Interstitial deletion of 5q33.3q35.1 in a boy with severe mental retardation / 소아과

Constitutional interstitial deletions of the long arm of chromosome 5 (5q) are quite rare, and the corresponding phenotype is not yet clearly delineated. Severe mental retardation has been described in most patients who present 5q deletions. Specifically, the interstitial deletion of chromosome 5q33.3q35.1, an extremely rare chromosomal aberration, is characterized by mental retardation, developmental delay, and facial dysmorphism. Although the severity of mental retardation varies across cases, it is the most common feature described in patients who present the 5q33.3q35.1 deletion. Here, we report a case of a de novo deletion of 5q33.3q35.1, 46,XY,del(5)(q33.3q35.1) in an 11-year-old boy with mental retardation; to the best of our knowledge this is the first case in Korea to be reported. He was diagnosed with severe mental retardation, developmental delay, facial dysmorphisms, dental anomalies, and epilepsy. Chromosomal microarray analysis using the comparative genomic hybridization array method revealed a 16-Mb-long deletion of 5q33. 3q35.1(156,409,412-172,584,708)x1. Understanding this deletion may help draw a rough phenotypic map of 5q and correlate the phenotypes with specific chromosomal regions. The 5q33.3q35.1 deletion is a rare condition; however, accurate diagnosis of the associated mental retardation is important to ensure proper genetic counseling and to guide patients as part of long-term management.

A Case of Myelodysplastic Syndrome Associated with an Isolated del(5q) Chromosomal Abnormality Showing Poor Prognosis

Typical myelodysplastic syndrome (MDS) associated with isolated del(5q) consists of an interstitial deletion of the band between q13 and q33 on chromosome 5. Generally, patients with isolated deletion 5q have better outcomes than those who have the deletion 5q with additional karyotypic abnormalities. Here we report a 47 year-old female with an isolated del(5q) chromosomal abnormality with an atypical breakpoint of 5q11q35 and rapid progression to acute leukemia, which had an exceptionally poor outcome. The peripheral blood revealed pancytopenia and occasional giant platelets, and the patient had hypercellular bone marrow with 4.8% blasts, as well as dysmegakaryopoiesis and dyserythropoiesis. Cytogenetically, the patient was del(5q)(q11.2q35)[18]/46,XX[2], showing that her deleted region was larger than that found for typical del 5q syndrome. Three months later, the patient presented with acute myelomonocytic leukemia with multilineage dysplasia. The cytogenetic findings were identical. Two months after allogeneic bone marrow transplantation, the patient died from severe graft-versus host disease.