Thanatophoric Dysplasia Research Articles

Genetically confirmed thanatophoric dysplasia with fibroblast growth factor receptor 3 mutation

Thanatophoric dysplasia (TD), the most common lethal skeletal dysplasia, is a de novo genetic disease caused by a mutation in the fibroblast growth factor receptor 3 (FGFR3) gene. “Thanatophoric” means “dead bearing” in Greek. Because FGFR3 is the main modulator of bone maturation, typical features of TD include short extremities, curved femur, clover-leaf skull, small narrow chest, and platyspondyly. TD can be classified into two subgroups according to the morphologic findings, with prominent curved femur suggesting type I TD (TD 1) and with marked clover-leaf skull and relatively straight long bones, favoring type II TD (TD 2). However, considering the genetic profiles, TD 1 and TD 2 could be confidently delineated. Here, we report five genotype-phenotype correlated autopsy cases of TD. Five cases had stigmata of TD on antenatal ultrasonography. Terminations were done at gestational age 16 to 28weeks, after family consultation. In autopsy, all fetuses showed short limbs and clover-leaf skull. The microscopic examination of the bones showed disorganized growth plate, consistent with TD. However, some differences existed in gross and microscopic findings between cases. In genetic analyses, three cases revealed missense mutation of Y373C, while the remaining two cases had missense mutation of S371C and S249C each. They were hot spot mutations of TD 1. A correlation between genotype and phenotype was not apparent due to the limited number of the cases. Therefore, a molecular work up to identify the mutation of FGFR3 is indispensable for TD diagnosis in the era of precision medicine for genetic consultation and future targeted therapy.

Mild achondroplasia/hypochondroplasia with acanthosis nigricans, normal development, and a p.Ser348Cys FGFR3 mutation

Pathogenic allelic variants in the fibroblast growth factor receptor 3 (FGFR3) gene have been associated with a number of phenotypes including achondroplasia, hypochondroplasia, thanatophoric dysplasia, Crouzon syndrome with acanthosis nigricans (Crouzonodermoskeletal syndrome), and SADDAN (severe achondroplasia with developmental delay and acanthosis nigricans). Crouzon syndrome with acanthosis nigricans is caused by the pathogenic variant c.1172C>A (p.Ala391Glu) in the FGFR3 gene. The p.Lys650Thr pathogenic variant in FGFR3 has been linked to acanthosis nigricans without significant craniofacial or skeletal abnormalities. Recently, an infant with achondroplasia and a novel p.Ser348Cys FGFR3 mutation was reported. We describe the clinical history of an 8-year-old child with a skeletal dysplasia in the achondroplasia-hypochondroplasia spectrum, acanthosis nigricans, typical development, and the recently described p.Ser348Cys FGFR3 mutation.

Metacarpal Bone Plane Examination by Ultrasonography for the Diagnosis of Fetal Forearm and Hand Deformity

We explored the value of the metacarpal bone plane in screening for serious fetal forearm and hand deformities, excluding simple polydactyly and dactylion deformity, by ultrasonographic examination. Observed the second to fifth metacarpal bone plane of fetuses in 20,139 pregnant women at a gestational age of 16 to 30 weeks in The International Peace Maternity & Child Health Hospital of China Welfare Institute (IPMCH). There was a total 138 cases of fetal forearm and/or hand deformity among the 20,139 pregnant women. Of these, 134 cases were diagnosed, 4 cases were not diagnosed, and 1 case was misdiagnosed. Among the 134 diagnosed cases, there were 19 cases of hand absence, 5 cases of cleft hand, 13 cases of ectrodactyly, 26 cases of radius absence, 9 cases of forearm and hand dysplasia, 55 cases of thanatophoric dysplasia, 6 cases of wrist joint dysplasia, and 1 case of forearm amputation deformity. The deformity rate was 0.76%, the diagnostic coincidence rate was 99.97%, the sensitivity was 97.10%, the specificity was 99.99%, and the false negative rate was 2.9%. As such, careful observation of the metacarpal bone plane can be used increase the diagnosis rate of fetal forearm and hand deformity.

