RESUMO
We genetically evaluated 260 dystrophinopathy patients from Turkey. Karyotyping as an initial test in female patients, followed stepwise by multiplex ligation-dependent probe amplification and by targeted next-generation sequencing of DMD revealed definitive genetic diagnoses in 214 patients (82%), with gross deletions/duplications in 153 (59%), pathogenic sequence variants in 60 (23%), and X-autosome translocation in one. Seven of the gross and 27 of the sequence variants found novel. In silico prediction, co-segregation and transcript assays supported the pathogenic nature of the novel silent (p.Lys534=) and the splice site (c.4345-12C>G) alterations. From a total of 189 singleton cases, 154 (82%) had pathogenic alterations. From 138 of those who had maternal carrier testing, 68 out of 103 (66%) showed gross and 11 out of 35 (31%) showed small pathogenic variants. This suggests that the de novo occurrences in DMD appear approximately 2.1 times more frequently in meiotic unequal crossing-over than in uncorrected replication errors. Our study also disclosed three mothers as obligate gonadal mosaic carriers. Family-based investigation of dystrophinopathy patients is crucial for the ascertainment of novel or rare variants and also for counseling and follow-up care of the families.
Assuntos
Distrofina/genética , Aconselhamento Genético , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/fisiopatologia , Adulto , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Masculino , Mutação , Fenótipo , Análise de Sequência de DNA , Turquia , Adulto JovemRESUMO
We report on a boy born to consanguineous parents, who had hypertelorism, a broad nasal bridge, ridge and tip, bifid nasal tip, cleft alae nasi, broad columella, unilateral preauricular tag, shallow labiogingival sulcus, and bilateral large parietal foramina. Cranial MRI revealed a kinked corpus body and small cerebellar vermis. Molecular analysis uncovered a homozygous c.673C > G (p.Q225E) mutation in ALX4 gene. We compare the relatively mild phenotype in the patient to the more marked phenotype described in other patients with homozygous ALX4 mutations, and to the phenotypes in patients with mutations in other ALX genes.
