Clinicohematological correlation and chromosomal breakage analysis in suspected Fanconi anemia patients of India

An experience with 124 cases of fanconi anemia: clinical spectrum, hematological parameters and chromosomal breakage analysis

BACKGROUND

Fanconi anemia is an inherited bone marrow failure syndrome characterized by somatic abnormalities and an increased predisposition to malignancies.

OBJECTIVE

To determine the clinical spectrum and evaluate the hematological parameters as well as highlight diagnosis by chromosomal breakage analysis of Fanconi anemia patients.

MATERIAL AND METHODS

A total of 124 patients were diagnosed as having Fanconi anemia from August 2014 to May 2020 at Armed Forces Institute of Pathology, Rawalpindi, Pakistan. Clinical details, somatic abnormalities, radiological findings, lab parameters and result of chromosomal breakage analysis were noted and analyzed.

RESULTS

One hundred and twenty four (14.29%) were diagnosed as having Fanconi anemia (FA) on chromosomal breakage test. Median age was 09 years 06 months. Male to female ratio was 1.9:1. Six of these patients exhibited mosaicism and were classified as FA mosaic. Somatic abnormalities were detected in 74 (59.7%) patients; the most common being skeletal abnormalities and short stature.

CONCLUSION

Chromosomal breakage analysis is a cost-effective method for diagnosis of Fanconi anemia. Early diagnosis is pertinent for proper treatment and long term prognosis.

Chromosomal Breakage in Fanconi Anemia and Consanguineous Marriages: A Social Dilemma for Developing Countries

Introduction A clear picture of the prevalence of Fanconi anemia is not known due to limited studies and research of the subject. This study will detect the frequency of positive chromosomal breakage in pediatric aplastic patients and provide the evidence-based guidelines which help in consideration of appropriate treatment and awareness to the society. Methods A total of 104 aplastic anemia patients were recruited of age <18 years whose samples were tested for chromosomal breakage with mitomycin C (MMC). History of consanguinity between parents were documented for all the patients referred to us. Result Out of 104 diagnosed aplastic anemia patients, 35 (33.7%) patients were found to be Fanconi positive. Mean age of all hypoplastic patients for aplastic anemia and Fanconi anemia was 10.7 ± 4.5 and 10.6 ± 3.5, respectively. Male preponderance was found to be higher (64, 61.5%) as compared to females (40, 38.5%) in aplastic patients. The male to female ratio was observed as 2.5:1 in Fanconi patients while 1.3:1 in non-Fanconi aplastic patients. Parental consanguinity was observed in 33 (94.2%) with Fanconi anemia. Conclusion Fanconi anemia accounts for significant number of patients with hypoplastic bone marrow, therefore consanguineous marriages should be avoided through mass education in Pakistan.

Incidence of Fanconi anaemia in phenotypically normal aplastic anaemia patients in West Bengal

OBJECTIVES

Fanconi anaemia (FA) is a rare inherited bone marrow failure and autosomal recessive blood disorder. FA patients have a higher risk of cancer, including acute myeloid leukaemia and squamous cell carcinoma. Maximum, but not all, affected individuals have one or more somatic abnormalities, including skin, skeletal, genitourinary, gastrointestinal, cardiac and neurological anomalies, etc. Positive stress cytogenetics has immense implications for the treatment and management of FA. The aim of our study was to find out the incidence of FA in the population of phenotypically normal aplastic anaemia (AA) patients in West Bengal.

METHODS

Ethical clearances were obtained from the corresponding institutional committees. A total of 117 AA cases was selected. Stress cytogenetics was performed from peripheral venous blood (PVB) samples of 63 AA patients (age ≤ 50 years) and 63 age- and sex-matched healthy individual (control) using Mitomycin C (MMC).

RESULTS

Out of 63 AA patients, 6 (9.25%) cases showed positive stress cytogenetics suggestive of FA, which is statistically significant (p-value - 0.000532), analysed by chi-square test.

DISCUSSION

A considerable percentage of patients showing sensitivity towards MMC, even if they are phenotypically normal and did not have any distinguishable features which are generally found in FA.

CONCLUSION

This observation may indicate that stress cytogenetics analysis of phenotypically normal AA patients (≤50 years) is essential for the improvement of the treatment procedure.

