Page 66 - 2019_08-Haematologica-web

V. Picard et al.
continued from the previous page
Mutation in Predicted mutation effect scores
VariantdbSNP NM_001142864.2 Exon Aminoacid Frequency Cons PolyPhen-2 SIFT MT Predicted n Reported
GnomAD %
0
0
0
0.53
0
0
0
0
0
0.016
0.00066
0
0.029
0
0.68
nt HumVar AA
+ 0.983
+ Pr D
+ 0.754 0.06
+ Po T
+ 0.826 0.01 + Po D
+/- 0.873 0.07
+/- Po T
+ 0.437 0.21 +/- B T
+ 0.811 0.01
+/- Po D
+/- 0.998 0 + Pr D
+/- 0.557 0.25
+/- Po T
+ 0.394 0.07 +/- B T
+ 0.973 0.04
+/- Pr D
+ 0.978 0 + Pr D
score value pathogenicity
family (subject)§
145 (1)
153 (1)
128 (2)
family (subject) ref
-
-
-
-
-
-
2 (8) 19
*23
-
-
1(1) 11, 18
-
-
8(14) 10
-
None c.6479C>T
None c.6574C>A
None c.6601G>T
45
45
45
47
47
50
51
51
51
51
51
51
51
51
51
p.Pro2160Leu
p. Leu2192Ile
p.Val2201Phe
p.Leu2277Met
p.Gln2308Glu
p.Gly2433Arg
p.Arg2456His
p.Phe2458Leu
p.His2464Pro
p.Val2474Met
p.Arg2488Gln
p.Glu2489Asp
p.Arg2491Trp
p.L2495_E2496
dup p.Pro2510Leu
0 1 PP DC
1 us
DC
1 PP DC
rs563555492
None
None
rs587776988
rs202127176
None
rs200243384
rs749288233
None
rs201746476
rs587776992
rs61745086
c.6829C>A
(2) c.6922C>G
c.7297G>C
(9) c.7367G>A
c.7374C>G*
(5) c.7391A>C
c.7420G>A
(10)
c.7463G>A (3, 7)
c.7467G>C
c.7471C>T (8)
c.7479_7484dup
(10) c.7529C>T
(1,9)
0.676
DC
0.994 DC
1
DC
1 DC
1
DC
1 DC
1
DC
1 DC
US 155 (3)
US 149 (1)
PP 17 (1)
Y 61,4,12,33,40,56 (15)
US 134 (1)
US 126 (2)
US 122 (1)
Y 311.31.57 (6)
PP 146(3)
US 124 (1)
Y 105.15.16.22.25
29.36.44.50.51 (20) US 27.32 (2)
+/- 0.995 0 1
+ Pr D
DC
+/- 0.892 0.02
- Pr D PM
nd nd
+ 0.991
1
nd nd
01
+ Pr D DC
Cons: phylogenetic conservation of nucleotide (nt) and amino acids (AA) according to Alamut software v2.10.0 (-- not conserved, - weakly conserved, +/- moderately conserved, + highly con- served). Predicted mutation effect scores from Polyphen-2 v2.2.6 (B: benign, Po: possibly damaging, Pr: probably damaging), SIFT v6.2.0 (T: tolerated, D: deleterious when score <0.05) and Mutation Taster v2013 (PM: polymorphism, DC: disease causing) algorithms. Pathogenicity: Y pathogenic as described in previous reports; PP scored probably pathogenic: mutation identified in a family with typical dehydrated ektacytometry, absent in population databases, affecting a moderately or highly conserved amino acid and predicted as pathogenic by at least two algorithms, PM poly- morphism: sequence variation known in population databases and amino acid weakly or not conserved and predicted as tolerated by at least two algorithms, US: unknown significance if not pathogenic, probably pathogenic or polymorphism. §: the data shown for each mutation are: total number of families, identification of each family according to Online Supplementary Table S2 (in superscript), and the total number of patients (in brackets). NB: c.6329G>A was homozygous (hmz). *Both sequence variations present on the same allele were described in a parent of a child with PIEZO1-linked lymphedema23 **This mutation was described in an apparently unrelated family10
already reported and three new families, carried the recur- rent c.1055G>A KCNN4 mutation leading to the p.Arg352His Gardos channel substitution.15 The last fami- ly included three members with marked anemia and splenomegaly; all three carried a novel KCNN4 28 bp dele- tion (c.1109_1119+17del). This deletion encompassed the exon-intron 7 junction and its consequences are not known so far, although the use of an alternate splice site can be hypothesized.
Hematologic features at diagnosis
The mean hemoglobin level of the whole cohort was 131±20 g/L (n=115). Most subjects with HX (68%) were not anemic at diagnosis and presented with compensated hemolysis. No patient was transfusion-dependent on a regular basis; occasional transfusions were necessary for
eight patients. Analysis of red cell indices indicated a trend towards macrocytosis (MCV 97±8 fL) and a high reticulo- cyte count (294±102x109/L). The mean corpuscular hemo- globin concentration was 351±13 g/L, with 38% of the patients having a level above 360 g/L (Figure 2A). After exclusion of neonates, 29 patients out of 97 from 20 fam- ilies (30%) had a hemoglobin level below 120 g/L, includ- ing 8/12 KCNN4-mutation carriers. Interestingly, seven adults presented at diagnosis with a hemoglobin level above 160 g/L, including two who were referred for “poly- cythemia” (hemoglobin level of 181 g/L and 175 g/L), with hemolytic features. All these patients carried a PIEZO1 mutation (Figure 2B).
Regarding neonatal and childhood hematologic fea- tures, 19 cases were diagnosed before the age of 1 year (including 11 probands). Focusing on 15 cases with suffi-
1558
haematologica | 2019; 104(8)