De novo variants of dominant monogenic disorders in Vietnam detected by a noninvasive prenatal test: a case series

Background: Noninvasive prenatal tests for monogenic diseases (NIPT-SGG) have recently been reported as helpful in early-stage antenatal screening. Our study describes the clinical and genetic features of cases identified by NIPT-SGG. Materials & methods: In a cohort pregnancy with abnormal sonograms, affected cases were confirmed by invasive diagnostic tests concurrently, with NIPT-SGG targeting 25 common dominant single-gene diseases. Results: A total of 13 single-gene fetuses were confirmed, including Noonan and Costello syndromes, thanatophoric dysplasia, achondroplasia, osteogenesis imperfecta and Apert syndrome. Two novel variants seen were tuberous sclerosis complex (TSC2 c.4154G>A) and Alagille syndrome (JAG1 c.3452del). Conclusion: NIPT-SGG and standard tests agree on the results for 13 fetuses with monogenic disorders. This panel method of screening can benefit high-risk Vietnamese pregnancies, but further research is encouraged to expand on the causative gene panel.

Diagnosis of thanatophoric dysplasia using clinical exome screening

Bone dysplasias are a broad, heterogeneous group of diseases. Thanatophoric dysplasia is a rare bone dysplasia, but it is the most common lethal skeletal dysplasias. The major role in diagnostics plays a high-quality ultrasound examination in the 2nd trimester and the latest methods of genetic testing, including clinical exome testing. Knowing the correct diagnosis is crucial for the future of the fetus and the couple.

A THANATOPHORIC DYSPLASIA TYPE I CASE WITH A FGFR3 P.R248C MUTATION AND SURVIVAL BEYOND THE NEONATAL PERIOD

A Thanatophoric dysplasia, is a severe congenital anomaly which mostly causes stillbirth or death of the affected baby within hours due to respiratory insufficiency. The diagnosis of TD is typically suspected on ultrasound during the second trimester of pregnancy, when severe shortening of the long bones, frontal bossing, flattened vertebrae, and short ribs that result in a narrow thorax and bell-shaped abdomen, can be seen. Here, we present a case with prenatal ultrasonographic findings suggestive of TD, and highlight the patient's postnatal dysmorphic features and typical radiographic findings. The definitive diagnosis of TD type I (TDI) was made postnatally, when molecular genetic analysis revealed the previously described p.R248C mutation in FGFR3. This case is reported due to its relative long life span and the definitive molecular diagnosis that could be made during hospitalization.

A case report on the antenatal three dimensional sonographic features of thanatophoric dysplasia

Thanatophoric dysplasia (TD) is a well-known fatal skeletal dysplasia in fetal life. It can be usually diagnosed by two-dimensional (2D) ultrasonography. However three-dimensional (3D) ultrasonography, a new rapidly available technique, can be a useful addition to 2D ultrasonography for improving the visualization of the abnormalities and giving help when providing counseling to a family regarding the diagnosis and future recurrences. Here, the authors present the first experience in Songklanagarind Hospital in applying 3D ultrasonography in the diagnosis of fetal thanatophoric dysplasia.

Congenital cervical instability in a patient with camptomelic dysplasia

INTRODUCTION

Camptomelic dysplasia (CD) is a rare autosomal dominant skeletal dysplasia classically characterized by bent bones of the extremities, tracheobronchial narrowing, thoracic kyphoscoliosis, and various degrees of phenotypic sex reversal. Most patients die of complications in infancy, although long-term survivors have been reported.

CASE REPORT

We report a case of CD complicated by incomplete ossification of the cervical vertebral pedicles, resulting in congenital cervical instability and kyphosis. Closed reduction was performed, and the patient was fitted with a customized cervical orthosis.

FINDING

He subsequently developed a complete spinal cord injury at the kyphotic level. This underscores the grim prognosis associated with neonatal cervical spinal instability.

Fetal musculoskeletal malformations with a poor outcome: ultrasonographic, pathologic, and radiographic findings

The early and accurate antenatal diagnosis of fetal musculoskeletal malfomations with a poor outcome has important implications for the management of a pregnancy. Careful ultrasonographic examination of a fetus helps detect such anomalies, and a number of characteristic features may suggest possible differential diagnoses. During the last five years, we have encountered 39 cases of such anomalies, and the typical prenatal ultrasonographic and pathologic findings of a number of those are described in this article.

