Skeletal dysplasia with bowing long bones: Proposed flowchart for prenatal diagnosis with case demonstration

Prenatal ultrasound findings and prenatal diagnosis of fetal skeletal dysplasia

OBJECTIVE

To analyze the value of prenatal ultrasound and molecular testing in diagnosing fetal skeletal dysplasia (SD).

METHODS

Clinical data, prenatal ultrasound data, and molecular results of pregnant women with fetal SD were collected in the ultrasound department of our clinic from May 2019 to December 2021.

RESULTS

A total of 40 pregnant women with fetal SD were included, with 82.5% exhibiting short limb deformity, followed by 25.0% with central nervous system malformations, 17.50% with facial malformations, 15% with cardiac malformations, and 12.5% with urinary system malformations. The genetic testing positive rate was 70.0% (28/40), with 92.8% (26/28) being single-gene disorders due to mutations in FGFR3, COL1A1, COL1A2, EVC2, FLNB, LBR, and TRPV4 genes. The most common SD subtypes were osteogenesis imperfecta (OI), thanatophoric dysplasia (TD), and achondroplasia (ACH). The gestational age (GA) at initial diagnosis for TD, OI, and ACH was 16.6, 20.9, and 28.3 weeks, respectively (p < 0.05), with no significant difference in femoral shortening between the three groups (p > 0.05). Of the OI cases, 5 out of 12 had a family history.

CONCLUSION

Short limb deformity is the most prevalent phenotype of SD. When fetal SD is suspected, detailed ultrasound screening should be conducted, combined with GA at initial diagnosis, family history, and molecular evidence, to facilitate more accurate diagnosis and enhance prenatal counseling and perinatal management.

Severe skeletal dysplasia caused by a novel FLNB gene mutation

A late adolescent primigravida was found to have a fetus with a cystic hygroma and significant shortening of the limbs on first-trimester ultrasound. She underwent chorionic villus sampling with normal microarray result. In the early second trimester, the fetus was found to have the absence of all four limbs and a thorough skeletal dysplasia workup was pursued, identifying a variant in the FLNB gene (c.62C>G). The patient underwent termination of pregnancy. The care of this patient was expedited by first-trimester sonographic evidence of limb abnormalities enabling timely clinical management.

NOTCH2 related disorders: Description and review of the fetal presentation

Signs of skeletal dysplasias are relatively common in fetuses with abnormal ultrasound (US) findings. The diversity of congenital skeletal disorders, the possibility of late-onset severe phenotypes and overlapping syndromes can be a challenge in the way of diagnosis, even if prenatal high-throuput sequencing allows for a better diagnosis, prognosis and genetic counseling. Hajdu-Cheney spectrum pathologies are rarely described in prenatal, and the signs associated remain poorly known, and do not include specific postnatal signs as acro-osteolysis and premature osteoporosis. We hereby report a couple for whom a medical termination of pregnancy was performed because a severe polymalformative syndrome associating severely short limbs with bowed long bones, severe cardiopathy, hyperechogenic kidneys and dysmorphism. After fetopathological and radiological examinations, Exome Sequencing (ES) was performed and revealed a de novo truncating mutation in the last exon of NOTCH2, responsible for Hajdu-Cheney or Serpentine Fibula Polycystic Kidney syndromes.

Whole exome sequencing, clinical exome or targeted gene panels: what to choose for suspected lethal skeletal dysplasia (short rib thoracic dysplasia type IV)

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.