Background
Materials and methods
Patients
Mutation analysis of the MAN2B1 gene
Collection of clinical and biochemical data
Biochemical assessments
Oligosaccharides
CSF-biomarkers of neurodegeneration
Alpha-mannosidase activity
Clinical assessments
Cognitive function test
Pulmonary function test
Motor function assessments
Audiometry
Statistical analysis
Sample size calculations
Results
Mutation spectrum and functional analyses of novel missense variants
cDNA label | Location | Predicted effect on protein | Activity2
| Processing3
| Location4
|
---|---|---|---|---|---|
Nonsense mutations/duplications/deletions
| |||||
c.383G>A | Exon 3 | p.(Trp128Ter) | |||
c.809dupA | Exon 6 | p.(Asp270GlufsTer54) | |||
c.812_813dupTG | Exon 6 | p.(Leu272CysfsTer27) | |||
c.1047_1048dupCC | Exon 8 | p.(His350ProfsTer15) | |||
c.2675dupT | Exon 22 | p.(Arg893AlafsTer38) | |||
c.2944_2947delCCGT | Exon 24 | p.(Pro982ThrfsTer50) | |||
Splice site mutations
| |||||
c.1230 + 5G>A1
| Intron 9 | p.? | |||
c.2436 + 5G>A | Intron 20 | p.Glu786_Met812del | |||
Missense mutations
| |||||
c.304G>A | Exon 3 | p.(Asp102Asn) | No | Yes | Lysosomal |
c.458G>T | Exon 4 | p.(Gly153Val) | No | Yes | Lysosomal |
c.2885G>A5
| Exon 22 | p.(Arg962His) | Yes | Yes | Lysosomal |
Allele 1 | Allele 2 | Localisation | Genotype group10/subcellular localisation subgroups | |||
---|---|---|---|---|---|---|
Family number | Label cDNA | Label Protein | Label cDNA | Label Protein | ||
1A1
| c.164G>T | p.(Cys55Phe) | c.599A>T | p.(His200Leu) | Exon 2 / Exon 4 | 3 |
1B1
| c.164G>T | p.(Cys55Phe) | c.599A>T | p.(His200Leu) | Exon 2 / Exon 4 | 3 |
2 | c.231G>A | p.(Trp77Ter) | c.2398G>C | p.(Gly800Arg) | Exon 2 / Exon 20 | 2* |
3 | c.283G>C | p.(Ala95Pro) | c.283G>C | p(.Ala95Pro) | Exon 3 / Exon 3 | 2 |
4 | c.283G>C | p.(Ala95Pro) | c.283G>C | p.(Ala95Pro) | Exon 3 / Exon 3 | 2 |
5 | c.304G>A | p.(Asp102Asn) | c.2885G>A | p.(Arg962His) | Exon 3 / Exon 23 | 3 |
6 | c. 338_348dup11 | p.(Ile117ProfsTer44) | c. 338_348dup11 | p.(Ile117ProfsTer44) | Exon 3 / Exon 3 | 1 |
7 | c.383G>A | p.(Trp128Ter) | c.383G>A | p.(Trp128Ter) | Exon 3 / Exon 3 | 1* |
8 | c.418C>T | p.(Arg140Ter) | c.418C>T | p.(Arg140Ter) | Exon 3 / Exon 3 | 1 |
9A2
| c.458G>T | p.(Gly153Val) | c.[1230+5G>A;c.2248C>T] | p.[?; Arg750Trp] | Exon 4 / Intron 9 | 3 |
9B2
| c.458G>T | p.(Gly153Va) l | c.[1230+5G>A; c.2248C>T] 11
| p.[?; Arg750Trp] | Exon 4 / Intron 9 | 3 |
10 | c.590C>G | p.(Pro197Arg) | c.2724G>A | p.(Trp908Ter) | Exon 4 / Exon 22 | 2* |
11 | c.598C>A | p.(His200Asn) | c.1548delT | p.(Leu518TrpfsTer5) | Exon 4 / Exon 13 | 3* |
12 | c.685C>T | p.(Arg229Trp) | c.2439_2444dup6 | p.(His814_Arg815dup) | Exon 5 / Exon 21 | 3* |
13 | c.783C>A | p.(Tyr261Ter) | c.783C>A | p.(Tyr261Ter) | Exon 6 / Exon 6 | 1 |
14 | c.788C>T | p.Pro263Leu | c.2355G>A | p.(Arg757MetfsTer6) | Exon 6 / Exon 19 | 3 |
15 | c.809dupA | p.(Asp270GlufsTer54) | c.2675dupT | p.(Arg893AlafsTer38) | Exon 6 / Exon 22 | 1 |
16 | c.812_813dupTG | p.(Leu272CysfsTer27) | c.812_813dupTG | p.(Leu272CysfsTer27) | Exon 6 / Exon 6 | 1 |