Russell-Silver Syndrome in a Nigerian infant with intrauterine growth retardation

Russell-Silver Syndrome (RSS) is a rare cause of pre-natal dwarfism, associated with recognizable dysmorphic features and limb asymmetry. The propositus was a term infant of unrelated Nigerian parents, whose 35-year-old mother had peri-conceptual haloperidol for schizophrenia. Anthropometric values suggested severe prenatal stunting in a term infant with asymmetric "head sparing" intrauterine growth retardation (IUGR). A syndromic consideration of Russell-Silver dwarfism was subsequently predicated on the distinctive dysmorphic craniofacial features of a triangular facial profile with a broad forehead and hypoplastic mandible, right upper and lower limb rhizomelia, clinodactyly of the little fingers, micro-penis, and (unilateral) cryptochidism. Routine care of a small-for-gestational-age infant was pursued, but postnatal growth remained slow (despite adequate caloric provision) until a parent-pressured discharge at 4 weeks. His subsequent demise was said to have occurred "suddenly" 2 weeks post-discharge. Despite the limitations posed by the local paucity of modern investigative tools for genetic disorders, the current case report underscores the diagnostic reality of RSS in a non-white African population. While emphasizing the need for a high index of diagnostic suspicion for congenital malformations and syndromic causes of IUGR in the African sub-region, we suspect a possible etiologic association of haloperidol embryopathy with RSS in the current case. The characteristic features, differential diagnoses, etiologic postulates/current cytogenetic and molecular genetic findings of RSS are fully reviewed in the discussion.

Prenatal diagnosis and genetic analysis of type I and type II thanatophoric dysplasia

Thanatophoric dysplasia (TD) is one of the most common neonatal lethal skeletal dysplasias. Prenatal sonographic and molecular genetic diagnoses of three cases of TD type I (TD1) and one case of TD type II (TD2) are presented here. Two fetuses of TD1 were characterized by polyhydramnios, macrocephaly, short limbs, a narrow thoracic cage and curved short femora, but without a cloverleaf skull at 27 and 31 weeks' gestation, respectively. The third fetus with TD1 was, however, not associated with macrocephaly, polyhydramnios, chest narrowing and severe femoral bowing on prenatal ultrasound at 18 weeks' gestation. The TD2 fetus was characterized by polyhydramnios, short limbs, a narrow thoracic cage, straight short femora, hydrocephalus and a cloverleaf skull at 24 weeks' gestation. Three-dimensional ultrasound was able to enhance the visualization of thickened, redundant skin folds and craniofacial and limb deformities associated with TD. Molecular analysis of the fibroblast growth factor receptor 3 (FGFR3) gene by restriction enzyme digestion analysis and direct sequencing using cultured amniotic fluid cells or cord blood cells revealed a missense mutation of 742C-->T (Arg248Cys) in all cases with TD1 and a missense mutation of 1948A-->G (Lys650Glu) in the case with TD2. The present report shows that adjunctive applications of molecular genetic analysis of the FGFR3 gene and three-dimensional ultrasound are useful for prenatal diagnosis of TD.

Sonographic and molecular diagnosis of thanatophoric dysplasia type I at 18 weeks of gestation

Thanatophoric dysplasia is the most common type of lethal skeletal dysplasia. It can usually be diagnosed with ultrasound, but differential diagnosis with other osteochondrodysplasias is not always possible. Mutations in the fibroblast growth factor receptor 3 (FGFR3) gene have been demonstrated to cause two distinct subtypes of the disorder. We describe a case of thanatophoric dysplasia type I diagnosed at 18 weeks of gestation by ultrasonography. Genomic DNA obtained by chorionic villus sampling showed a C to G substitution at position 746 in the FGFR3 gene, resulting in a Ser249Cys substitution already known to be associated with type I disease. Implications for perinatal management are discussed.

