P.15.11

Megaconial congenital muscular dystrophy in two children with mutations in

the CHKB Gene

A. Nascimento 1, C. Jou 2, C. Ortez 1, Y.K. Hayashi 3, I. Nishino 3,

M. Olive 4, I. Ferrer 4, J. Colomer 5, S. Paco 5, C. Jimenez-Mallebrera 5

1 Hospital Sant Joan de Deu — UB, Unitat Patologia Neuromuscular. S.

Neurologıa, Barcelona, Spain; 2 Hospital Sant Joan de Deu – UB, Servei d’

Anatomia Patologica, Barcelona, Spain; 3 National Center Of Neurology

and Pshychiatry (NCNP), Neuromuscular Research, Tokyo, Japan; 4 IDI-

BELL – Hospital Universitari de Bellvitge, Institute of Neuropathology,

Barcelona, Spain; 5 Hospital Sant Joan de Deu – UB, Unitat Patologia

Neuromuscular, Barcelona, Spain

Congenital Muscular Dystrophy (CMD) is a clinically and genetically

heterogenous group of muscle disorders. Mutations in the gene encoding

the beta subunit of choline kinase (CHKB) are associated with a recently

described form of CMD characterised by the presence of large and abnor-

mal mitochondria in muscle fibres. Choline kinase is a key enzyme in the

synthesis of phosphatidyl choline and phosphatidylethanolamine, two

phospholipids that are essential components of biological membranes.

We present two children, 9 and 5 years old, with congenital hypotonia,

joint hyperlaxity,proximal weakness and cognitive impairment without

microcephaly or brain structural changes. Autonomous ambulation

started at 2 and 3 years respectively Both patients showed mildly elevated

creatine kinase levels (250–400 UI/L).

Muscle pathology of both patients was similar showing dystrophic

changes, oxidative enzymes staining defects and very large mitochondria

distributed at the periphery of the fibre. Electron microscopy performed

in one patient confirmed the presence of large mitochondrial with structur-

ally abnormal cristae and inclusions. One patient was homozygous for a

frameshift mutation (p.Gln198fs, exon 5) whereas the other patient was

heterozygous for a mutation in intron 3 (c.447 + 2t > c) and a missense

mutation in exon 9 (p.Arg344Gln). These mutations have not been

reported before.

This form of CMD must be taken into account in the differential diag-

nosis of children presenting in the first year of life with muscle weakness,

elevated creatine kinase levels and mental retardation and with a charac-

teristic muscle biopsy which shows dystrophic changes in combination

with mitochondrial abnormalities.

http://dx.doi:10.1016/j.nmd.2013.06.636

P.15.12

Tubular aggregate myopathy caused by a heterozygous missense mutation in

STIM1

A. Oldfors 1, C. Hedberg 1, B. Lindvall 2, M. Tulinius 3

1 University of Gothenburg, Department of Pathology, Gothenburg, Swe-

den; 2 University of Orebro, Department of Neurology, Orebro, Swe-

den; 3 University of Gothenburg, Department of Pediatrics, Gothenburg,

Sweden

This woman, now 33 years old, was first investigated at age 14 and pre-

viously described as a case report of tubular aggregate myopathy (Tulinius

MH, Lundberg A, Oldfors A. Early-onset myopathy with tubular aggre-

gates. Pediatric Neurol 1996;15:68–71). There was no family history of

neuromuscular disease. Early motor milestones were normal. She never

learned to run and at four years the parents noted she had a wide-based

gait. At 12 years she lost the ability to rise from the squatting position

without using her hands. The muscle weakness was slowly progressive

over the years and she now presents with moderate proximal muscle weak-

ness and wasting of both upper and lower extremities. She has slight ptosis

and slight dysarthria but no ophthalmoplegia. CK has been constantly ele-

vated 7–40 times upper normal levels.

Muscle biopsy at age 14 and 30 years showed type 1 fiber predomi-

nance and numerous fibers (40–90% of all fibers), both type 1 and type

2, with tubular aggregates mainly located in the centre of the fibers and

widely dispersed between myofibrils. Occasional necrotic fibers were

present.

Mutation analysis of STIM1 (stromal interaction molecule 1, the main

Ca2 + sensor of the endoplasmic reticulum) revealed that the patient was

heterozygous for a dominant missense mutation c.326A > G, p.

p.His109Arg. This mutation was previously reported in two siblings in

the original recent report describing mutations in STIM1 associated with

tubular aggregate myopathy (Bohm J, Chevessier F, Maues De Paula A,

et al. Constitutive activation of the calcium sensor STIM1 causes tubu-

lar-aggregate myopathy. Am J Hum Genet 2013;92:271–8).

http://dx.doi:10.1016/j.nmd.2013.06.637

FACIOSCAPULOHUMERAL AND OCULOPHARYNGEAL MUS-

CULAR DYSTROPHIES

P.16.1

DUX 4 regulates expression of the Pro-Apoptotic Gene, p63

J.S. Domire 1, L.M. Wallace 2, S. Guckes 2, J. Liu 2, S.Q. Harper 3

1 The Ohio State University, Biomedical Sciences Graduate Program,

Columbus, United States; 2 The Research Institute at Nationwide Children’s

Hospital, Center for Gene Therapy, Columbus, United States; 3 The Ohio

State University and The Research Institute at Nationwide Children’s

Hospital, Dept. of Peds and Center for Gene Therapy, Columbus, United

States

Facioscapulohumeral muscular dystrophy (FSHD) is a dominant dis-

order that most commonly affects specific muscles of the face, shoulder gir-

dle, and limbs. The molecular mechanisms underlying FSHD have

recently emerged after several decades of study. Briefly, FSHD is associ-

ated with mis-expression of the DUX4 gene, which encodes a transcription

factor that is toxic to mammalian muscle. We hypothesized that DUX4

may contribute to FSHD pathologies by initiating downstream gene

expression changes that are incompatible with normal muscle

homeostasis.

In this study, our objective was to characterize prospective DUX4-con-

trolled pathways with the goals of further defining the pathogenic events

involved in FSHD, and potentially identifying therapeutic targets.

Through expression profiling of DUX4-expressing mouse muscles, we

found upregulation of several pro-apoptotic genes in the p53 pathway,

suggesting that DUX4 myotoxicity may involve activation of p53-depen-

dent programmed cell death. We are pursuing several p53-pathway candi-

dates, but in this study we focused on one gene: the p53 homolog p63.

Using multiple approaches, we found that DUX4 directly bound to both

mouse and human p63 promoters and preferentially transactivated the

cytotoxic isoform of p63 from each. Moreover, we showed that p63 co-

localized with DUX4 in myofiber nuclei of DUX4-overexpressing mouse

muscle and was elevated in primary muscle cells from FSHD patients com-

pared to normal controls. Importantly, p63 inhibition mitigated the pro-

apoptotic activity of over-expressed DUX4 in vitro and we are now con-

firming this genetically by investigating the effects of DUX4 expression in

muscle-specific p63 knockout mice. Together, our results suggest that p63

is a downstream target of DUX4 and may play an important role in

DUX4-mediated cell death. FSHD therapies may therefore involve dis-

rupting the DUX4-p63 axis in FSHD-affected muscles.

http://dx.doi:10.1016/j.nmd.2013.06.638

822 Abstracts / Neuromuscular Disorders 23 (2013) 738–852