Myopathy, Congenital, With Fiber-Type Disproportion, X-Linked

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Retrieved

2019-09-22

Source

Omim

Trials

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Genes

SELENON, ACTA1, TPM3, TPM2, LMNA, MAP3K20, ITGA7, RYR1, MYH7, ORAI1, MTM1, MYL2, DNM2, STIM1, MTMR14, BIN1, HACD1, CCDC78, FKRP, B4GAT1, POMGNT1, CHKB, POMT1, LARGE1, FKTN, ACTB, TMCO1, DMPK, CD38, MYH7B

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For a general phenotypic description of congenital fiber-type disproportion, see CFTD (255310).

Clinical Features

Clarke et al. (2005) reported a 4-generation Australian family in which at least 7 males had marked congenital muscle weakness inherited in an X-linked pattern. All presented at birth with bilateral ptosis, facial weakness, poor suck, weak cry, generalized hypotonia, and respiratory insufficiency. Six infants died of respiratory failure between the 6 and 14 weeks of age; only 1 survived to age 5.5 years at the time of the report. The survivor had facial weakness and mild generalized limb weakness, but could walk fast, jump, and did not demonstrate Gowers sign. He also showed dilated cardiomyopathy. Serum creatine kinase and lactate were normal. Muscle biopsy showed fiber-type disproportion with type 1 fibers at least 12% smaller than type 2 fibers. Obligate female carriers showed mild muscle weakness and facial weakness, particularly of the frontalis muscle.

Mapping

By linkage analysis of an Australian family with X-linked congenital myopathy with fiber-type disproportion, Clarke et al. (2005) identified a candidate disease locus between Xq13.1-q22.1 (maximum parametric lod score of 3.25), defined by markers DXS8019 and DXS993 and spanning 18 cM. Sequencing excluded mutations in the SMPX (300226), ITGB1BP2 (300332), PDHA1 (300502), PDK3 (300906), and AFX1 (300033) genes.