton, UK
| | - Alessandra Cocca
- Department of Paediatric Endocrinology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Moira S Cheung
- Department of Paediatric Endocrinology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Melita Irving
- Department of Clinical Genetics, Guy's and St Thomas' NHS Foundation Trust, London, UK
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Mardy AH, Chetty SP, Norton ME, Sparks TN. A system-based approach to the genetic etiologies of non-immune hydrops fetalis. Prenat Diagn 2019; 39:732-750. [PMID: 31087399 DOI: 10.1002/pd.5479] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 04/11/2019] [Accepted: 05/09/2019] [Indexed: 12/11/2022]
Abstract
A wide spectrum of genetic causes may lead to nonimmune hydrops fetalis (NIHF), and a thorough phenotypic and genetic evaluation are essential to determine the underlying etiology, optimally manage these pregnancies, and inform discussions about anticipated prognosis. In this review, we outline the known genetic etiologies of NIHF by fetal organ system affected, and provide a systematic approach to the evaluation of NIHF. Some of the underlying genetic disorders are associated with characteristic phenotypic features that may be seen on prenatal ultrasound, such as hepatomegaly with lysosomal storage disorders, hyperechoic kidneys with congenital nephrosis, or pulmonary valve stenosis with RASopathies. However, this is not always the case, and the approach to evaluation must include prenatal ultrasound findings as well as genetic testing and many other factors. Genetic testing that has been utilized for NIHF ranges from standard chromosomal microarray or karyotype to gene panels and broad approaches such as whole exome sequencing. Family and obstetric history, as well as pathology examination, can yield additional clues that are helpful in establishing a diagnosis. A systematic approach to evaluation can guide a more targeted approach to genetic evaluation, diagnosis, and management of NIHF.
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Affiliation(s)
- Anne H Mardy
- Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, US
| | - Shilpa P Chetty
- Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, US
| | - Mary E Norton
- Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, US
| | - Teresa N Sparks
- Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, San Francisco, CA, US
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Abstract
Achondroplasia is the most common of the skeletal dysplasias that result in marked short stature (dwarfism). Although its clinical and radiologic phenotype has been described for more than 50 years, there is still a great deal to be learned about the medical issues that arise secondary to this diagnosis, the manner in which these are best diagnosed and addressed, and whether preventive strategies can ameliorate the problems that can compromise the health and well being of affected individuals. This review provides both an updated discussion of the care needs of those with achondroplasia and an exploration of the limits of evidence that is available regarding care recommendations, controversies that are currently present, and the many areas of ignorance that remain.
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Affiliation(s)
- Richard M Pauli
- Midwest Regional Bone Dysplasia Clinic, Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, 1500 Highland Ave., Madison, WI, 53705, USA.
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Soo-Kyeong J, Lee N, Bae MH, Han YM, Hee Park K, Byun SY. Chylous Ascites in an Infant with Thanatophoric Dysplasia Type I with FGFR3 Mutation Surviving Five Months. Fetal Pediatr Pathol 2018; 37:363-371. [PMID: 30252581 DOI: 10.1080/15513815.2018.1504843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Thanatophoric dysplasia (TD) results from sporadic de novo mutations in the FGFR3 gene. Upon confirming intrauterine diagnosis of this perinatal disease, pregnancy termination is recommended. There is limited information on the natural history of longer-term survivors with type 1 TD. CASE REPORT A full-term neonate was confirmed via postnatal genetic testing to have type 1 TD. At 28 days, chylous ascites developed. Medium-chain triglyceride use improved the ascites. Cerebral ventriculomegaly worsened throughout life. Death due to respiratory failure occurred at age 5 months. CONCLUSION The chylous ascites in this child with type 1 TD and survival past the neonatal stage suggests that type 1 TD may be accompanied by abnormalities of the lymphatic channels. Moreover, ventriculomegaly can be progressive.
