Germline 3p22.1 microdeletion encompassing RPSA gene is an ultra-rare cause of isolated asplenia

Background Isolated Congenital Asplenia (ICA, OMIM #271400) is a rare, life-threatening abnormality causing immunodeficiency, which is characterized by the absence of a spleen. Diagnosis should be completed in early childhood and antibiotic prophylaxis applied with additional vaccinations. Case presentation We report the case of a six-month old girl with hematologic abnormalities and asplenia documented in imaging, with Howell-Jolly bodies in peripheral blood smear. Targeted Next Generation Sequencing screening did not reveal any pathogenic variant in genes associated with congenital asplenia. Since absence of the spleen was found by imaging, high-resolution copy number variations detection was also performed using genomic Single Nucleotide Polymorphism microarray: a heterozygous 337.2 kb deletion encompassing the RPSA gene was observed, together with SLC25A38, SNORA6, SNORA62 and MOBP genes. Despite haploinsufficiency of SLC25A38, SNORA6, SNORA62 and MOBP, no change in the clinical picture was observed. A search of available CNV databases found that a deletion of the RPSA locus seems to be unique and only duplications were found in this region with the frequency of less than 0.02%. Conclusions Copy number variations in RPSA gene locus are ultrarare cause of isolated asplenia. Furthermore, since the patient does not present any concomitant clinical features, it would appear that haploinsufficiency of SLC25A38, SNORA6, SNORA62 and MOBP genes does not affect the phenotype of patients. However, to confirm this thesis a longer follow-up of the patient’s development is needed.

Isolated Congenital Asplenia in an Asymptomatic Patient: A Very Rare Diagnosis

Isolated congenital asplenia is a rare condition that mostly manifests in the early years, usually due to fatal systemic infections. In this paper, however, we present a case of a 36-year-old asymptomatic patient who was referred for suspected hyposplenism, with no history of splenectomy. There were no significant changes on physical examination. Blood analysis revealed leukocytosis and thrombocytosis as well as moderate anisopoikilocytosis and red blood cells with Howell–Jolly bodies. No spleen or other malformations were identified on imaging. Individuals with isolated congenital asplenia have an increased susceptibility to invasive infections and sepsis, with rapid clinical decline and a high mortality rate despite treatment.

Ultrastructural and morphometric analysis of enlarged platelets in congenital isolated asplenia

Introduction. Congenital asplenia is an extremely rare condition that can be separate entity due to a specific defect of spleen development or may occur in the context of a malformation syndrome. The patients with asplenia have thrombocytosis and susceptibility to life-threatening infections. Case report. We report a 52-years-old female patient with isolated congenital asplenia with pseudothrombocytopenia and giant platelets. Estimation of platelets life with radioactive indium showed normal lenght of platelets life (9 days). Flow cytometric analysis of platelets showed normal expression of CD41 and CD42b antigens. The mean platelet diameter of asplenic patient measured on the ultrathin sections by the transmission electron microscope was significantly higher than in the healthy individuals (3.81 ? 1.16 ?m vs. 2.37 ? 0.61 ?m, p < 0.05). There were very few platelets of diameter more than 4 ?m found in healthy individuals (around 1%) in comparison to > 40% of the patient?s platelets. The ultrastructural studies revealed normal morphology of megakaryocytes. The platelets were uniformly spheroid in shape with conspicuous pseudopodia and the centralization of granules. There were no marginal bands of microtubules inside the platelets. Conclusion. The first case of congenital asplenia with the pseudothrombocytopenia and giant platelets is presented. We discussed the pathogenesis of giant platelets and possible relation of observed ultrastructural changes of platelets with the severe three-vessel coronary artery disease in our patient.

Incomplete penetrance for isolated congenital asplenia in humans with mutations in translated and untranslated RPSA exons

Isolated congenital asplenia (ICA) is the only known human developmental defect exclusively affecting a lymphoid organ. In 2013, we showed that private deleterious mutations in the protein-coding region of RPSA, encoding ribosomal protein SA, caused ICA by haploinsufficiency with complete penetrance. We reported seven heterozygous protein-coding mutations in 8 of the 23 kindreds studied, including 6 of the 8 multiplex kindreds. We have since enrolled 33 new kindreds, 5 of which are multiplex. We describe here 11 new heterozygous ICA-causing RPSA protein-coding mutations, and the first two mutations in the 5′-UTR of this gene, which disrupt mRNA splicing. Overall, 40 of the 73 ICA patients (55%) and 23 of the 56 kindreds (41%) carry mutations located in translated or untranslated exons of RPSA. Eleven of the 43 kindreds affected by sporadic disease (26%) carry RPSA mutations, whereas 12 of the 13 multiplex kindreds (92%) carry RPSA mutations. We also report that 6 of 18 (33%) protein-coding mutations and the two (100%) 5′-UTR mutations display incomplete penetrance. Three mutations were identified in two independent kindreds, due to a hotspot or a founder effect. Finally, RPSA ICA-causing mutations were demonstrated to be de novo in 7 of the 23 probands. Mutations in RPSA exons can affect the translated or untranslated regions and can underlie ICA with complete or incomplete penetrance.

Incomplete penetrance for isolated congenital asplenia in humans with mutations in translated and untranslated RPSA exons

Isolated congenital asplenia (ICA) is the only known human developmental defect exclusively affecting a lymphoid organ. In 2013, we showed that private deleterious mutations in the protein-coding region of RPSA, encoding ribosomal protein SA, caused ICA by haploinsufficiency with complete penetrance. We reported seven heterozygous protein-coding mutations in 8 of the 23 kindreds studied, including 6 of the 8 multiplex kindreds. We have since enrolled 33 new kindreds, 5 of which are multiplex. We describe here eleven new heterozygous ICA-causing RPSA protein-coding mutations, and the first two mutations in the 5’-UTR of this gene, which disrupt mRNA splicing. Overall, 40 of the 73 ICA patients (55%) and 23 of the 56 kindreds (41%) carry mutations located in translated or untranslated exons of RPSA. Eleven of the 43 kindreds affected by sporadic disease (26%) carry RPSA mutations, whereas 12 of the 13 multiplex kindreds (92%) carry RPSA mutations. We also report that six of eighteen (33%) protein-coding mutations and the two (100%) 5’-UTR mutations display incomplete penetrance. Three mutations were identified in 2 independent kindreds, due to a hotspot or a founder effect. Lastly, RPSA ICA-causing mutations were demonstrated to be de novo in 7 of the 23 probands. Mutations in RPSA exons can affect the translated or untranslated regions and can underlie ICA with complete or incomplete penetrance.