Molecular analysis of the most prevalent mutations of the FANCA and FANCC genes in Brazilian patients with Fanconi anaemia

Clinical and cytogenetic profile of Fanconi anemia diagnosed after implementation of mitomycin C cytogenetic test in the state of Pernambuco, Brazil

INTRODUCTION

Fanconi anemia (FA) is a rare autosomal recessive disease characterized by chromosomal instability and increased predisposition to malignancy. The diagnosis of FA requires clinical evaluation, confirmation of chromosomal fragility and/or analysis of genetic mutations. Therefore, this study aims to identify the clinical profile of patients with FA in the state of Pernambuco, Brazil.

METHOD

We analyzed 100 individuals referred from the major hematology and bone marrow (BM) transplant centers in the state of Pernambuco, Brazil, between the years 2018 and 2022. The diagnosis of FA was performed using the mitomycin C chromosomal fragility test, clinical data and classical and molecular cytogenetic analyses.

RESULTS

We enrolled a total of 16 patients with FA to comprise this study. Most of these individuals (87.5%) came from the Agreste and Sertão regions of Pernambuco. We observed a slight female prevalence of FA (1.3:1). The primary clinical and laboratory findings were café au lait spots (62.5%) and bone abnormalities (53%, mainly thumb deformities [40%]). We performed BM cytogenetic analysis for eight patients - seven showed no chromosomal abnormalities and one presented the karyotype 47,XY,+21 [15].

CONCLUSIONS

Our results are important to promote public health measures for the early diagnosis of FA, as well as to foster the engagement of a multidisciplinary group in the treatment of this disease.

Novel FANCA mutation in the first fully-diagnosed patient with Fanconi anemia in Polish population - case report

BACKGROUND

Fanconi anemia is a rare genetic disorder caused by mutations in genes which protein products are involved in replication, cell cycle control and DNA repair. It is characterized by congenital malformations, bone marrow failure, and high risk of cancer. The diagnosis is based on morphological and hematological abnormalities such as pancytopenia, macrocytic anaemia and progressive bone marrow failure. Genetic examination, often very complex, includes chromosomal breakage testing and mutational analysis.

CASE PRESENTATION

We present a child with clinical diagnosis of Fanconi anemia. Although morphological abnormalities of skin and bones were present from birth, diagnosis was only suspected at the age of 8. Chromosome breakage test in patient's lymphocytes showed increased level of aberrations (gaps, chromatid breaks, chromosome breaks, radial figures and rearrangements) compared to control. Next generation sequencing revealed presence of two pathogenic variants in FANCA gene, one of which was not previously reported.

CONCLUSIONS

The article provides additional supportive evidence that compound biallelic mutations of FANCA are associated with Fanconi anemia. It also illustrates the utility of combination of cytogenetic and molecular tests, together with detailed clinical evaluation in providing accurate diagnosis of Fanconi anemia. This report, to the best of our knowledge, describes the first fully diagnosed FA patient in Polish population.

Whole exome sequencing identifies compound heterozygous variants of CR2 gene in monozygotic twin patients with common variable immunodeficiency

Objectives:

A pair of female Malay monozygotic twins who presented with recurrent upper respiratory tract infections, hepatosplenomegaly, bronchiectasis and bicytopenia were recruited in this study. Both patients were suspected with primary immunodeficiency diseases. However, the definite diagnosis was not clear due to complex disease phenotypes. The objective of this study was to identify the causative gene mutation in these patients.

Methods:

Lymphocyte subset enumeration test and whole exome sequencing were performed.

Results:

We identified a compound heterozygous CR2 mutation (c.1916G>A and c.2012G>A) in both patients. These variants were then confirmed using Sanger sequencing.

Conclusion:

Whole exome sequencing analysis of the monozygotic twins revealed compound heterozygous missense mutations in CR2.

Características clínicas de pacientes com anemia de Fanconi

OBJETIVO: Verificar as características clínicas de pacientes com anemia de Fanconi (AF) diagnosticados em um Serviço de Genética Clínica. MÉTODOS: O estudo incluiu todos os pacientes atendidos no Serviço de Genética Clínica da Universidade Federal de Ciências da Saúde de Porto Alegre e Complexo Hospitalar Santa Casa de Porto Alegre, entre 1975 e 2008, com suspeita clínica de AF submetidos ao estudo de quebras cromossômicas com o uso de diepoxi-butano (DEB) a partir do sangue periférico. Realizou-se uma análise retrospectiva das características clínicas dos pacientes, a partir de um levantamento sistemático dos seus prontuários médicos. RESULTADOS: A amostra foi composta de 17 pacientes, sendo que em sete o diagnóstico de AF foi confirmado. Os pacientes com AF caracterizaram-se por um fenótipo amplo, oscilando desde um quadro de pancitopenia sem dismorfias até a presença de múltiplas malformações sem alterações hematológicas. Certos achados, como face triangular, orelhas em abano e manchas café com leite foram frequentes e encontrados apenas nos indivíduos com AF. História de equimoses, hematomas, petéquias, infecções e linfadenopatias foi comum entre os indivíduos desse grupo. Por outro lado, alterações neurológicas foram observadas apenas em pacientes sem AF. Consanguinidade foi verificada em apenas um paciente, que apresentava AF. CONCLUSÕES: Apesar das limitações do estudo, os achados ilustram a grande variabilidade fenotípica observada na AF, o que torna seu diagnóstico clínico um desafio. No entanto, alguns achados específicos podem servir de pistas para sua detecção. A identificação precoce desses indivíduos é fundamental para o seu manejo adequado.