Efficient detection of factor IX mutations by denaturing high-performance liquid chromatography in Taiwanese hemophilia B patients, and the identification of two novel mutations

A de novo int22h-1/int22h-2-flanked Xq28 deletion-associated preferential X-inactivation in a female with severe hemophilia B

A 5-year-old female diagnosed with severe hemophilia B began experiencing frequent muscular and joint bleeds at 19 months old. Molecular studies, including Sanger sequencing, Giemsa banding, human androgen receptor (HUMARA) assay, array-based comparative genomic hybridization (aCGH), whole-exome sequencing (WES), and multiplex ligation-dependent probe amplification (MLPA), revealed a heterozygous factor IX (F9) intron 3 substitution (c.277+1G>T) inherited from her mother and a de novo heterozygous 441 kb deletion in the Xq28 region, which flanked intron 22 homologous regions 1 (int22h1) and 2 (int22h2). This rare genetic profile explains her severe phenotype and guides hereditary consultation for family planning.

Evolution of congenital haemophilia care in Taiwan

Haemophilia care in Taiwan has come a long way over the past 35 years, from the absence of specialised haemophilia treatment centres before 1984 to the establishment of treatment centers in the majority of medical centers, the listing of haemophilia as a catastrophic illness with full treatment reimbursement by the Taiwan National Health Insurance (NHI), and the implementation of full NHI coverage for prophylaxis therapy. This has led to outcome improvements such as reduced bleed-related morbidity and mortality, fewer viral infections, and enhanced overall multi-modality care. Most people with haemophilia (PWH) are now able to live normal, active lives. Early diagnosis has improved through increased awareness, physician education, and prenatal diagnosis; while comprehensive care, including state of the art rehabilitation and orthopaedic management for haemophilic arthropathy, eradication therapy for chronic hepatitis C, and better treatments for human immunodeficiency virus, allows PWH to enjoy a better quality of life and improved survival. Efforts are now being made to raise prophylaxis rates through full NHI reimbursement and the use of extended half-life recombinant factor products. Overall, Taiwan has made great strides in haemophilia care and we would like to share these experiences for the benefit of all healthcare providers involved in haemophilia care.

Defining the molecular pathology and consequent phenotypes in Egyptian HB patients

BACKGROUND

Hemophilia B (HB) (also known as Christmas disease) is a rare X-linked recessive disorder characterized by spontaneous or prolonged hemorrhages caused by mutations in Factor 9 (F9) gene leading to deficient or defective coagulation F9. Our study aimed at identifying the causative mutations within a sample of HB Egyptian patients. The present study comprised clinical data of eleven HB patients descending from six unrelated families and a seventh family including a carrier mother with a history of deceased HB sibling. Sequencing of F9 gene was performed.

RESULTS

The study revealed four mutations; two missense NM_000133.3:c.676C>G, (P.Arg226Gly) and NM_000133.3:c.1305T>G, (p.Cys435Trp), and two nonsense mutations NM_000133.3:c.880C>T, (p.Arg294*) and NM_000133.3:c.1150C>T, (p.Arg384*), identified mutations spanned exons 6 and 8 of which a total of three mutations are located in hotspot exon 8 of F9 gene.

CONCLUSIONS

Reviewing the literature, this is the first molecular analysis of F9 gene in HB Egyptian patients. Consistent genotype/phenotypic severity correlation could be concluded, helping proper genetic counseling and prenatal decision taking.