Browsing by Author "Altunoglu, Umut"

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Clinical and Molecular Characterization of Fanconi Anemia Patients in Turkey
(KARGER, 2020-01-01) Toksoy, Guven; Uludag Alkaya, Dilek; Bagirova, Gulendam; Avci, Sahin; Aghayev, Agharza; Gunes, Nilay; Altunoglu, Umut; Alanay, Yasemin; Basaran, Seher; Berkay, Ezgi G.; Karaman, Birsen; Celkan, Tiraje T.; Apak, Hilmi; Kayserili, Huelya; Tuysuz, Beyhan; Uyguner, Zehra O.
Fanconi anemia (FA) is a rare multigenic chromosomal instability syndrome that predisposes patients to life-threatening bone marrow failure, congenital malformations, and cancer. Functional loss of interstrand cross-link (ICL) DNA repair system is held responsible, though the mechanism is not yet fully understood. The clinical and molecular findings of 20 distinct FA cases, ages ranging from perinatal stage to 32 years, are presented here. Pathogenic variants in FANCA were found responsible in 75\%, FANCC, FANCE, FANCJ/BRIP1, FANCL in 5\%, and FANCD1/BRCA2 and FANCN/PALB2 in 2.5\% of the subjects. Altogether, 25 different variants in 7 different FA genes, including 10 novel mutations in FANCA, FANCN/PALB2, FANCE, and FANCJ/BRIP1, were disclosed. Two compound heterozygous germline cases were mosaic for one allele, revealing that the incidence of reverse mutations may not be uncommon in FA. Another case with de novo FANCD1/BRCA2 and paternally inherited FANCN/PALB2 pathogenic alleles at first glance suggested a digenic inheritance, because the presence of a second pathogenic variant in the unexamined regions of FANCD1/BRCA2 and FANCN/PALB2 were exluded by sequencing and deletion/duplication analysis. A better understanding of the complexity of the FA genotype may provide further access to undiscovered ICL components and apparently dispensable cellular pathways where FA proteins may play important roles.
Novel MASP1 mutations are associated with an expanded phenotype in 3MC1 syndrome
(BIOMED CENTRAL LTD, 2015-01-01) Atik, Tahir; Koparir, Asuman; Bademci, Guney; Foster II, Joseph; Altunoglu, Umut; Mutlu, Gul Yesiltepe; Bowdin, Sarah; Elcioglu, Nursel; Tayfun, Gulsen A.; Atik, Sevinc Sahin; Ozen, Mustafa; Ozkinay, Ferda; Alanay, Yasemin; Kayserili, Hulya; Thiel, Steffen; Tekin, Mustafa
Background: 3MC1 syndrome is a rare autosomal recessive disorder characterized by intellectual disability, short stature and distinct craniofacial, umbilical, and sacral anomalies. Five mutations in MASP1, encoding lectin complement pathway enzymes MASP-1 and MASP-3, have thus far been reported to cause 3MC1 syndrome. Only one previously reported mutation affects both MASP-1 and MASP-3, while the other mutations affect only MASP-3. Methods: We evaluated six unrelated individuals with 3MC1 syndrome and performed Sanger sequencing for all coding exons of MASP1. We also measured complement lectin and alternative pathway activities in an affected individual's serum. Results: We found two novel splice site mutations, c.1012-2A > G in one and c.891 + 1G > T in two probands, and three novel missense mutations, c.1451G > A (p.G484E), c.1657G > A (p.D553N), and c.1987G > T (p.D663Y). Missense mutations affect only MASP-3, while splice site mutations affect both MASP-1 and MASP-3. In a proband who is homozygous for c.891 + 1G > T, we detected a total lack of lectin complement pathway activity and a 2.5-fold lower alternative pathway activity. The phenotype observed in patients whose both MASP-1 and MASP-3 are affected and in those whose only MASP-3 is affected does not appear to be different. We observed structural brain abnormalities, neonatal tooth, a vascular anomaly and a solid lesion in liver as novel phenotypic features of 3MC1 syndrome. Conclusion: Novel mutations and additional phenotypic features expand the genotypic and phenotypic spectrum of 3MC1 syndrome. Although patients with MASP-1 dysfunction in addition to disrupted MASP-3 have an altered complement system, their disease phenotype is not different from those having only MASP-3 dysfunction.