Abstract
BackgroundDistal 8p duplication is rare but clinically significant. Duplication syndrome results in variable phenotypes, such as developmental delay, intellectual disability, and malformation of the heart. We aimed to provide a better understanding of the phenotypes by studying duplication and its effects in a single family.MethodsIn a family with a previously induced labor (second fetus) at 12 weeks gestation due to increased nuchal translucency (3.5 mm), copy number variation sequencing (CNV-seq) revealed a 16.22 Mb deletion of 8p23.3p22. For their subsequent pregnancy, the family requested a prenatal diagnosis as well as CNV-seq, karyotyping and FISH testing of all family members.ResultsThe first and third children were found to have a 16.22 Mb duplication of 8p23.3p22, containing the 8p23.1 duplication syndrome region. The duplication was inherited from their father, a carrier with a translocation of 8p22 and 22q13. We confirmed that the duplication site was located on chromosome 22q13 by combining the results of CNV-seq, karyotype and FISH. The first child is a 7.5-year-old boy. At one month old, he was diagnosed with a ventricular septal defect and treated surgically at age four. His growth and intelligence developed well, and he performed well in school. His primary issue is an inability to distinguish between the blade alveolars and retroflexes in speech. The third fetus had a normal ultrasound index from beginning until birth. The family elected to continue the pregnancy, and the baby was born healthy, providing us the opportunity to evaluate the effects of 8p23.3p22 duplication by comparison with the brother.ConclusionOur study makes a significant contribution to the literature because this relatively rare condition can have significant phenotypical consequences, and an understanding of the inheritance and variability of phenotypes caused by this mutation is essential to an increased understanding of the condition.
Highlights
IntroductionDuplication syndrome results in variable phenotypes, such as developmental delay, intellectual disability, and malformation of the heart
Distal 8p duplication is rare but clinically significant
Short tandem repeat (STR) markers were used for chromosome 21, chromosome 18, chromosome 13, and sex chromosomes X and Y according to the process described previously
Summary
Duplication syndrome results in variable phenotypes, such as developmental delay, intellectual disability, and malformation of the heart. The phenotypes vary greatly, from multiple deformities to solely intellectual disabilities. This heterogeneity adds to the challenges of evaluating the condition and providing prenatal genetic counseling to families. Only three cases (8:10,001– 12,655,629, 12.65 Mb) contain gene duplication regions that are close to and smaller than the region studied in our report (8:160,000–16,380,000, 16.22 Mb). The DECIPHER IDs are 392,337, 395,697, and 399,307 (https://decipher.sanger.ac.uk/) One of these cases was due to a parental unbalanced rearrangement, another was due to maternal inheritance, with the gene being constitutive in the mother, and the cause of the last case was unknown
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