Co-Occurence of Reciprocal Translocation and COL2A1 Mutation in a Fetus with Severe Skeletal Dysplasia: Implications for Genetic Counseling

Familial Aggregation of a Novel Missense Variant of COL2A1 Gene Associated with Short Extremities: Case Report and Review of the Literature

We present two cases of family members (first cousins) with short extremities caused by a novel variant of COL2A1 gene (NM_001844.5). Case 1 description: A 29-year-old woman presented in her first pregnancy for a second trimester anomaly scan at 23 weeks of gestation. Fetal long bones were measured below the third centile for gestational age. Follow-up scans revealed fetal long bone growth deceleration. Initial genetic work-up was negative and the rest of the maternal follow-up was unremarkable. A male baby weighing 3180 g was delivered at 39 weeks and 4 days of gestation. Case 2 description: A 33-year-old pregnant woman presented for a routine second trimester anomaly scan at 20 weeks and 4 days of gestation. All fetal measurements were appropriate for the gestational age. The routine growth scan performed at 32 weeks showed fetal long bone measurements below the third centile for gestational age, while the follow-up growth scan at 36 weeks and 4 days of gestation revealed consistent, below the third centile, fetal long bone growth. Given that the fetuses of these two cases were related (first cousins), whole exome sequencing (WES) was performed on Case 2. WES revealed a novel heterozygous missense variant c.1132G>A (p. Gly378Ser) of COL2A1 gene (NM_001844.5). Subsequently, targeted genetic sequencing for the variant was performed on Case 1 and the same novel variant was found. Targeted sequencing revealed the same variant in the mother of Case 1 and the father of Case 2 (siblings). A female baby weighing 3200 g was delivered at 40 weeks and 4 days of gestation.

A system-based approach to the genetic etiologies of non-immune hydrops fetalis

A wide spectrum of genetic causes may lead to nonimmune hydrops fetalis (NIHF), and a thorough phenotypic and genetic evaluation are essential to determine the underlying etiology, optimally manage these pregnancies, and inform discussions about anticipated prognosis. In this review, we outline the known genetic etiologies of NIHF by fetal organ system affected, and provide a systematic approach to the evaluation of NIHF. Some of the underlying genetic disorders are associated with characteristic phenotypic features that may be seen on prenatal ultrasound, such as hepatomegaly with lysosomal storage disorders, hyperechoic kidneys with congenital nephrosis, or pulmonary valve stenosis with RASopathies. However, this is not always the case, and the approach to evaluation must include prenatal ultrasound findings as well as genetic testing and many other factors. Genetic testing that has been utilized for NIHF ranges from standard chromosomal microarray or karyotype to gene panels and broad approaches such as whole exome sequencing. Family and obstetric history, as well as pathology examination, can yield additional clues that are helpful in establishing a diagnosis. A systematic approach to evaluation can guide a more targeted approach to genetic evaluation, diagnosis, and management of NIHF.

Best practice guidelines regarding prenatal evaluation and delivery of patients with skeletal dysplasia

BACKGROUND

Skeletal dysplasia comprises a heterogeneous and collectively common group of inherited disorders of development, growth, and maintenance of the human skeleton. There is potential for increased perinatal morbidity and mortality in pregnant women who themselves have skeletal dysplasia, and for affected fetuses where skeletal dysplasia is suspected in utero.

OBJECTIVE

We sought to establish guidelines for perinatal health care professionals who should be aware of these risks, to optimize maternal and child health pregnancy outcomes through best prenatal and delivery management practices.

STUDY DESIGN

A panel of 13 multidisciplinary international experts participated in a Delphi process, which comprised consideration of thorough literature review and a list of 54 possible care recommendations subject to 2 rounds of anonymous voting and a face-to-face meeting. Those recommendations with >80% agreement were considered as consensual.

RESULTS

During the first round, consensus was reached to support 30 out of the 54 statements. After the panel discussion, the group reached consensus on 40 statements. These statements include guidelines for the evaluation and treatment of pregnant women with skeletal dysplasia and for the unborn child with or suspected to have skeletal dysplasia.

CONCLUSION

Consensus-based best practice guidelines are provided as a minimum of standard care to minimize associated health risks, and improve clinical outcomes for patients with skeletal dysplasia.