Abstract:

Mutations in LMNA, encoding A-type lamins, lead to diverse disorders, collectively called "laminopathies," which affect the striated muscle, cardiac muscle, adipose tissue, skin, peripheral nerve, and premature aging. We describe a patient with limb-girdle muscular dystrophy type 1B (LGMD1B) carrying a heterozygous p.Arg377His mutation in LMNA, in whom skeletal muscle symptom onset was at the age of 65 years. Her weakness started at the erector spinae muscles, which showed marked pseudo-hypertrophy even at the age of 72 years. Her first episode of syncope was at 44 years; however, aberrant cardiac conduction was not
revealed until 60 years. The p.Arg377His mutation has been previously reported in several familial LMNA-associated myopathies, most of which showed muscle weakness before the 6th decade. This is the first report of pseudo-hypertrophy of paravertebral muscles in LMNA-associated myopathies. The pseudo-hypertrophy of paravertebral muscles and the elderly-onset of muscle weakness make this case unique and reportable.

日本語要旨:

A型ラミンをコードするLMNA遺伝子の変異は、ラミノパチーと呼ばれる多様な障害を起こす。今回、LMNA遺伝子にヘテロ接合のp.Arg377His変異を持つ、65歳から骨格筋症状が出現した肢帯型筋ジストロフィー1B型(LGMD1B)患者を報告する。脊柱起立筋から筋力低下が始まり、72歳時には著明な脊柱起立筋の偽性肥大を認めた。44歳から失神を認めたが、60歳まで心筋の伝導路異常は認めなかった。p.Arg377His変異は、家族性のLMNA遺伝子関連ミオパチーにおいて脊椎周囲の筋の仮性肥大を起こすことがこれまでに報告されているが、それらのほとんどは60歳までに筋力低下を示している。脊椎周囲の筋の仮性肥大がある点、筋力低下の発症が高齢であるという点で本症例は他にみられない。