Aberrant splicing contributes to severe α-spectrin-linked congenital hemolytic anemia.

The etiology of severe hemolytic anemia in most patients with recessive hereditary spherocytosis (rHS) and the related disorder hereditary pyropoikilocytosis (HPP) is unknown. Whole exome sequencing of DNA from probands of 24 rHS or HPP kindreds identified numerous mutations in erythrocyte membrane α-spectrin (SPTA1). Twenty-eight mutations were novel, with null alleles frequently found in trans to missense mutations. No mutations were identified in a third of SPTA1 alleles (17/48). Whole genome sequencing revealed linkage disequilibrium between the common rHS-linked α-spectrinBug Hill polymorphism and a rare intron 30 variant in all 17 mutation-negative alleles. In vitro minigene studies and in vivo splicing analyses revealed the intron 30 variant changes a weak alternate branch point (BP) to a strong BP. This change leads to increased utilization of an alternate 3' splice acceptor site, perturbing normal α-spectrin mRNA splicing and creating an elongated mRNA transcript. In vivo mRNA stability studies revealed the newly created termination codon in the elongated transcript activates nonsense mediated decay leading to spectrin deficiency. These results demonstrate a unique mechanism of human genetic disease contributes to the etiology of a third of cases of rHS, facilitating diagnosis and treatment of severe anemia, and identifying a new target for therapeutic manipulation.

Successful treatment of an infant with constitutional chromosomal abnormality and hemangiopericytoma with chemotherapy alone.

Hemangiopericytoma is a rare vascular tumor, of which 5% to 10% occur in the pediatric population. Although usually benign in infants, local recurrence, metastasis, and deaths have been reported. Clonal chromosomal rearrangements have been described, most involving the long arm of chromosome 12. We report a case of a 6-month-old boy with an hemangiopericytoma of the left forearm initially incorrectly diagnosed as hemangioma. He was treated successfully with chemotherapy alone using vincristine, doxorubicin, actinomycin-D, and cyclophosphamide. Although cytogenetic analysis was not performed on his biopsy, it was later discovered that a prenatal karyotype had shown 46,XY,inv(12)(q15q24.1).

Flow cytometric diagnosis of X-linked hyper-IgM syndrome: application of an accurate and convenient procedure.

Hyper-IgM (HIM) syndrome encompasses a family of congenital immunodeficiency states characterized by frequent infections and markedly low serum levels of IgG, IgA, and IgE but normal or elevated levels of IgM. Many patients have neutropenia. The major defect shared by all forms of HIM syndrome is a failure of immunoglobulin isotype-switching. Recently, a flow cytometric assay was described in the immunology literature for diagnosis of patients with inherited X-linked (X-HIM) syndrome. Using this assay, activated CD4 peripheral blood T lymphocytes from two patients suspected of having HIM syndrome, and from their mothers, were subjected to immunofluorescent flow cytometric analysis for the expression of CD40 ligand (CD154 antigen). Test results established the diagnosis of X-HIM syndrome that was inherited in one patient and spontaneous in the other. The authors' experience illustrates that the flow cytometric assay used and described in detail here can facilitate an accurate and timely diagnosis of X-HIM syndrome. Because the assay can be carried out in most clinical flow cytometry facilities, it lends itself to use by pediatric hematologists in the standard evaluation of patients whose differential diagnosis includes that disorder. The authors hope this report will raise awareness of the value of this procedure.