Perinatal Diagnostic Approach to Fetal Skeletal Dysplasias: Six Years Experience of a Tertiary Center

Fetal autopsy for the diagnosis of skeletal dysplasia and comparison with prenatal ultrasound findings over a 16-year period

OBJECTIVES

To evaluate the relationship between prenatal ultrasonography (USG) and fetal autopsy findings.

METHODS

Among 453 pregnancy terminations performed because of fetal anomalies on prenatal USG, 54 with skeletal dysplasia on fetal autopsy were included in this retrospective study.

RESULTS

The most common diagnoses among the 54 fetal autopsies were osteogenesis imperfecta (n=12), dysostosis (n=10), achondroplasia (n=9), arthrogryposis (n=6), and thanatophoric dysplasia (n=6). The prenatal USG and fetal autopsy findings showed complete agreement in 35 cases (64.8%), partial agreement in nine cases (16.6%), and disagreement in 10 cases (18.5%).

CONCLUSIONS

Fetal autopsy via perinatal pathology is essential for precise identification of the type of skeletal dysplasia; it should be routinely performed to confirm the diagnosis of prenatally detected fetal anomalies. Autopsy is vital for accurate prenatal diagnosis and the 'gold standard' technique for the identification of clinically important abnormalities.

Achondroplasia in Latin America: practical recommendations for the multidisciplinary care of pediatric patients

Background

Achondroplasia is the most common bone dysplasia associated with disproportionate short stature, and other comorbidities, such as foramen magnum stenosis, thoracolumbar kyphosis, lumbar hyperlordosis, genu varum and spinal compression. Additionally, patients affected with this condition have higher frequency of sleep disorders, ear infections, hearing loss and slowed development milestones. Considering these clinical features, we aimed to summarize the regional experts’ recommendations for the multidisciplinary management of patients with achondroplasia in Latin America, a vast geographic territory with multicultural characteristics and with socio-economical differences of developing countries.

Methods

Latin American experts (from Argentina, Brazil, Chile and Colombia) particiáted of an Advisory Board meeting (October 2019), and had a structured discussion how patients with achondroplasia are followed in their healthcare centers and punctuated gaps and opportunities for regional improvement in the management of achondroplasia.

Results

Practical recommendations have been established for genetic counselling, prenatal diagnosis and planning of delivery in patients with achondroplasia. An outline of strategies was added as follow-up guidelines to specialists according to patient developmental phases, amongst them neurologic, orthopedic, otorhinolaryngologic, nutritional and anthropometric aspects, and related to development milestones. Additionally, the role of physical therapy, physical activity, phonoaudiology and other care related to the quality of life of patients and their families were discussed. Preoperative recommendations to patients with achondroplasia were also included.

Conclusions

This study summarized the main expert recommendations for the health care professionals management of achondroplasia in Latin America, reinforcing that achondroplasia-associated comorbidities are not limited to orthopedic concerns.

MR Virtual Endoscopy of the Fetal Limb Anomalies Using Three-Dimensional Fast Imaging Employing Steady-State Acquisition Sequence

OBJECTIVE

To retrospectively investigate the feasibility of magnetic resonance virtual endoscopy (MRVE) to visualize the normal limbs and limb deformities Methods: MR sequences included two-dimensional (2D) single fast spin-echo sequence and 2D and 3D steady-state procession fast imaging sequences. MRVE reconstruction was retrospectively performed by 2 radiologists in 32 fetuses in 30 pregnant women. The correlation between the radiologists for the virtual endoscopy threshold of MRVE was determined. Image quality and limb segment visibility were independently rated. Area under the receiver operating characteristics curve (AUC) of 2D MRI and MRVE was calculated.

