Clinical features of Demyelinating Charcot-Marie-Tooth disease Davide Pareyson “C.Besta” National Neurological Institute Milan, Italy Prague May 25, 2004

CMT network in Italy Clinical studies of demyelinating CMT –Role of gender and pregnancy in CMT1A –Involvement of CNS in CMTX –Examples of mutations in new genes Current studies Future therapies?

Demyelinating CMT Autosomal dominant CMT1APMP22 duplication (17p11.2)60-90% PMP22 point mutation 1-3 % CMT1BMPZ (P0) 4-5% CMT1C LITAF/SIMPLErare CMT1DEGR2++ rare X-linked CMTXGJ1/Cx327-10% of all CMT

Demyelinating CMT Autosomal recessive CMT4AGDAP1 CMT4B1MTMR2 CMT4B2MTMR13 CMT4C KIAA1985 CMT4D (DSD)PERIAXIN (PRX) HMSN-LNDRG1

CMT1A (PMP22 duplication) MOST FREQUENT CMT SUBTYPE (40-50%) CLINICAL PHENOTYPE –relatively mild, although variable NERVE CONDUCTION: mostly MCV m/s –diffuse & uniform slowing, no conduction block NEUROPATHOLOGY –diffuse onion bulbs, –de-remyelination MODIFIER FACTORS?

Progesterone and derivates increase PMP22 expression

Animal model of CMT1A: worsening with progesterone, improvement with its antagonist onapristone (Sereda, 2003)

EFFECTS OF PROGESTERONE ON CMT1A? Progesterone and derivates increases PMP22 expression Animal model of CMT1A: worsening with progesterone, improvement with its antagonist onapristone (Sereda, 2003) Reported cases of CMT worsening during pregnancy (dramatic increase in progesterone levels)

Is there an effect of gender and pregnancy on CMT1A severity? Retrospective evaluation of 84 CMT1A pts. Clinical and electrophysiologic data: –Rankin score; presence and severity of clinical signs –MCV, DL, CMAPs, F-lat, SCV, SAP ampl. Comparison between females and males Subgroup analysis for females in fertile age (15 to 50-yr-old) vs males same age Retrospective interview about disease course during pregnancy

Results. Clinical data Females 48, Males 36 Age at onset was similar –Females = 10.9 ± 10.8; Males = 8.3 ± 11.3 yrs. Age at evaluation higher in females –Females = 34.6 ± 16.9; Males = 26.5 ± 17.5 yrs. Overall no difference in disease severity Upper limb sensory loss F > M (p = 0.05; p < 0.03 for 15 to 50-year-old patients)

CMT1A & PREGNANCY N. pts. = 20; pregnancy = 44 4 patients had CMT worsening (gait disturbances, unsteadiness, weakness, sensory disturbances) 6 patients had minor complaints (paresthaesias, cramps, pain)

Conclusions The effect of sex hormones on PMP22 does not result in relevant difference in disease severity between the two genders. Mild differences in upper limb clinical and electrophysiologic findings might be due to median nerve involvement at the carpal tunnel. Some female patients reported worsening of symptoms during pregnancy. Disease and normal controls need to be evaluated to establish whether this is truly a CMT1A-related phenomenon.

X-linked Charcot-Marie-Tooth disease (CMTX) 2nd most common CMT variety (7-10%) Connexin-32 (GJ1/Cx32) gene mutations, Xq13.1 Hemizygous males more severely affected Isolated reports of central nervous system (CNS) involvement: –9 patients with transient CNS symptoms –few pts. abnormal examination (Babinski sign, etc) –evoked potentials and brain MRI abnormalities

Connexin-32 PNS: non-compact myelin gap-junctions in Schwann cells CNS: oligodendrocytes, some neurons. function?

CNS involvement Clinic ex. (27 pts: 13 M, 14 F, from 11 families): 2 M Babinski, 2 (1 M + 1 F) rest tremor Evoked potentials (central components): –Brainstem acoustic BAEPs18pts. –Visual Pattern-VEPs & Flash-VEPs16 “ –Somatosensory SEPs16 “ –Motor MEPs16 “ Brain MRI 14 “

Brainstem auditory evoked potential (BAEP)

ms/DV/D#Avg R1/R2 Left (Cz-A1) I II III V 20.2u5022/5213 Right (Cz-A2) I II III V 20.2u5011/3866 Left (Cz-A1) I II III V 10.5u2133/2446 Right (Cz-A2) I II III V 10.5u 2342/ D Control CMTX

BAEPs: clear abnormalities 12/18 pts (8/9 M, 4/9 F) borderline 4 pts, normal 2 pts (2 F) I-V Interpeak time (ms) NORMAL3.95  0.17 CMTX FEMALES4.30  0.43 CMTX MALES 5.48  0.9

