Prenatal identification of a pathogenic maternal FGFR1 variant in two consecutive pregnancies with fetal forebrain malformations.

OBJECTIVE

Holoprosencephaly (HPE) is the most common aberration of forebrain development, and it leads to a wide spectrum of developmental and craniofacial anomalies. HPE etiology is highly heterogeneous and includes both chromosomal abnormalities and single-gene defects.

METHODS

Here, we report an FGFR1 heterozygous variant detected by prenatal exome sequencing and inherited from the asymptomatic mother, in association with recurrent neurological abnormalities in the HPE spectrum in two consecutive pregnancies.

RESULTS

Individuals with germline pathogenic variants in FGFR1 (MIM: 136350) show extensive phenotypic variability, which ranges from asymptomatic carriers to hypogonadotropic hypogonadism, arhinencephaly, Kallmann's syndrome with associated features such as cleft lip and palate, skeletal anomalies, isolated HPE, and Hartsfield syndrome.

CONCLUSION

The presented case supports the role of exome sequencing in prenatal diagnosis when fetal midline structural anomalies are suggestive of a genetic etiology, as early as the first trimester of gestation. The profound heterogeneity of FGFR1 allelic disorders needs to be considered when planning prenatal screening even in asymptomatic carriers.