Perinatal imaging findings and molecular genetic analysis of thanatophoric dysplasia type 1 in a fetus with a c.2419T>G (p.Ter807Gly) (X807G) mutation in FGFR3

ObjectiveWe present perinatal imaging findings and molecular genetic analysis of thanatophoric dysplasia type I (TD1) in a fetus. Case ReportA 28-year-old woman was referred for genetic counseling at 22 weeks of gestation because of abnormal prenatal ultrasound findings. Level II ultrasound examination revealed a narrow chest, shortened and curved long limbs, protrusion of the abdomen, and macrocephaly. A tentative diagnosis of TD1 was made. After genetic counseling, the pregnancy was terminated and a malformed fetus was delivered. Postnatal radiography findings were consistent with the diagnosis of TD1, with additional findings of short ribs, platyspondyly, and horizontal acetabular roofs. Molecular genetic analysis using umbilical cord tissue revealed a heterozygous mutation of c.2419T>G (p.Ter807Gly) (X807G) in the fibroblast growth factor receptor 3 gene (FGFR3). ConclusionA second-trimester fetus with a heterozygous c.2419T>G mutation in FGFR3 may present characteristic ultrasound and X-ray findings of TD1.

Pathophysiological analyses of periventricular nodular heterotopia using gyrencephalic mammals.

Although periventricular nodular heterotopia (PNH) is often found in the cerebral cortex of people with thanatophoric dysplasia (TD), the pathophysiology of PNH in TD is largely unknown. This is mainly because of difficulties in obtaining brain samples of TD patients and a lack of appropriate animal models for analyzing the pathophysiology of PNH in TD. Here we investigate the pathophysiological mechanisms of PNH in the cerebral cortex of TD by utilizing a ferret TD model which we recently developed. To make TD ferrets, we electroporated fibroblast growth factor 8 (FGF8) into the cerebral cortex of ferrets. Our immunohistochemical analyses showed that PNH nodules in the cerebral cortex of TD ferrets were mostly composed of cortical neurons, including upper layer neurons and GABAergic neurons. We also found disorganizations of radial glial fibers and of the ventricular lining in the TD ferret cortex, indicating that PNH may result from defects in radial migration of cortical neurons along radial glial fibers during development. Our findings provide novel mechanistic insights into the pathogenesis of PNH in TD.

A Rare Forensic Autopsy Case Report of Thanatophoric Dysplasia Type I

Thanatophoric dysplasia (TD) is a rare disease but commonly found in lethal neonatal skeletal dysplasia, which is caused by pR248C mutation in the fibroblast growth factor receptor 3 (FGFR3) gene. The incidence is found 1 in 15, 000-40, 000 births. There are two types including type I and type II by primarily determining skull and femur shape. TD type I found bowed femurs but not commonly found cloverleaf-shaped skull while TD type II found cloverleaf skull but femur was straight. Present report reveals a case of forensic autopsy of male death fetus in utero, which was diagnosed to be TD type I where large head with prominent forehead bones (frontal bossing), depressed nasal bridge, mesomelia of legs, platyspondyly, curved of both humeri and femurs, and lung hypoplasia. Femoral epiphyseal growth plate retardation and disorganization was found microscopically.

Thanatophoric Dysplasia; a Rare Case Report on a Congenital Anomaly

The rare form of skeletal dysplasia is thanatophoric dysplasia. The meaning for thanatophoric dysplasia is death bearing which is derived from Greek word. It occurs 1in 20,000 to 50,000. It is mainly due to mutations in the fibroblast growth factor receptor 3gene. Features of thanatophoric dysplasia are frontal bossing, prominent eyes, narrow thorax, protruded abdomen and bowed legs. The knowledge about this condition is useful in the fields of Anatomy, Paediatrics, Obstetrics and Gynaecology, Ultrasonagraphy and Genetics, for future research purpose.

