Deficiency of FRAS1-related extracellular matrix 1 (FREM1) causes congenital diaphragmatic hernia in humans and mice

Abstract

Congenital diaphragmatic hernia (CDH) is a common life-threatening birth defect. Recessive mutations in the FRAS1-related extracellular matrix 1 (FREM1) gene have been shown to cause bifid nose with or without anorectal and renal anomalies (BNAR) syndrome and Manitoba oculotrichoanal (MOTA) syndrome, but have not been previously implicated in the development of CDH. We have identified a female child with an isolated left-sided posterolateral CDH covered by a membranous sac who had no features suggestive of BNAR or MOTA syndromes. This child carries a maternally-inherited ~86 kb FREM1 deletion that affects the expression of FREM1's full-length transcripts and a paternally-inherited splice site mutation that causes activation of a cryptic splice site, leading to a shift in the reading frame and premature termination of all forms of the FREM1 protein. This suggests that recessive FREM1 mutations can cause isolated CDH in humans. Further evidence for the role of FREM1 in the development of CDH comes from an N-ethyl-N-nitrosourea -derived mouse strain, eyes2, which has a homozygous truncating mutation in Frem1. Frem1(eyes2) mice have eye defects, renal agenesis and develop retrosternal diaphragmatic hernias which are covered by a membranous sac. We confirmed that Frem1 is expressed in the anterior portion of the developing diaphragm and found that Frem1(eyes2) embryos had decreased levels of cell proliferation in their developing diaphragms when compared to wild-type embryos. We conclude that FREM1 plays a critical role in the development of the diaphragm and that FREM1 deficiency can cause CDH in both humans and mice.

Congenital heart defects and left ventricular non-compaction in males with loss-of-function variants inNONO

“…Quantitative RT-PCR analyses were performed as previously described using NONO primers 5′-ACCACCGCCAATACCT-3′ and 5′-CGCCTGCCTTTCCATATTTC-3′, with glyceraldehyde-3-phosphate dehydrogenase ( GAPDH ) primers 5′-CCCACTCCTCCACCTTTGACGCT-3′ and 5′-TTCAAGGGGTCTACATGGCAACT-5′ being used for control amplification 18 19. Data were analysed using the delta–delta C t method 20…”

Genetic causes of congenital diaphragmatic hernia

“…There is a single case of isolated CDH with an 86 kb deletion at 9p22.3 encompassing FREM1 and a splice mutation in the other copy of FREM1 [65]. This child had no features of the FREM1-related syndromes, which include bifid nose with anorectal and renal anomalies.…”

FBN1 contributing to familial congenital diaphragmatic hernia

“…Although sometimes difficult to identify, these genetic factors may have a significant influence on the penetrance of other CDH‐related mutations in individuals, families and clans [Lupski et al, ]. This has been clearly demonstrated in mouse models in which the penetrance of CDH associated with specific mutations varies significantly in different genetic backgrounds [Wat et al, ; Beck et al, 20013a; Beck et al, ].…”