Prenatal diagnosis of campomelic dysplasia

Case report: Cystic hygroma accompanied with campomelic dysplasia in the first trimester caused by haploinsufficiency with SOX9 deletion

Introduction: Campomelic dysplasia (CD) is a rare autosomal dominant skeletal malformation syndrome characterized by shortness and bowing of the lower extremities with or without XY sex reversal. Diagnosis using ultrasonography is most often made in the latter half of pregnancy. Intragenic heterozygous mutations in SOX9 are responsible for most cases of CD. CD caused by SOX9 deletion is a rare condition.

Case presentation: We present a single case report of an individual with cystic hygroma accompanied by CD, which was detected by ultrasound in the first trimester. Chromosomal microarray analysis (CMA) was performed to determine copy number variants, whereas whole exome sequencing (WES) was performed to elucidate single-nucleotide variants. Chorionic villus sampling was performed to enable such analyses. Ultimately, CMA detected a 606 kb deletion in the 17q24.3 region with only one protein-coding gene (SOX9). However, no mutation in the SOX9 protein-coding sequence was detected by WES.

Conclusion: When cystic hygroma is detected, prenatal diagnoses for skeletal dysplasia by ultrasound are likely to be confirmed in the first trimester. We propose a comprehensive prenatal diagnostic strategy that combines CMA and WES to diagnose fetuses with cystic hygroma accompanied by skeletal dysplasia.

Case report: A de novo Non-sense SOX9 mutation (p.Q417*) located in transactivation domain is Responsible for Campomelic Dysplasia

BACKGROUND

Campomelic dysplasia (CD) is an autosomal dominant skeletal dysplasia syndrome characterized by shortness and bowing of lower extremities, and often accompanied by XY sex reversal. Heterozygous pathogenic variants of SOX9 or rearrangement involving the long arm of chromosome 17 are the causes of disease. However, evidence for pathogenesis of SOX9 haploinsufficiency is insufficient.

METHODS

We enrolled a Chinese family where the fetus was diagnosed with CD. The affected fetus was selected for whole-exome sequencing to identify the pathogenic mutations in this family.

RESULTS

After data filtering, a novel non-sense SOX9 variant (NM_000346.3; c.1249C > T; p.Q417*) was identified as the pathogenic lesion in the fetus. Further co-segregation analysis using Sanger sequencing confirmed that this novel SOX9 mutation (c.1249C > T; p.Q417*) was a de novo mutation in the affected fetus. This terminated codon mutation identified by bioinformatics was located at an evolutionarily conserved site of SOX9. The bioinformatics-based analysis predicted this variant was pathogenic and affected SOX9 transactivation activity.

CONCLUSION

CD is a rare condition, which connected with SOX9 tightly. We identified a novel heterozygous SOX9 variant (p.Q417*) in a Chinese CD family. Our study supports the putative reduced transactivation of SOX9 variants in the pathogenicity of CD.

Integrative mid-trimester anomaly (IMTA) chart: a novel sonographic approach for syndromatic challenges (pilot study)

OBJECTIVE

To validate the use of the integrative mid-trimester anomaly (IMTA) chart, a novel chart that aims to increase sonographers' ability to diagnose fetal syndromes and complex anomalies.

METHODS

This study was conducted between September 2014 and January 2015. Pregnant women who attended our hospital for fetal medicine consultation during the second trimester were recruited. The diagnosis was assigned by a qualified consultant. The research coordinator randomized women between two groups (each consisted of two sonographers with comparable experience) and each was then examined twice (once with and once without the chart). Supposed diagnosis, patient and sonographer satisfactions were reported.

RESULTS

Twenty five women were recruited. Their average age was 26.48 ± 4.49 years and gestational age at examination was 24.39 ± 6.39. There were 17 (68%) fetuses that had multiple anomalies. The duration of examination was comparable. However, patient and sonographer satisfactions were higher when the same women were examined with the chart (p < 0.0001). The accuracy of diagnosis was also significantly higher (p = 0.03).

CONCLUSION

The IMTA chart seems to be a useful tool for novice sonographers that could increase their diagnostic accuracy and improve their patient and their own satisfaction.