Brain alteration in a Nude/SCID fetus carrying FOXN1 homozygous mutation.

A critical role of the FOX transcription factors in the development of different tissues has been shown. Among these genes, FOXN1 encodes a protein whose alteration is responsible for the Nude/SCID phenotype. Recently, our group reported on a human Nude/SCID fetus, which also had severe neural tube defects, namely anencephaly and spina bifida. This led to hypothesize that FOXN1 could have a role in the early stages of central nervous system development. Here we report on a second fetus that carried the R255X homozygous mutation in FOXN1 that has been examined for the presence of CNS developmental anomalies. At 16 postmenstrual weeks of gestation, the abdominal ultrasonography of the Nude/SCID fetus revealed a morphologically normal brain, but with absence of cavum septi pellucidi (CSP). Moreover, after confirmation of the diagnosis of severe Nude/SCID, the fetus was further examined postmortem and a first gross examination revealed an enlargement of the interhemispheric fissure. Subsequently, a magnetic resonance imaging failed to identify the corpus callosum in any section. In conclusion, our observations did not reveal any gross abnormalities in the CNS anatomy of the Nude/SCID fetus, but alteration of the corpus callosum, suggesting that FOXN1 alterations could play a role as a cofactor in CNS development in a similar fashion to other FOX family members.