Cytogenetic study is not essential in patients with aplastic anemia

Depending on contemporary treatment approach of aggressive immunosuppression, Aplastic Anemia (AA) is caused by immunological destruction of otherwise normal hematopoietic stem cells. The aim was to summarize the cytogenetic abnormalities in AA patients and the frequency of Fanconi Anemia (FA) in morphologically normal AA patients in eastern India. Ethical clearances were obtained from both institutions involved in this study. Out of 72800 patients attending the outpatient department, 520 pancytopenia patients were screened for AA after Bone marrow (BM) aspiration and biopsy. Samples were collected from 117 cases in 3 phases. 51 peripheral venous blood (PVB) samples in the first phase, 19 BM & PVB paired samples in the second phase and 47 BM samples in third phase were collected followed by leukocyte and/or BM stem cell culture. Next GTG banding and karyotyping were performed. PVB was collected from 63 (< 50 years) AA patients and stress cytogenetics was done to diagnose FA. In the first phase of the study, out of 51 PVB samples, 1 (1.96%) showed a unique chromosomal abnormality, i.e. 45,XY,rob(14:21)(p10:q10)[20]. In the second phase of study, among 19 BM & PVB paired samples, 1 (5.26%) showed abnormal karyotype i.e. 45,X,-Y[3]/46,XY[47]. In the third phase of the study, 47 BM samples showed normal karyotype. Only 6 (9.52%) cases were found positive for stress cytogenetics. A negligible percentage showing cytogenetic abnormality in such a considerable number of AA cases indicates that routine cytogenetic analysis of AA patient is not essential. A significant percentage was positive for stress cytogenetics; suggestive for FA, even the patients were morphologically normal.

Screening for mutations in two exons of FANCG gene in Pakistani population

BACKGROUND

Fanconi anemia is a rare autosomal recessive disorder of genetic instability. It is both molecularly and clinically, a heterogeneous disorder. Its incidence is 1 in 129,000 births and relatively high in some ethnic groups. Sixteen genes have been identified among them mutations in FANCG gene are most common after FANCA and FANCC gene mutations.

OBJECTIVE

To study mutations in exon 3 and 4 of FANCG gene in Pakistani population.

METHODS

Thirty five patients with positive Diepoxybutane test were included in the study. DNA was extracted and amplified for exons 3 and 4. Thereafter Sequencing was done and analyzed for the presence of mutations.

RESULTS

No mutation was detected in exon 3 whereas a carrier of known mutation c.307+1 G>T was found in exon 4 of the FANCG gene.

CONCLUSION

Absence of any mutation in exon 3 and only one heterozygous mutation in exon 4 of FANCG gene points to a different spectrum of FA gene pool in Pakistan that needs extensive research in this area.

A case report and literature review of Fanconi Anemia (FA) diagnosed by genetic testing

Fanconi anemia (FA) is a genetically heterogeneous rare autosomal recessive disorder characterized by congenital malformations, hematological problems and predisposition to malignancies. The genes that have been found to be mutated in FA patients are called FANC. To date 16 distinct FANC genes have been reported. Among these, mutations in FANCA are the most frequent among FA patients worldwide which account for 60- 65%. In this study, a nine years old male child was brought to our hospital one year ago for opinion and advice. He was the third child born to consanguineous parents. The mutation analyses were performed for proband, parents, elder sibling and the relatives [maternal aunt and maternal aunt’s son (cousin)]. Molecular genetic testing [targeted next-generation sequencing (MiSeq, Illumina method)] was performed by mutation analysis in 15 genes involved. Entire coding exons and their flanking regions of the genes were analysed. Sanger sequencing [(ABI 3730 analyzer by Applied Biosystems)] was performed using primers specific for 43 coding exons of the FANCA gene. A novel splice site mutation, c.3066 + 1G > T, (IVS31 + 1G > T), homozygote was detected by sequencing in the patient. The above sequence variant was identified in heterozygous state in his parents. Further, the above sequence variant was not identified in other family members (elder sibling, maternal aunt and cousin). It is concluded that genetic study should be done if possible in all the cases of suspected FA, including siblings, parents and close blood relatives. It will help us to plan appropriate treatment and also to select suitable donor for hematopoietic stem cell transplantation and to plan for genetic counseling. In addition to the case report, the main focus of this manuscript was to review literature on role of FANCA gene in FA since large number of FANCA mutations and polymorphisms have been identified.