Bone dysplasia series. Achondroplasia, hypochondroplasia and thanatophoric dysplasia: review and update

The authors summarize the clinical, genetic and histopathologic features, as well as the complications, and radiological diagnosis of 3 related generalized short-limb skeletal dysplasias: achondroplasia, hypochondroplasia and thanatophoric dysplasia. In all of these dysplasias, there is abnormal endochondral ossification, but periosteal ossification is not affected. These 3 relatively common entities are known to be allelic to the same gene: the fibroblast growth factor receptor 3 gene on chromosome 4p. Heterozygous achondroplasia is the most common nonlethal skeletal dysplasia. The distinctive clinical and radiological features allow a precise diagnosis, as there is little variability in the appearance of affected patients. There is also a very evident molecular homogeneity. On histopathology of the growth plate, there is a quantitative decrease in endochondral ossification. Precise prenatal ultrasonographic diagnosis is possible in the third trimester, and sometimes even in the second. Hypochondroplasia is a relatively common, milder form of achondroplasia, which varies within and between families and lacks the neurological complications often seen in achondroplasia of this group. An accurate prenatal ultrasonographic diagnosis is rare. There are milder changes on histology of the growth plate. Thanatophoric dysplasia is the lethal and most severe dysplasia. It has distinct features--mainly short tubular bones and short ribs with platyspondyly--allowing a precise radiologic and prenatal ultrasonographic diagnosis. On histopathology of the growth plate, there is disruption of endochondral ossification.

Camptomelic dysplasia: a case study

Camptomelic dysplasia (CMD) is a congenital short-limb skeletal dysplasia characterized by prenatal bowing of the lower limbs in association with additional anomalies of the tracheobronchial tree or genitourinary tract. Perinatal and early neonatal death from respiratory failure is common. Diagnosis and long-term management of the infant with CMD require a coordinated effort among many specialists. This article presents a general overview of skeletal dysplasias and camptomelic dysplasia. It concludes with a case study illustrating the many problems infants with CMD may have and the complex treatment and follow-up services they require.

Prenatal diagnosis of thanatophoric dysplasia by mutational analysis of the fibroblast growth factor receptor 3 gene and a proposed correction of previously published PCR results

Thanatophoric dysplasia (TD) is the most frequent form of neonatal lethal skeletal dysplasia. Recently. mutations in the fibroblast growth factor receptor 3 (FGFR3) gene that cause two subtypes of this disorder, type I (TDI) and type II (TDII), have been identified. This discovery has now made it possible to make a definite diagnosis of TD by molecular methods. To date, prenatal diagnosis of TD has been accomplished by ultrasonography in the second trimester. However, it is not always possible to distinguish TD fetuses it utero from the other osteochondrodysplasias by ultrasonography or radiography. We report on the prenatal diagnosis of a TD fetus, showing severe shortness of limbs and polyhydramnios, by identification of a mutation in the FGFR3 gene. Genomic DNA was isolated from the amniotic fluid and then subjected to PCR amplification. The common TDI mutation, C-->T transition at nucleotide 742 in the FGFR3 gene, was identified using restriction enzyme analysis. This information was critical in obstetric management decisions later in pregnancy. However, although the mutation responsible for TDI was detected previously, we noticed some inconsistencies in the published PCR results and have proposed a correction.

Molecular, radiologic, and histopathologic correlations in thanatophoric dysplasia

Various mutations in the fibroblast growth factor receptor 3 (FGFR3) gene have recently been reported in thanatophoric dysplasia (TD). We examined the clinical, radiographic, and histologic findings in 91 cases from the International Skeletal Dysplasia Registry and correlated them with the specific FGFR3 mutation. Every case of TD examined had an identifiable FGFR3 mutation. Radiographically, all of the cases with the Lys650Glu substitution demonstrated straight femora with craniosynostosis, and frequently a cloverleaf skull (CS) was demonstrated. In all other cases, the femora were curved, and CS was infrequently present but was occasionally as severe as TD with the Lys650Glu substitution. Histopathologically, all of the cases shared similar abnormalities, but cases with the Lys650Glu substitution had better preservation of the growth plate. Cases with the Tyr373Cys substitution tended to have more severe radiographic manifestations than the Arg248Cys cases, but there was overlap in the phenotypic spectrum between them. One common classification of TD distinguishes affected infants based on the presence or absence of CS. In contrast, and as originally proposed by Langer et al. [1987: Am J Med Genet 3: 167-179], our data suggest that TD can be divided into at least two groups (TD1 and TD2) based on the presence of straight or curved femora. The variable presence of CS and severity of the radiologic and histologic findings in the other substitutions may be due to other genetic, environmental, or stochastic factors.