RESULTS

The mean virtual endoscopy threshold required for the visualization of the limb was 991.93 ± 12.13 and 991.83 ± 12.26 for 2 radiologists, respectively. The correlation between the radiologists for virtual endoscopy threshold was excellent (r = 0.933). The weighted kappa statistic was 0.96 for the evaluation of image quality of limb segments, indicating excellent interobserver agreement. Compared to that of 2D MRI alone, a higher AUC of 2D MRI with MRVE was achieved in detection of both upper and lower limb deformities (0.91 vs. 0.69 and 0.83 vs. 0.71, respectively).

CONCLUSION

MRVE may display normal and abnormal fetal limb orientation and structures from multiple perspectives and provide incremental information for obstetrics.

Frequency of skeletal anomalies in fetal and neonatal autopsies

Introduction: Skeletal anomalies are a heterogeneous group of disorders including changes in bone shape, size, and density that cause abnormalities of the extremities, trunk, and head. They rank second in Europe in the frequency of all congenital anomalies. The most common skeletal anomalies include head, face and limb anomalies. Aim: The aim of this study was to determine the frequency of skeletal anomalies and their association with anomalies of internal organs, as well as to show the age of the mother and the gestational week of the fetus with established skeletal anomalies. Material and methods: All fetal and neonatal autopsies in the period from January 1, 2018 to December 31, 2020 at the Institute of Pathology "Djordje Joannovic" of the Faculty of Medicine University of Belgrade were analyzed. In the mentioned period, 580 fetal and neonatal autopsies were performed. Clinical data were obtained from the Gynecology and Obstetrics Clinic "Narodni Front" on the basis of completed requests for clinical autopsy. Descriptive statistics methods were used (data are presented as absolute numbers and percentage frequencies). Results: The most common skeletal anomalies are divided into seven groups: spina bifida (20; 33.34%), limb anomalies (16; 26.67%), head and face bone anomalies (15; 25%), joint anomalies (2; 3.33%), achondroplasia (3; 5%), osteogenesis imperfecta (2; 3.33%) and other anomalies (2; 3.33%). The most common associated anomalies were central nervous system (CNS) abnormalities, followed by heart and kidney abnormalities. The youngest mother was 15 years old, and the oldest was 47 years old. The mean age of the mothers was 30 years. Conclusion: In our study, the most common anomaly was spina bifida, while limb anomalies and craniofacial anomalies are next in frequency. Skeletal anomalies were often associated with anomalies of the heart, kidneys, and CNS. They were mostly diagnosed between the 22nd and 27th gestational week. Our results showed that skeletal anomalies are more common in fetuses or neonates of mothers older than 30 years.

Clinical value of genetic analysis in prenatal diagnosis of short femur

Background

Fetal femur length (FL) is an important biometric index in prenatal screening. The etiology of short femur is diverse, with some pathogenic causes leading to adverse outcomes. To improve the accuracy and practicability of diagnosis, we investigated the value of genetic analysis in prenatal diagnosis of short femur.

Methods

We examined chromosomal microarray analysis (CMA) (64 fetuses) and karyotyping (59 fetuses) data retrospectively for short femur without fetal growth restriction (FGR). Genetic testing was conducted for 15 fetuses.

Results

Karyotyping and CMA detected chromosomal aberrations at rates of 13.6% and 27.2%, respectively. Among fetuses with other abnormalities, detection rates were 21.0% higher with CMA than karyotyping. CMA identified chromosomal abnormalities in 36.4% of cases with a FL 2–4 standard deviations (SDs) below the gestational age (GA) mean. Abnormality detection by CMA reached 38.5% in the second trimester. Duplication of 12p, 16p13.1 deletion, and uniparental disomy 16 were identified by CMA in three cases of short femur. Gene sequencing detected clinically notable mutations in 12/15 fetuses, among which 9/12 fetuses had FLs >4 SDs below the GA mean.

Conclusions

CMA yielded a higher detection value than karyotyping in fetuses with other abnormalities or a FL 2–4 SDs below the GA mean during the second trimester. Gene sequencing should be performed when FL is >4 SDs below the mean.