Thanatophoric Dysplasia: A Systemic Review of Case Reports

Thanatophoric Dysplasia: A Systemic Review of Case Reports

Thanatophoric Dysplasia Detected During Prenatal Period

Thanatophoric Dysplasia Detected During Prenatal Period

Thanatophoric dysplasia: possibilities of early prenatal ultrasound diagnosis

We reviewed cases of early prenatal diagnosis of thanatophoric dysplasia (TD). Usually ТD is diagnosed at ultrasonic in the second-trimester scan. At first trimester the sonographic traditional signs of TD meet rarely. Often TD to be associated with increased nuchal translucency at first-trimester screening. TD may not be clearly distinguished from the other skeletal dysplasias in a first trimester. A definite diagnosis can be established by molecular genetic analysis.

Diagnóstico ecográfico prenatal de displasia tanatofórica: a propósito de un caso

Diagnóstico ecográfico prenatal de displasia tanatofórica: a propósito de un caso

EP10.40: Thanatophoric dysplasia – ultrasound findings: report of two cases

EP10.40: Thanatophoric dysplasia – ultrasound findings: report of two cases

A case of antenatal-suspected thanatophoric dysplasia type 1 turning out as rather osteogenesis imperfecta type 2

Case: A 26 year old patient 2 gravida, 0 para was referred to our prenatal diagnosis unit at 22 weeks' gestation because of a previous scan showing strong suspicion of thanatophoric dysplasia type 1. The parents were nonrelated. Family history was unremarkable.

HDAC6 deficiency or inhibition blocks FGFR3 accumulation and improves bone growth in a model of achondroplasia.

Mutations that cause increased and/or inappropriate activation of FGFR3 are responsible for a collection of short-limbed chondrodysplasias. These mutations can alter receptor trafficking and enhance receptor stability, leading to increased receptor accumulation and activity. Here, we show that wildtype and mutant activated forms of FGFR3 increase expression of the cytoplasmic deacetylase HDAC6 (Histone Deacetylase 6) and that FGFR3 accumulation is compromised in cells lacking HDAC6 or following treatment of fibroblasts or chondrocytes with small molecule inhibitors of HDAC6. The reduced accumulation of FGFR3 was linked to increased FGFR3 degradation that occurred through a lysosome-dependent mechanism. Using a mouse model of Thanatophoric Dysplasia Type II (TDII) we show that both HDAC6 deletion and treatment with the small molecule HDAC6 inhibitor tubacin reduced FGFR3 accumulation in the growth plate and improved endochondral bone growth. Defective endochondral growth in TDII is associated with reduced proliferation and poor hypertrophic differentiation and the improved bone growth was associated with increased chondrocyte proliferation and expansion of the differentiation compartment within the growth plate. These findings further define the mechanisms that control FGFR3 accumulation and contribute to skeletal pathology caused by mutations in FGFR3.

Post-mortem cytogenomic investigations in patients with congenital malformations

Congenital anomalies are the second highest cause of infant deaths, and, in most cases, diagnosis is a challenge. In this study, we characterize patterns of DNA copy number aberrations in different samples of post-mortem tissues from patients with congenital malformations. Twenty-eight patients undergoing autopsy were cytogenomically evaluated using several methods, specifically, Multiplex Ligation-dependent Probe Amplification (MLPA), microsatellite marker analysis with a MiniFiler kit, FISH, a cytogenomic array technique and bidirectional Sanger sequencing, which were performed on samples of different tissues (brain, heart, liver, skin and diaphragm) preserved in RNAlater, in formaldehyde or by paraffin-embedding. The results identified 13 patients with pathogenic copy number variations (CNVs). Of these, eight presented aneuploidies involving chromosomes 13, 18, 21, X and Y (two presented inter- and intra-tissue mosaicism). In addition, other abnormalities were found, including duplication of the TYMS gene (18p11.32); deletion of the CHL1 gene (3p26.3); deletion of the HIC1 gene (17p13.3); and deletion of the TOM1L2 gene (17p11.2). One patient had a pathogenic missense mutation of g.8535C>G (c.746C>G) in exon 7 of the FGFR3 gene consistent with Thanatophoric Dysplasia type I. Cytogenomic techniques were reliable for the analysis of autopsy material and allowed the identification of inter- and intra-tissue mosaicism and a better understanding of the pathogenesis of congenital malformations.

