Cytogenetic findings in Polish patients with suspected Fanconi anemia.

BACKGROUND: The high sensitivity of cells of Fanconi anemia (FA) patients to DNA cross-linking agents (clastogens), such as mitomycin C (MMC), was used as a screening tool in Polish children with clinical suspicion of FA. OBJECTIVES: The aim of the study was to compare chromosome fragility between 3 groups, namely non-FA, possible mosaic FA and FA patients. MATERIAL AND METHODS: The study included 100 children with hematological manifestations and/or congenital defects characteristic of FA, and 100 healthy controls. Blood samples obtained from participants were analyzed using an MMC-induced chromosomal breakage test. RESULTS: Patients with clinical suspicion of FA were divided into 3 subgroups based on the MMC test results, namely FA, possible mosaic FA and non-FA. Thirteen out of 100 patients had a true FA cellular phenotype. The mean value of MMC-induced chromosome breaks/cell for FA patients was higher than for non-FA patients (6.67 ±3.92 compared to 0.23 ±0.18). In addition, the percentage of cells with spontaneous aberrations was more than 9 times higher in FA patients than in non-FA patients. CONCLUSIONS: Our results confirmed that the MMC sensitivity test distinguishes between individuals affected by FA, those with possible somatic mosaicism, and patients with bone marrow failure for other reasons, who were classified as non-FA in the first diagnostic step. However, a definitive differential diagnosis requires follow-up mutation testing and chromosome breakage analysis of skin fibroblasts.

The Levels of Pregnancy-Associated Plasma Protein (PAPP-A) and Chorionic Gonadotropin (ß-hCG) in the Blood Serum of Women with Hypothyroidism in the 1st Trimester of Pregnancy.

Introduction: Hypothyroidism occurs in pregnant women at a rate of 0.3% to 3%. The deficiency of thyroid hormones during pregnancy can lead to an increased risk of pregnancy complications and poor health of the child, particularly affecting its psychomotor development due to the intensive growth of the nervous system during gestation. The study attempted to establish the median concentrations of pregnancy-associated plasma protein PAPP-A and the free subunit of human chorionic gonadotropin ß-hCG in women with hypothyroidism in the 1st trimester of pregnancy. Objective: The study attempted to establish the median concentrations of pregnancy-associated plasma protein PAPP-A and the free subunit of human chorionic gonadotropin ß-hCG in women with hypothyroidism in the 1st trimester of pregnancy. Patients and methods: The study included 210 pregnant women between 11 and 13.6 weeks of pregnancy; 105 women were diagnosed with hypothyroidism before or during pregnancy, and 105 women of a similar body weight and gestational age had normal thyroid function.The measurements of the pregnancy parameters studied were performed using the DELFIA® Xpress system. Results: Differences in the multiples of the median of the PAPP-A and ß-hCG levels between women with hypothyroidism and healthy women were observed. Conclusion: Introducing correction for patients with hypothyroidism during non-invasive biochemical prenatal testing may allow obtaining more reliable results that would be the basis for referral to invasive procedures.

Next-generation sequencing reveals novel variants and large deletion in FANCA gene in Polish family with Fanconi anemia.

BACKGROUND: Fanconi anemia (FA) is the most common inherited bone marrow failure syndrome. However, establishing its molecular diagnosis remains challenging. Chromosomal breakage analysis is the gold standard diagnostic test for this disease. Nevertheless, molecular analysis is always required for the identification of pathogenic alterations in the FA genes. RESULTS: We report here on a family with FA diagnosis in two siblings. Mitomycin C (MMC) test revealed high level of chromosome breaks and radial figures. In both children, array-Comparative Genomic Hybridization (aCGH) showed maternally inherited 16q24.3 deletion, including FANCA gene, and next generation sequencing (NGS) disclosed paternally inherited novel variants in the FANCA gene-Asn1113Tyr and Ser890Asn. A third sibling was shown to be a carrier of FANCA deletion only. CONCLUSIONS: Although genetic testing in FA patients often requires a multi-method approach including chromosome breakage test, aCGH, and NGS, every effort should be made to make it available for whole FA families. This is not only to confirm the clinical diagnosis of FA in affected individuals, but also to enable identification of carriers of FA gene(s) alterations, as it has implications for diagnostic and genetic counselling process.

Clinical Importance of aCGH in Genetic Counselling of Children with Psychomotor Retardation.

Introduction: The X and Y chromosomes are responsible for the determination and differentiation of the gonads, and their numerical and structural abnormalities may cause the abnormal development of secondary sex characteristics. The presence of abnormalities concerning X chromosome can also contribute to many genetically heterogeneous diseases associated with cognitive impairment and intellectual disability. Purpose: This study shows the effect of aberrations of the maternal X chromosome on the abnormal development of the child. Patients and Methods: Ten women aged 26 to 40 years were consulted in genetic counselling clinic and subsequently subjected to cytogenetic and molecular tests due to abnormal psychomotor development of their children, in whom structural aberrations of the X chromosome had been detected. Results: Two women were diagnosed with changes in karyotype: 46,X,der(X)t(X;Y)(p22.3;q11.2) in one and 46,X,inv(X)(p21.2q13). Five women were diagnosed with microduplications in the short arm of the X chromosome; dupXp22.31 in one, and in four women dupXp22.33. The remaining three women were diagnosed with duplication in the long arm of the X chromosome; dupXq25 in one and dupXq26.3 in two women. Conclusion: Genetic analysis of the X chromosome, based on cytogenetic and molecular methods of the highest available resolution, is extremely important in women with reproductive failure. These methods allow establishing accurately the breakpoints and rearrangements in chromosomes, and assessment of the copy number variation (CNV) can explain phenotypic variability with apparently similar aberrations. A more precise characterization of the alterations is necessary for the correct genetic diagnosis, as well as determination of the carrier status and genetic risk in family members.

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.

Prenatal identification of partial 3q duplication syndrome.

BACKGROUND: The 3q duplication syndrome is a result of duplication of a large fragment of the long arm of chromosome 3, mainly 3q21-qter, and in most cases it is diagnosed only after birth. The phenotypic consequences resulting from genetic imbalance are an important source of information for genetic counselling, especially in prenatal diagnostics. However, in most cases it is impossible to define them precisely because the final clinical presentation is a result of an overlap, usually due to different sizes of deletions and/or duplications not only chromosome 3 but also of translocation partner chromosome. In this article, we present a prenatal diagnosis of the 3q duplication syndrome in a foetus, arising from a balanced insertion ins (7,3)(q21.2;q12.3q29) carried by the mother. CASE PRESENTATION: The article presents a case of a 29-year-old woman referred to the Genetic Outpatient Clinic for consultation in the 12th week of her fifth pregnancy with a diagnosis of generalised hydrops foetalis. The analysis of karyotype using GTG technique and FISH allowed diagnosis of a balanced aberration in the mother, and determined the type of chromosomal rearrangement, which allowed the identification of the origin of the additional genetic material in the foetus and the previous malformed child of the same couple. The use of molecular karyotyping techniques (FISH and aCGH) allowed a precise determination of the size of the imbalanced fragments in the affected siblings. CONCLUSIONS: The aCGH technique is particularly valuable for the diagnostics of submicroscopic deletions and duplications, if no imbalanced chromosomal aberrations are detected by routine cytogenetic tests. It is also a valuable technique for identifying and fully characterizing genetic material of unknown origin, which can't be identified using routine cytogenetic techniqes. However, it does not allow identification of balanced aberrations in carriers.