Molecular characterization of five Italian families with inherited severe factor XIII deficiency

Abstract

Factor XIII (FXIII) deficiency is a very rare (1:2 000 000) severe autosomal recessive bleeding disorder, mostly due to mutations in the coagulation FXIII A-subunit gene. We have studied the molecular basis of FXIII deficiency in five unrelated Italian families. The coding region, intron-exon boundaries and 5'- and 3'-untranslated regions of the FXIII gene encoding the A subunit were amplified and directly sequenced. Candidate mutations were identified in all the patients. Three novel mutations occurred in three patients. These include a novel homozygous deletion of two base pairs (bp) in exon 14 (c.2002-2003 DelCT). This deletion causes a frameshift from Leu667 and the formation of a stop codon at amino acid position 681. The second patient presents a novel homozygous (c.2126 G>A) transition in exon 15, predicting a Ser708Asn in Barrel 2 domain. The third patient is compound heterozygote for two missense mutations, a previously reported Arg260His substitution, and a novel transition in exon 4 (c.560 C>T) predicting a Pro186Leu in the core domain. The remaining two patients have two previously reported mutations: a 4-bp homozygous deletion in exon 11 (c.1392-1395 Del AATT), previously reported to occur in the Vicenza Area, and a homozygous nonsense mutation in exon 8 (c.979 C>T) predicting an Arg326X in the core domain. The novel mutations occurred at amino acid residues highly conserved among different species (pig, monkey, mouse and dog) and were not detected in 110 normal alleles. Structural analysis shows that Pro186Leu mutation leads to the replacement of the rigid proline pyrrolidine ring by the larger and more flexible leucine side chain and Ser708Asn may probably disrupt the hydrogen bond with Ala291.

Pathogenicity analysis of variations and prenatal diagnosis in a hereditary coagulation factor XIII deficiency family

“…In our study, we detected Pro564 Leu, Val650Ile and Glu651Gln and their allele frequencies all exceeded 1% among the population (21.6, 6.759, 20.87%, respectively) according to Exome Aggregation Consortium; so we classified them as polymorphisms which are likely benign. The c.1226G > A (p. Arg408Gln) in exon 10 of the F13A gene had been detected in England, Tunis and India [23][24][25][26]. For the first time, we found c.1226G > C (p. Arg408Pro).…”

Further evidence of heterogeneity of gene defects in Italian families with factor XIII deficiency

“…We recently reported the molecular characterization of five Italian families with FXIIIA deficiency [5] and three others have been anecdotally characterized previously [6,7]. Here, we report the molecular basis of XIIIA deficiency in eight additional FXIII deficient families living in Italy.…”

“…Factor XIIIA deficiency in Italy had been previously characterized in eight families only [5][6][7]. We have characterized seven additional families and reinvestigated a previous family in which only a single mutation had been identified [7].…”

“…The coding region, intron-exon boundaries and 5¢ and 3¢ untranslated regions of the F13A gene encoding the A subunit (GenBank accession number NT 034880) were amplified by polymerase chain reaction (PCR) and sequenced as previously described [5]. Data obtained from the Sequence Analysis Software (Applied Biosystems, Foster City, CA, USA) were aligned with the wild-type sequence (GenBank Database) for mismatch detection.…”

Homozygous intronic mutation leading to inefficient transcription combined with a novel frameshift mutation in F13A1 gene causes FXIII deficiency

“…1-2 Mutations in the A or B subunit gene are responsible for the disorder. [1][2][3][4][5][6][7] The disorder usually results from mutations in subunit A, but is occasionally attributable to mutations in subunit B (http:// www.hgmd.cf.ac.uk/ and http://www.f13-database.de). We describe two novel mutations in a Chinese FXIII-deficient family and characterize a novel mechanism involved in regulating the expression of the F13A1 gene.…”