Prenatal diagnosis of Desbuquois dysplasia type 1 by whole exome sequencing before the occurrence of specific ultrasound signs

Desbuquois dysplasia is a very severe and sometimes lethal form of osteochondrodysplasia characterized by prenatal onset of severe micromelic short stature, joint laxity with multiple joint dislocations, specific radiographic features, and facial dysmorphism. Here, we report a case for which whole exome sequencing allowed early prenatal diagnosis of Desbuquois dysplasia before the detection of characteristic ultrasound signs of the disease.

Prenatal diagnosis of fetal skeletal dysplasia using targeted next-generation sequencing: an analysis of 30 cases

Background

This study aims to provide genetic diagnoses for 30 cases of fetal skeletal dysplasia, and a molecular basis for the future prenatal diagnosis of fetal skeletal dysplasia.

Methods

A total of 30 cases of fetal skeletal dysplasia detected with ultrasound between January 2014 and June 2017 were analyzed. Among these fetuses, 15 fetuses had local skeletal malformations, while 15 fetuses had short limb malformations. Samples of fetal umbilical cord blood, amniotic fluid, and/or aborted tissue were collected from all cases. Karyotyping, whole genome sequencing, and targeted next-generation sequencing of skeletal disease-related pathogenic genes were performed, as needed. Blood samples were taken from the parents for verification using Sanger sequencing.

Results

Among the 30 cases of fetal skeletal dysplasia, two cases were diagnosed with trisomy 18. However, none of these cases were identified with any microdeletions or microreplications associated with skeletal dysplasia. Among the 28 chromosomally normal cases with fetal skeletal dysplasia, 21 cases were detected with mutations in genes related to skeletal diseases. Furthermore, collagen gene mutations were detected in six fetuses with short limb malformations, while heterozygous disease-causing mutations in the fibroblast growth factor receptor 3 (FGFR3) gene were detected in seven fetuses. The remaining fetuses carried mutations in other various genes, including tumor protein p63 (TP63), cholestenol delta-isomerase (EBP), cholinergic receptor nicotinic gamma subunit (CHRNG), filamin B (FLNB), and SRY-box 9 (SOX9). Three compound heterozygous mutations in CHRNG, COL11A2 and SOX9 were carried by phenotypically healthy parents.

Conclusion

Targeted next-generation sequencing can significantly improve the prenatal diagnoses of fetal skeletal dysplasia, providing parents with more precision medicine, and improved genetic counseling.

Follow-Up Study on Fetal CT Radiation Dose in Japan: Validating the Decrease in Radiation Dose

OBJECTIVE

In 2011, we collected data on fetal CT radiation dose to determine the diagnostic reference level (DRL); however, continuous evaluation of the DRL is necessary. The hypothesis of this study is that the fetal CT radiation dose has decreased, and we predict a widespread use of iterative reconstruction (IR). We also predict that the national decrease in exposure is because of the DRL reported as a result of the previous national study.

MATERIALS AND METHODS

Various testing protocols from each site were summarized as part of the study results. The minimum, one-fourth (25th percentile), median, three-fourths (75th percentile), and maximum values were obtained for volume CT dose index (CTDI_vol), dose-length product (DLP), and scan length of 120 fetal CT examinations. The trends for IR usage and tube voltage were also investigated.

RESULTS

Compared to the results of the 2011 study (n = 119), the minimum, 25th percentile, median, and 75th percentile values for CTDI_vol and DLP have decreased for the tabulated results in 2015 (n = 120). The 75th percentile value for CTDI_vol was 4.9 mGy, which is 43% of the previous value. IR was used in 70% of the sites. The radiation dose was significantly lower among groups that used IR.

CONCLUSION

Four years passed between our initial survey on DRL and the present follow-up survey, and it appears that the previous report sufficiently fulfilled its objective and role in contributing to the decrease in DRL observed in this follow-up study.