Antenatal sonographic diagnosis of thanatophoric dysplasia: a report of three cases and a review of the literature with special emphasis on the differential diagnosis

A series of three cases is reported in which the diagnosis of thanatophoric dysplasia was reached at routine mid-trimester scanning in a District General Hospital. All three patients underwent termination of pregnancy with the diagnosis of thanatophoric dysplasia confirmed by postmortem radiographic and histological examinations. A review of the current literature on thanatophoric dysplasia is given, with special emphasis on the differentiation of the main types of thanatophoric dysplasia from other skeletal abnormalities.

Holoprosencephaly-polydactyly ('pseudotrisomy 13') syndrome: a syndrome with features of hydrolethalus and Smith-Lemli-Opitz syndromes. A collaborative multicentre study

A syndrome of holoprosencephaly and postaxial polydactyly, associated with hydrocephalus, heart defect, adrenal hypoplasia, and other visceral malformations, has been observed in five unrelated children with normal chromosomes. Clinical overlap with lethal acrodysgenital dwarfism (Smith-Lemli-Opitz syndrome type II) and hydrolethalus syndrome is discussed. Recessive inheritance seems likely.

Lethal short-rib with median cleft and without polydactyly: a fourth case

A new case of Beemer short-rib lethal dwarfism is presented in a 27 weeks fetus with discussion of the radiological and clinical pecularities. Differential diagnosis with other short-rib-polydactyly syndromes is briefly developped.

Intrauterine diagnosis of short-limbed dwarfism

Ten short-limbed fetuses caused by skeletal dysplasia were diagnosed prenatally from September 1984 through July 1988. The final diagnosis was thanatophoric dwarfism in 7 cases and osteogenesis imperfecta congenita in 3 cases. The diagnosis was based on sonographic findings in all cases and postnatal radiography was performed in 3 cases for further confirmation. Sonographic examinations revealed markedly shortened limbs and other associated abnormalities, including abnormal skull appearance, pear-shaped chest with protuberant abdomen, polyhydramnios and hydrops in fetuses with thanatophoric dwarfism. Fetuses with osteogenesis imperfecta congenita were characterized by fractures of the long bones. These findings were helpful in making the specific diagnosis of short-limbed dwarfism. According to our experience, sonographic examination is effective in the prenatal diagnosis of short-limbed dwarfism.

First-trimester diagnosis of fetal abnormalities. A report of three cases

First-trimester sonography is used extensively for dating pregnancy and in conjunction with chorionic villus sampling. It is crucial to examine the fetus carefully, even at this early stage, since some fetal abnormalities are detectable in the first trimester. In three cases encephalocele, thanatophoric dwarf and cystic hygroma were diagnosed with sonography in the first trimester.

Achondrogenesis-hypochondrogenesis: the spectrum of chondrogenesis imperfecta. A radiological, ultrasonographic, and histopathologic study of 23 cases

In the classification of lethal osteochondrodysplasias, achondrogenesis and hypochondrogenesis have recently received special attention. We describe 23 cases representing the different subtypes. Within the classical type I (Parenti-Fraccaro) two distinct disorders can be recognized: type IA (Houston-Harris) and type IB (Fraccaro). The classical type II (Langer-Saldino) and hypochondrogenesis represent phenotypic variants of one disorder in which type II is the most severe form and hypochondrogenesis the mildest form, while transitional forms exist. It is likely that a basic defect in cellular function of the chondrocyte results in a deficient cartilage matrix and in disorganized enchondral ossification.

[Thanatophoric nanism: a case of early ultrasonic diagnosis]

The diagnosis of a thanatophorous nanism is evoked in the presence of an abnormality of the size of the long bones. This study records the symptoms which, on sonograms, permit to recognize this fatal form of nanism among other forms of metaphysis chondrodysplasia, in order to establish a diagnosis before deciding to interrupt the pregnancy.

The importance of early prenatal diagnosis of thanatophoric dysplasia with respect to obstetric management

A case is described in which prenatal diagnosis of thanatophoric dysplasia was made in the second trimester of pregnancy by ultrasonography and radiography. Early diagnosis allowed elective abortion to be carried out, thus avoiding possible complications later in the pregnancy.