17 | c.909+731del6272 | p.Gly304del245 | c.953C>T | p.Ser318Leu | Intron 6-13 / Exon 7 | 3 |
18 | c.1026+2 T>G | p.[Val339_Ala341del; p.Val339_Gln342del] | c.1830+1G>C | p.Val549_Glu610del | Intron 7 / Intron 14 | 2 |
19 | c.1047_1048dupCC | p.(His350ProfsTer15) | c.2248C>T | p.Arg750Trp | Exon 8 / Exon 18 | 2 |
20A3
| c.1055 T>C | p.(Leu352Pro) | c.1055 T>C | p.(Leu352Pro) | Exon 8 / Exon 8 | 2 |
20B3
| c.1055 T>C | p.(Leu352Pro) | c.1055 T>C | p.(Leu352Pro) | Exon 8 / Exon 8 | 2 |
21 | c.1152_1153dupCC | p.(His385ProfsTer93) | c.1831-2A>G | p.His611GlyfsTer3 | Exon 9 / Intron 14 | 1 |
22 | c.1152_1153dupCC | p.(His385ProfsTer93) | c.1152_1153dupCC | p.His385ProfsTer93 | Exon 9 / Exon 9 | 1 |
23 | c.1310-2A>G | p.(?) | c.2248C>T | p.Arg750Trp | Intron 10 / Exon 18 | 2 |
24 | c.1333C>T | p.(His445Tyr) | c.1333C>T | p.(His445Tyr) | Exon 11 / Exon 11 | 2 |
25 | c.1351G>T | p.(Gly451Cys) | c.[1501 T>A; 2849G>C] 11
| p.([Cys501Ser; Arg950Pro]) | Exon 11 / Exon 12 | 3 |
26A4
| c.1358C>T | p.(Ser453Phe) | c.1358C>T | p.(Ser453Phe) | Exon 11 / Exon 11 | 2 |
26B4
| c.1358C>T | p.(Ser453Phe) | c.1358C>T | p.(Ser453Phe) | Exon 11 / Exon 11 | 2 |
27A5
| c.1370 T>A | p.(Val457Glu) | c.2248C>T | p.Arg750Trp | Exon 11 / Exon 18 | 3* |
27B5
| c.1370 T>A | p.(Val457Glu) | c.2248C>T | p.Arg750Trp | Exon 11 / Exon 18 | 3* |
28A6
| c.1383C>A | p.(Tyr461Ter) | c.2402dupG | p.(Ser802GlnfsTer129) | Exon 11 / Exon 20 | 1* |
28B6
| c.1383C>A | p.(Tyr461Ter) | c.2402dupG | p.(Ser802GlnfsTer129) | Exon 11 / Exon 20 | 1* |
29 | c.1388_1389delGC | p.(Arg463ProfsTer53) | c.2426 T>C | p.Leu809Pro | Exon 11 / Exon 20 | 2* |
30 | c.1527+1G>C | p.(?) | c.1527+1G>C | p.(?) | Intron 12 / Intron 12 | 1* |
31A7
| c.1816delA | p.Thr606ProfsTer18 | c.1830+1G>C | p.Val549_Glu610del | Exon 14 / Intron 14 | 1 |
31B7
| c.1816delA | p.Thr606ProfsTer18 | c.1830+1G>C | p.Val549_Glu610del | Exon 14 / Intron 14 | 1 |
32 | c.1830+1G>A | p.(?) | c.2248C>T | p.Arg750Trp | Intron 14 / Exon 18 | 2 |
33 | c.1830+1G>C | p.Val549_Glu610del | c.1830+1G>C | p.Val549_Glu610del | Intron 14 / Intron 14 | 1 |
34 | c.1830+1G>C | p.Val549_Glu610del | c.2248C>T | p.Arg750Trp | Intron 14 / Exon 18 | 2 |
35 | c.1830+1G>C | p.Val549_Glu610del | c.2426 T>C | p.Leu809Pro | Intron 14 / Exon 20 | 2 |
36 | c.1830+1G>C | p.Val549_Glu610del | c.2248C>T | p.Arg750Trp | Intron 14 / Exon 18 | 2 |
37A8
| c.1831-2A>G | p.His611GlyfsTer3 | c.1831-2A>G | p.His611GlyfsTer3 | Intron 14 / Intron 14 | 1 |
37B8
| c.1831-2A>G | p.His611GlyfsTer3 | c.1831-2A>G | p.His611GlyfsTer3 | Intron 14 / Intron 14 | 1 |
38 | c.2234C>G | p.(Thr745Arg) | c.2234C>G | p.Thr745Arg | Exon 18 / Exon 18 | 3 |
39A9
| c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
39B9
| c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
40 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
41 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
42 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