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Affiliation(s)
- Jeon Soo-Kyeong
- a Department of Pediatrics , Pusan National University Children's Hospital , Yangsan , Korea.,b Department of Pediatrics , Pusan National University School of Medicine , Busan , Korea
| | - Narae Lee
- a Department of Pediatrics , Pusan National University Children's Hospital , Yangsan , Korea.,b Department of Pediatrics , Pusan National University School of Medicine , Busan , Korea
| | - Mi Hye Bae
- b Department of Pediatrics , Pusan National University School of Medicine , Busan , Korea.,c Department of Pediatrics , Pusan National University School of Medicine , Yangsan , Korea
| | - Young Mi Han
- a Department of Pediatrics , Pusan National University Children's Hospital , Yangsan , Korea.,b Department of Pediatrics , Pusan National University School of Medicine , Busan , Korea
| | - Kyung Hee Park
- b Department of Pediatrics , Pusan National University School of Medicine , Busan , Korea.,c Department of Pediatrics , Pusan National University School of Medicine , Yangsan , Korea
| | - Shin Yun Byun
- a Department of Pediatrics , Pusan National University Children's Hospital , Yangsan , Korea.,b Department of Pediatrics , Pusan National University School of Medicine , Busan , Korea
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Deng L, Cheung SW, Schmitt ES, Xiong S, Yuan M, Chen Z, Chen L, Sun L. Targeted gene panel sequencing prenatally detects two novel mutations of DYNC2H1
in a fetus with increased biparietal diameter and polyhydramnios. Birth Defects Res 2018; 110:364-371. [PMID: 29359448 DOI: 10.1002/bdr2.1146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/13/2017] [Accepted: 09/27/2017] [Indexed: 12/22/2022]
Affiliation(s)
- Linbei Deng
- Department of Fetal Medicine Unit and Prenatal Diagnosis Center; Shanghai First Maternity and Infant Hospital of Tongji University; Shanghai China
| | - Sau Wai Cheung
- Department of Molecular and Human Genetics; Baylor College of Medicine, One Baylor Plaza; Houston Texas
| | - Eric S. Schmitt
- Department of Molecular and Human Genetics; Baylor College of Medicine, One Baylor Plaza; Houston Texas
| | - Shiyi Xiong
- Department of Fetal Medicine Unit and Prenatal Diagnosis Center; Shanghai First Maternity and Infant Hospital of Tongji University; Shanghai China
| | - Meizhen Yuan
- Department of Fetal Medicine Unit and Prenatal Diagnosis Center; Shanghai First Maternity and Infant Hospital of Tongji University; Shanghai China
| | - Zhonghai Chen
- Beijing Genomics Institute at Shenzhen; Shenzhen Guangdong China
| | - Lei Chen
- Beijing Genomics Institute at Shenzhen; Shenzhen Guangdong China
| | - Luming Sun
- Department of Fetal Medicine Unit and Prenatal Diagnosis Center; Shanghai First Maternity and Infant Hospital of Tongji University; Shanghai China
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Wang L, Takai Y, Baba K, Mikami Y, Saito M, Horiuchi I, Konno R, Takagi K, Seki H. Can biparietal diameter-to-femur length ratio be a useful sonographic marker for screening thanatophoric dysplasia since the first trimester? A literature review of case reports and a retrospective study based on 10,293 routine fetal biometry measurements. Taiwan J Obstet Gynecol 2017; 56:374-378. [DOI: 10.1016/j.tjog.2017.04.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2017] [Indexed: 11/15/2022] Open
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Abstract
Orthopedic surgeons frequently encounter short statured patients. A systematic approach is needed for proper evaluation of these children. The differential diagnosis includes both proportionate and disproportionate short stature types. A proper history and physical examination and judicious use of plain film radiography will establish the diagnosis in most cases. In addition to the orthopedic surgeon, most of these patients will also be evaluated by other specialists, including endocrinologists and geneticists. This article provides an overview of the evaluation of the child with short stature and offers several illustrative examples.
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Affiliation(s)
- Charles T Mehlman
- Division of Pediatric Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center, MLC 2017, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
| | - Michael C Ain
- Department of Orthopaedic Surgery, The Johns Hopkins University, 1800 Orleans street, Baltimore, MD 21287, USA
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Khalil A, Morales-Roselló J, Morlando M, Bhide A, Papageorghiou A, Thilaganathan B. Widening of the femoral proximal diaphysis--metaphysis angle in fetuses with achondroplasia. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2014; 44:69-75. [PMID: 24623391 DOI: 10.1002/uog.13339] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/09/2014] [Accepted: 02/11/2014] [Indexed: 06/03/2023]
Abstract
OBJECTIVES It has recently been reported that fetuses with achondroplasia have a wider than expected femoral proximal diaphysis-metaphysis angle (femoral angle). The aim of this case-control study was to investigate this finding. METHODS Cases with confirmed achondroplasia (n = 6), small-for-gestational-age fetuses (n = 70) and a group of normal fetuses (n = 377) were included in this study. The ultrasound image of the femur was examined by two independent experienced observers blinded to the diagnosis, who measured the femoral angle. These values were converted into multiples of the expected median (MoM), after adjustment for gestational age and femur length. Prevalence of various prenatal ultrasound signs of achondroplasia was determined in affected fetuses. Intra- and interobserver agreement of measurement of femoral angle was assessed using 95% limits of agreement and kappa statistics. RESULTS The femoral angle can be measured accurately by ultrasound, and increases with both increasing gestational age and increasing femur length. The femoral angle-MoM was significantly higher in fetuses with achondroplasia than in the control group (1.36 vs 1.00 MoM, P < 0.001) and in the SGA group (1.36 vs 1.04 MoM, P < 0.001). It measured more than 130° in five of the six cases with achondroplasia (83.3%), which was the most consistent finding other than shortening of the long bones. CONCLUSIONS The femoral angle is wider in fetuses with achondroplasia. This new ultrasound sign appears promising as an additional discriminatory marker when clinicians are faced with a case of short long bones in the third trimester.