Somatosensory and motor evoked potential (SEP, MEP) SEP stimulus N20 N13 MEP CCT registration

SEPs: N13-N20 –normal values:  7.1 msec –CMTX: Right 7.6  2.5 msec, range msec Left 7.4  2.0 msec, range 5, msec MEPs: CCT –normal values:  7.2 msec –CMTX: Right 7,1  1,5 msec, range 5,5-10 msec Left 7,2  1,8 msec, range 5,1-12 msec

Evoked potential abnormalities E.P.tot MF BAEP12/188/94/9 SEP (N13-N20) 8/165/83/8 MEP (CCT) 7/165/92/7 VEP-pattern1/161/80/8 VEP-flash9/154/75/8

CMTX NORMAL

CMTX Axial brain MRI, FLAIR sequence : mild hyperintensity in the piramidal tracts

CMTX Axial Brain MRI (A) Marked hypointensity in the periferic portion of dentate nuclei on T2 w.i. Coronal MRI (B) Small foci of hyperintensity in the hilum of the dentate nuclei on FLAIR sequence A B

CMTX Hypointensity on T2 w.i. in the postero-lateral aspect of the putamina Normal

NEURORADIOLOGY Pts.MF BRAIN MRI subtle abnormalities 936 = mild atrophy422 = mild Corticospinal tract hyperintensity 615 = hypointensity of dentate n. & putamina 202

Arg22Stop (2) Arg164Gln Arg164Leu * Val181Met Thr185Ile Arg220Stop (2) Leu9Trp

Conclusions 18/19 pts. (9/10 M, 9/9 F)Subclinical CNS involvement in: 18/19 pts. (9/10 M, 9/9 F) –BAEPs most reliable (overall 67%; males 89%) –SEPs (50%) & MEPs (44%) useful –Flash-VEPs high % abnormalities (73%) –role of MRI ? –pathophysiology? Cx32 in CNS oligodendrocytes, neuronal populations of brainstem, cortex, basal ganglia, nigra interaction with other connexins?

CNS involvement in CMT1A? Evoked potential studies (central components) E.P.N° examsabnormal BAEP202 borderline SEP (N13-N20) 120 MEP (CCT) 50 VEP-pattern50 VEP-flash 50

CMT1C Chr 16p13.3-p12 LITAF = LIPOPOLYSACCHARIDE-INDUCED TUMOR NECROSIS FACTOR-ALPHA FACTOR (SIMPLE = SMALL INTEGRAL MEMBRANE PROTEIN OF LYSOSOME/LATE ENDOSOME) LITAF may play a role in protein degradation pathways Widely expressed, including cytoplasm of Schwann cells

Severe CMT1 due to LITAF mutation (Thr49Met) Marked motor and sensory impairment, scoliosis NCV < 35 m/s absent distal CMAPs & SAPs

PERIAXIN

PRX gene on 19q code for L e S- periaxin Interaction between L-periaxin, cytoskeleton & membrane proteins like dystroglican-sarcoglican complex Necessary for PNS myelin maintainance Mutations in families with DSD & CMT4 PRX k.o. mouse develop a severe demyelinating neuropathy with allodinia e iperalgesia

Recessive CMT4/DSD due to PRX gene mutations (Glu547Stop - Pro807fs) II-8. Early onset, delayed motor milestones, severe sensory-motor impairment, scoliosis. MCV 5-9 m/s II-9. Later onset, less severe involvement. MCV m/s 5 3 II-8II-9

Ongoing studies Quality of life in CMT (funded by Telethon) Future studies Therapy? –Steroids – I.V. Immunoglobulin (IVIG) –NT3 –Progesterone antagonists –Ascorbic Acid

Franco Taroni Micaela Milani Matilde Laurà Angelo Sghirlanzoni Vidmer Scaioli Claudia Ciano Michela Morbin Isabella Moroni Alessandra Erbetta Luisa Chiapparini “C.Besta” National Neurological Institute, Milan - Italy

BAEPs: clear abnormalities 12/18 pts (8/9 M, 4/9 F) borderline 4 pts, normal 2 pts (2 F) dx (ms)sin (ms) normal I wave1,63  0,141,67  0,35 1,59 III “4,12  0,34*4,21  0,49 * 3,70 V “6,55  1,05**6,65  1,04 ** 5,54 I-III int.2,51  0,33*2,54  0,37 *2,10 III-V “2,42  0,73**2,44  0,62 ** 1,85 I-V “4,92  1,01**4,98  0,92 ** 3,95