[Prenatal diagnosis of thanatophoric dwarfism with cloverleaf skull]

Thanatophoric dwarfism is a rare condition occurring in 1 in 100,000 births. To date, only 2 cases have been reported on in which this condition was diagnosed prenatally before the 24th week of pregnancy post menstruationem. The majority of cases reported so far were born by cesarean section. This condition can be diagnosed early by measurement of the fetal diaphyseal bones and accompanying specific diagnostic measures to establish the possible presence of malformations. The pregnancy can then be terminated if need be, and unnecessary interventions thus avoided.

Thanatophoric dysplasia: fetal manifestations and prenatal diagnosis

This paper describes two fetuses with thanatophoric dysplasia (TD) diagnosed in utero by ultrasonography. The fetuses were found to have severely short (less than 3rd centile), mildly bowed bones in one of them at 20 weeks and straight bones in the other at 34 weeks; bell-shaped chest; abnormal ribs (broadened and flattened at their ends); severe lung hypoplasia; hypoplastic, round-shaped vertebral bodies with hypoplastic arches; abnormally small pelvic bones, phalanges, metacarpals, and metatarsals. There was also an incipient "cloverleaf" skull deformity produced by fused posterior sagittal and lambdoidal sutures in the 20-week fetus and a definitive cloverleaf skull with communicating hydrocephaly in the 34-week fetus. The autopsies did not show any other abnormality. By xeroradiography after delivery, marked abnormalities of the endochondral and perichondral bone structures could be demonstrated in the 20-week fetus but not in the 34-week fetus. They appear to constitute two different conditions. These cases are good examples of the possibilities brought by ultrasound to the analysis of the fetal phenotype in utero.

Lethal neonatal chondrodysplasias in the West of Scotland 1970-1983 with a description of a thanatophoric, dysplasialike, autosomal recessive disorder, Glasgow variant

Complete ascertainment of lethal neonatal short-limb chondrodysplasias was attempted in the West of Scotland for the period 1970-1983. Forty-three cases were identified, representing a minimum incidence of 1 in 8,900. The differential diagnosis included 11 well-delineated skeletal dysplasias, one case of warfarin embryopathy, and one apparently new condition with presumed autosomal recessive inheritance that has radiographic similarities to those of thanatophoric dysplasia (TD). In this series TD had an incidence of 1 in 42,221, which is consistent with new dominant mutation at a rate of 11.8 +/- 4.1 X 10(-6) mutations per gene per generation. Ultrasonic measurement of fetal long bone length was performed in eight subsequent pregnancies at risk. Five unaffected fetuses were predicted correctly and three affected fetuses were detected during the second trimester (one with rhizomelic chondrodysplasia punctata-second trimester prenatal diagnosis not previously reported; one with achondrogenesis type II; and one with the new lethal condition).

Dyssegmental dysplasia (report of two cases with a review of the literature)

Two cases of dyssegmental dysplasia, a rare lethal skeletal dysplasia in the newborn, are reported. Two different forms of dyssegmental dysplasia can be distinguished--the lethal Silverman type and the less severe Rolland-Desbuquois type. In this report, both cases are of the Silverman type. Histopathology of chondro-osseous tissue confirms the similarity in pathologic findings to Kniest dysplasia.

Prenatal diagnosis of Jeune syndrome

We describe two sibs affected with Jeune syndrome. The first was diagnosed after birth and the second was diagnosed prenatally using ultrasonography. The detected abnormalities were confirmed by X-ray and autopsy following pregnancy termination. This observation indicates the possibility of prenatal diagnosis of the condition.

Ultrasonic demonstration of fetal skeletal dysplasia. Case reports

Reports on prenatal diagnosis in cases of skeletal dysplasia have mostly been in high-risk mothers with a suspect genetic background where the fetal lesion could probably be predetermined. We deal with routine ultrasonographic appraisal of the fetal skeleton when dysplasia is not initially suspected, and relate our experience of the lethal forms of this condition. During the 4-year period 1981-1984, 6 cases of skeletal dysplasia, including thanatophoric dysplasia, achondrogenesis, the Ellis-van Creveld syndrome (chondro-ectodermal dysplasia) and osteogenesis imperfecta, were detected; the ultrasonographic findings are discussed.