43 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
44 | c.2248C>T | p.Arg750Trp | c.2299C>T | p.Gln767Ter | Exon 18 / Exon 19 | 2* |
45 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2 |
46 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2* |
47 | c.2248C>T | p.Arg750Trp | c.2426 T>C | p.Leu809Pro | Exon 18 / Exon 20 | 2* |
48 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2 |
49 | c.2248C>T | p.Arg750Trp | c.2426 T>C | p.Leu809Pro | Exon 18 / Exon 20 | 2 |
50 | c.2248C>T | p.Arg750Trp | c.2251G>T | p.(Glu751Ter) | Exon 18 / Exon 20 | 2* |
51 | c.2248C>T | p.Arg750Trp | c.2248C>T | p.Arg750Trp | Exon 18 / Exon 18 | 2 |
52 | c.2355G>A | p.Arg757MetfsTer6 | c.2355G>A | p.(Arg757MetfsTer6) | Exon 19 / Exon 19 | 1 |
53 | c.2398G>T | p.(Gly800Trp) | c.2944_2947delCCGT | p.(Pro982ThrfsTer50) | Exon 20 / Exon 24 | 2 |
54 | c.2436+5G>A | p.Glu786_Met812del | c.2887delG | p.(Glu963ArgfsTer70) | Intron 20 / Exon 23 | 1 |
55 | c.2724G>A | p.(Trp908Ter) | c.2724G>A | p.(Trp908Ter) | Exon 22 / Exon 22 | 1 |
56 | c.2920dupA | p.(Thr974AsnfsTer81) | c.2920dupA | p.(Thr974AsnfsTer81) | Exon 23 / Exon 23 | 1* |
57 | c.2921_2922delCA | p.(Thr974ArgfsTer80) | c.2921_2922delCA | p.(Thr974ArgfsTer80) | Exon 23 / Exon 23 | 1 |
Genotype-phenotype correlations
Genotype/subcellular localisation subgroups | N | Age +/-SD, Mean (years) | Age Median (years) | Age Minimum (years) | Age Maximum (years) |
---|---|---|---|---|---|
Subgroup 1 | 21 | 22.9 ± 11.6 | 23.0 | 5.7 | 42.1 |
Two null-mutations (nonsense, frameshift, large truncation) | |||||
Subgroup 2 | 32 | 17.9 ± 7.6 | 17.9 | 6.0 | 35.0 |
Missense/in-frame dup/del localised to the ER | |||||
Subgroup 3 | 13 | 17.4 ± 7.8 | 17.3 | 5.4 | 29.0 |
Missense/in-frame dup/del localised to the lysosomes | |||||
Total | 66 | 19.4 ± 9.3 | 17.3 | 5.4 | 42.1 |
Analysis/clinical test | N | Subgr. 1, mean | Subgr. 2, mean | Subgr. 3, mean | Min. | Max. | Total, mean | SD | p-value Pairwise comparison* |
---|---|---|---|---|---|---|---|---|---|
CSF-oligo (μmol/L) | 35/35 | 11.5 ± 2.3 | 11.9 ± 3.2 | 7.1 ± 2.0 | 4.0 | 19 | 10.7 | 3.4 | H0 3 = 2: p = 0.001, H0 3 = 1: p = 0.011 |
H0 2 = 1: p = 1.000 | |||||||||
Cognitive test (VR battery) (years) | 35/35 | 5.8 ± 1.7 | 5.3 ± 1.5 | 7.0 ± 0.9 | 3.0 | 9.0 | 5.8 | 1.6 | H0 3 = 2: p = 0.049, H0 3 = 1: p = 0.344, |
H0 2 = 1: p = 1.000 | |||||||||
Cognitive test (Memory Screening) (y) | 26/26 | 6.9 ± 1.9 | 5.4 ± 2.0 | 8.8 ± 1.2 | 2.3 | 10.2 | 6.5 | 2.3 | H0 3 = 2: p = 0.02, H0 3 = 1: p = 0.215, |
H0 2 = 1: p = 0.836 | |||||||||
FVC% (%) | 54/66* | 62.3 ± 20.7 | 77.5 ± 19 % | 90.7 ± 22.7 | 30 | 140 | 75.2 | 22.7 | H0 3 = 2: p = 0.296, H0 3 = 1: p = 0.003, |
H0 2 = 1: p = 0.042 | |||||||||
BOT-2 (Coor.) (points) | 35/35 | 16.3 ± 10.1 | 11.3 ± 10.8 | 22.5 ± 7.6 | 1 | 33 | 15 | 10.8 | H0 3 = 2:p = 0.047, H0 3 = 1: p = 0.713 |
H0 2 = 1: p = 0.773 | |||||||||
BOT-2 (Balance) (points) | 35/35 | 7.6 ± 6.2 | 8.4 ± 6.1 | 14.8 ± 7.9 | 1 | 26 | 9.7 | 7.0 | H0 3 = 2: p = 0.033, H0 3 = 1: p = 0.06, |
H0 2 = 1:p = 1.00 |