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A retrospective series of 126 HX cases
cient data, seven had neonatal jaundice, requiring ex san- guino transfusion in one case and phototherapy in the other six. During the first month of life, anemia was more marked, 48% having a hemoglobin level below 120 g/L (Figure 2B). Five infants were transfused during their first year of life. After the age of 1 year, no patient was regular- ly transfused except one KCNN4-HX infant with severe anemia requiring in utero then post-natal transfusions, who underwent splenectomy with a partial improvement thereafter.13 These data demonstrate the more severe hematologic phenotype after birth, and the progressive improvement as the patients become older.
Focusing on hematologic parameters for each geno-
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type, KCNN4-HX cases were characterized by a lower hemoglobin level (102±13 vs. 134±19 g/L, P<0.001), retic- ulocyte count (178.1±63.1 vs. 307.5±106 x109/L, P<0.001) and mean corpuscular hemoglobin concentration (332±12.9 vs. 354±24.1 g/L, P<0.05) than PIEZO1-HX cases (Figure 2C-E). The normal mean corpuscular hemo- globin concentration as well as the non-typical ektacy- tometry profile reflected the absence of clear erythrocyte dehydration in KCNN4-HX.
In terms of red cell morphology, stomatocytes were noted on the blood smear in the majority of PIEZO1-HX (65%) samples and were considered as “few” or “rare” on semi-quantitative evaluation in 75% of them.
Figure 2. Main hematologic data and red cell indices in PIEZO1 - and KCNN4-hereditary xerocytosis. (A) Hematologic features in the whole population of patients (index cases + family members positively tested): results are shown as mean hemoglobin (Hb, g/L), mean corpuscular volume (MCV, fL), reticulocyte count (Ret, x109/L) and mean corpuscular hemo- globin concentration (MCHC, g/L). (B) Percentages of patients for each hemoglobin subgroup in the neonatal period (age <1 month, n=14, black boxes) in comparison with adults and infants after the age of 1 month (n=97, gray boxes). Forty-eight percent of neonates had a hemoglobin value under 100 g/L, while in 70% of adults and infants older than 1 month, hemo- globin level was in the normal range for the age. (C) Hemoglobin level was higher in PIEZO1-hereditary xerocytosis (HX) (n=80) than in KCNN4-HX (n=12): mean hemoglobin 134±19 g/L vs. 102±13, P<0.001. (D) Reticulocyte count in PIEZO1-HX vs. KCNN4-HX: 307.5±106 (x109/L) vs. 178.1±63.1 (x109/L), P<0.001. (E) MCHC in PIEZO1-HX vs. KCNN4-HX: 354±24.1 vs. 332 ±12.9 g/L, P<0.05. The MCHC value was obtained on an ADVIA2120 blood analyzer. (F) Frequency of typical stomatocytes on peripheral blood smear examination between PIEZO1-HX (n=63) and KCNN4-HX (n=10): +: rare, ++: few, +++: many.
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