Molecular Analysis of the ERGIC-53 Gene in 35 Families With Combined Factor V-Factor VIII Deficiency

Abstract

Combined factor V-factor VIII deficiency (F5F8D) is a rare, autosomal recessive coagulation disorder in which the levels of both coagulation factors V and VIII are diminished. The F5F8D locus was previously mapped to a 1-cM interval on chromosome 18q21. Mutations in a candidate gene in this region, ERGIC-53, were recently found to be associated with the coagulation defect in nine Jewish families. We performed single-strand conformation and sequence analysis of the ERGIC-53 gene in 35 F5F8D families of different ethnic origins. We identified 13 distinct mutations accounting for 52 of 70 mutant alleles. These were 3 splice site mutations, 6 insertions and deletions resulting in translational frameshifts, 3 nonsense codons, and elimination of the translation initiation codon. These mutations are predicted to result in synthesis of either a truncated protein product or no protein at all. This study revealed that F5F8D shows extensive allelic heterogeneity and all ERGIC-53 mutations resulting in F5F8D are “null.” Approximately 26% of the mutations have not been identified, suggesting that lesions in regulatory elements or severe abnormalities within the introns may be responsible for the disease in these individuals. In two such families, ERGIC-53 protein was detectable at normal levels in patients’ lymphocytes, raising the further possibility of defects at other genetic loci.

Combined factor V and factor VIII deficiency in a Thai patient: a case report of genotype and phenotype characteristics

“…The other mutation is 1366C fi T, a nonsense mutation in exon 11 that causes a change from a CGA to a TGA (R456X). The same mutation had been reported previously [15]. Her father is heterozygote for the 823-1G fi C mutation and her mother is heterozygote for the 1366C fi T mutation.…”

“…This report describes a native Thai family with no consanguinity. Previous studies have demonstrated that LMAN1 is required for efficient secretion of factor VIII and factor V and that this is mediated by oligosaccharide structures within their respective B domains [11][12][13][14][15][16][17]. In the absence of LMAN1, MCFD2 is also not retained with the ER or intermediate compartment.…”

“…Shortly after that, the recombinant interval at chromosome 18q21 was matched to the gene LMAN1 (previously identified as ERGIC-53), a protein of the endoplasmic reticulum (ER)-Golgi intermediate compartment with previously unknown function [12][13][14]. At present, LMAN1 mutations are identified in 74% of the patients [15,16]. Until 2003, Zhang et al [17] described mutations in a second gene, called multiple combined factor deficiency 2 (MCFD2) on chromosome 2, which forms the complex to the ERGIC through a direct, calcium-dependent interaction with LMAN1.…”

Sequential steps and checkpoints in the early exocytic compartment during secretory IgM biogenesis

“…ERGIC-53 shuttles between the ER and the Golgi because it can bind both COPI and COPII through its KKFF cytosolic terminus (Schindler et al, 1993;Vollenweider et al, 1998). Mutations in ERGIC-53 (also known as LMAN1) are responsible for most cases of combined deficiency of coagulation factor V and VIII (F5F8D), a recessive bleeding disorder caused by decreased blood levels of both clotting factors (Nichols et al, 1998;Neerman-Arbez et al, 1999). This implies a role for ERGIC-53 in factors V and VIII ER-Golgi transport (Vollenweider et al, 1998).…”

Cell Biology of Membrane Trafficking in Human Disease

“…Some F5F8D patients are deficient in the ERGIC-localized ERGIC-53 (LMAN1) protein and display defective secretion of the factor V and VIII clotting factors. ERGIC-53 is a mannosebinding lectin that acts as a ''cargo receptor'' and recycles between the ER and ERGIC (Neerman-Arbez et al, 1999;. However, 30% of F5F8D patients show normal levels of ERGIC-53/LMAN1, but are deficient in an associated protein, MCFD2, another ERGIC resident that interacts with ERGIC-53/LMAN1 in a calcium-dependent manner .…”