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Affiliation(s)
- A Khalil
- Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's University of London, London, UK
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Thanatophoric dysplasia in a dichorionic twin confirmed by genetic analysis at the early second trimester: A case report and literature review. Obstet Gynecol Sci 2014; 57:151-4. [PMID: 24678489 PMCID: PMC3965699 DOI: 10.5468/ogs.2014.57.2.151] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Revised: 09/12/2013] [Accepted: 09/16/2013] [Indexed: 11/29/2022] Open
Abstract
Thanatophoric dysplasia (TD) is caused by mutation of the gene that encodes fibroblast growth factor 3 (FGFR3). Owing to the poor prognosis for TD, prenatal diagnosis is critical to optimal perinatal management. We report here a case of TD in twin pregnancy, which was prenatally diagnosed by DNA analysis following amniocentesis at 15 weeks, and was managed by selective fetal termination. Prenatal ultrasonography and molecular analysis to detect TD-specific mutations enable accurate diagnosis of FGFR3-related TD in utero and appropriate obstetrical management at early gestation during twin pregnancy.
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Detection of a de novo Y278C mutation in FGFR3 in a pregnancy with severe fetal hypochondroplasia: Prenatal diagnosis and literature review. Taiwan J Obstet Gynecol 2013; 52:580-5. [DOI: 10.1016/j.tjog.2013.10.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 06/21/2013] [Indexed: 11/22/2022] Open
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Park KE, Kim SA, Kang MJ, Kim HS, Cho SI, Yoo KW, Kim SY, Lee HJ, Oh SK, Seong MW, Ku SY, Jun JK, Park SS, Choi YM, Moon SY. Successful birth with preimplantation genetic diagnosis using single-cell allele-specific PCR and sequencing in a woman with hypochondroplasia due to FGFR3 mutation (c.1620C>A, p.N540K). Clin Exp Reprod Med 2013; 40:42-6. [PMID: 23614116 PMCID: PMC3630293 DOI: 10.5653/cerm.2013.40.1.42] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 02/13/2013] [Accepted: 02/14/2013] [Indexed: 12/05/2022] Open
Abstract
Hypochondroplasia (HCH) is an autosomal dominant inherited skeletal dysplasia, usually caused by a heterozygous mutation in the fibroblast growth factor receptor 3 gene (FGFR3). A 27-year-old HCH woman with a history of two consecutive abortions of HCH-affected fetuses visited our clinic for preimplantation genetic diagnosis (PGD). We confirmed the mutation in the proband (FGFR3:c.1620C>A, p.N540K), and established a nested allele-specific PCR and sequence analysis for PGD using single lymphocyte cells. We performed this molecular genetic analysis to detect the presence of mutation among 20 blastomeres from 18 different embryos, and selected 9 embryos with the wild-type sequence (FGFR3:c.1620C). A successful pregnancy was achieved through a frozen-thawed cycle and resulted in the full-term birth of a normal neonate. To the best of our knowledge, this is the first report of a successful pregnancy and birth using single-cell allele-specific PCR and sequencing for PGD in an HCH patient.
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Affiliation(s)
- Kyung Eui Park
- Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
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Marquis-Nicholson R, Aftimos S, Love DR. Molecular Analysis of a Case of Thanatophoric Dysplasia Reveals Two de novo FGFR3 Missense Mutations located in cis. Sultan Qaboos Univ Med J 2013; 13:80-7. [PMID: 23573386 DOI: 10.12816/0003199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 09/02/2012] [Accepted: 10/06/2012] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVES Thanatophoric dysplasia (TD) is the most common form of lethal skeletal dysplasia. It is primarily an autosomal dominant disorder and is characterised by macrocephaly, a narrow thorax, short ribs, brachydactyly, and hypotonia. In addition to these core phenotypic features, TD type I involves micromelia with bowed femurs, while TD type II is characterised by micromelia with straight femurs and a moderate to severe clover-leaf deformity of the skull. Mutations in the FGFR3 gene are responsible for all cases of TD reported to date. The objective of the study here was to delineate further the mutational spectrum responsible for TD. METHODS Conventional polymerase chain reaction (PCR), allele-specific PCR, and sequence analysis were used to identify FGFR3 gene mutations in a fetus with a lethal skeletal dysplasia consistent with TD, which was detected during a routine antenatal ultrasound examination. RESULTS In this report we describe the identification of two de novo missense mutations in cis in the FGFR3 gene (p.Asn540Lys and p.Val555Met) in a fetus displaying phenotypic features consistent with TD. CONCLUSION This is the second description of a case of TD occurring as a result of double missense FGFR3 gene mutations, suggesting that the spectrum of mutations involved in the pathogenesis of TD may be broader than previously recognised.
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