Valoración ecográfica fetal en displasia esquelética, a propósito de un caso de displasia tanatofórica

Se presenta el caso de una gestante de 30 semanas con feto afectado por displasia tanatofórica (TD) tipo I, quien fue remitida a la Unidad de Medicina Materno Fetal, Hospital Nacional Daniel Alcides Carrión, Callao, Perú, por sospecha de displasia esquelética. En la ultrasonografía se encontraron signos característicos de TD, con marcadores asociados con alto riesgo de letalidad. A propósito del caso sugerimos algunas recomendaciones para la evaluación ultrasonográfica ante la sospecha de casos de displasia esquelética, como una estrategia de acercamiento al diagnóstico.

Thanatophoric Dysplasia

Thanatophoric Dysplasia (TD) is a severe skeletal dysplasia that is lethal in the neonatal period. There are two defined TD subtypes which have been classified clinically. The incidence is approximately 1/20,000 to 1/50,000. Type I TD being more frequent than Type II. Most individuals with TD die within the first few hours.This condition has characteristic sonographic features detected antenatally by midgestation, although distinction from other short-limbed dysplasia syndromes may be difficult. We report a case of type I TD with typical clinicoradiological features who succumbed within one hour of life.J Nepal Paediatr Soc 2015;35(3):304-306.

Thanatophoric dysplasia: A review

Thanatophoric dysplasia is a well-known cause of potentially lethal short-limbed dwarfism in the newborn. The diagnosis is usually made by the recognition of characteristic radiological changes and confirmed at autopsy by demonstration of specific morphological and histological changes in the brain. This review is based upon the author's personal experience and archived data of 19 cases and concerns the clinical and radiographic manifestations, autopsy findings, molecular pathogenesis and the approach to antenatal diagnosis.

Approach to the diagnosis of skeletal dysplasias: Experience at a center with limited resources.

A fetus with skeletal disorder poses diagnostic challenges in a resource-poor setting with limited management options. The objective of the study was to develop a step-by-step approach for the diagnosis of skeletal dysplasia in light of the limited resources available. An algorithmic approach was used. The assessment for lethality was the first step, followed by the evaluation for fractures. In cases without evidence of fracture, severe constriction of thorax or associated polydactyly were searched for. In cases without severe thoracic constriction, the severity of micromelia was evaluated. After delivery, fetal examination was done to ascertain the etiology. During the 6-year period, 41 cases with shortened long bones were fully evaluated. Lethality was suspected in 30 cases. Fracture and beading were present in eight cases, and severe thoracic constriction with polydactyly was observed in seven cases. Mild micromelia was seen in 19 cases and severe micromelia in 7 cases. Among lethal skeletal dysplasias, thanatophoric dysplasia was most common (six cases). Among nonlethal skeletal dysplasias, achondroplasia was seen in eight cases. Lethality of skeletal dysplasia could be predicted on prenatal ultrasound with 100% accuracy. The step-by-step approach was helpful to characterize skeletal dysplasias. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:529-539, 2016.

Identification of a novel insertion mutation in FGFR3 that causes thanatophoric dysplasia type 1.

Thanatophoric dysplasia is a type of short-limbed neonatal dwarfism that is usually lethal in the perinatal period. It is characterized by short limbs, a narrow, bell-shaped thorax, macrocephaly with a prominent forehead, and flattened vertebral bodies. These malformations result from autosomal dominant mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. In this report, we describe a novel FGFR3 insertion mutation in a fetus with shortened limbs, curved femurs, and a narrow thorax. The diagnosis of thanatophoric dysplasia type 1 was suspected clinically, and FGFR3 sequencing showed a c.742_743insTGT variant, which predicts p.R248delinsLC. In vivo studies in zebrafish demonstrated that this mutation resulted in the overexpression of zebrafish Fgfr3, leading to the over-activation of downstream signaling and dorsalized embryos. To date, no insertions or deletions in FGFR3 have been reported to cause thanatophoric dysplasia types 1 or 2; therefore, this represents the first report to describe such a mutation. © 2016 Wiley Periodicals, Inc.