A comprehensive molecular study identified 12 complementation groups with 56 novel FANC gene variants in Indian Fanconi anemia subjects

Fanconi anemia (FA) is a rare autosomal or X-linked genetic disorder characterized by chromosomal breakages, congenital abnormalities, bone marrow failure (BMF), and cancer. There has been a discovery of 22 FANC genes known to be involved in the FA pathway. This wide number of pathway components makes molecular diagnosis challenging for FA. We present here the most comprehensive molecular diagnosis of FA subjects from India. We observed a high frequency (4.42 ± 1.5 breaks/metaphase) of chromosomal breakages in 181 FA subjects. The major clinical abnormalities observed were skin pigmentation (70.2%), short stature (46.4%), and skeletal abnormalities (43.1%), along with a few minor clinical abnormalities. The combination of Sanger sequencing and Next Generation Sequencing could molecularly characterize 164 (90.6%) FA patients and identified 12 different complementation groups [FANCA (56.10%), FANCG (16.46%), FANCL (12.80%), FANCD2 (4.88%), FANCJ (2.44%), FANCE (1.22%), FANCF (1.22%), FANCI (1.22%), FANCN (1.22%), FANCC (1.22%), FANCD1 (0.61%) and FANCB (0.61%)]. A total of 56 novel variants were identified in our cohort, including a hotspot variant: a deletion of exon 27 in the FANCA gene and a nonsense variant at c.787 C>T in the FANCG gene. Our comprehensive molecular findings can aid in the stratification of molecular investigation in the diagnosis and management of FA patients.

Expanding the FANCO/RAD51C associated phenotype: Cleft lip and palate and lobar holoprosencephaly, two rare findings in Fanconi anemia

Fanconi anemia is a rare chromosome instability disorder with a highly variable phenotype. In the antenatal and neonatal periods, the diagnosis is usually suggested by the presence of typical congenital abnormalities such as intrauterine growth retardation, microcephaly and radial ray defects. We report a newborn female with a prenatal diagnosis of Fanconi anemia, complementation group O (FANCO). Antenatal ultrasounds identified symmetrical intrauterine growth retardation, complex heart defect as well as brain anomalies, overlapping fingers and cleft lip and palate. Imperforate anus was detected after birth. Compound heterozygous RAD51C variants c. [571+5G > A]; [c.935G > A] were detected by prenatal whole exome sequencing and cellular hypersensitivity to DNA interstrand crosslinking agents (DEB, MMC) was confirmed after birth. With only one previously described homozygous RAD51C variant to date, our findings expand the phenotypic spectrum of FANCO and suggest it should be part of the antenatal differential diagnosis for trisomy 13 and 18, due to the presence of atypical findings such as cleft lip and palate, holoprosencephaly, growth restriction and overlapping fingers.