Introduction:
Pathogenic mutations in the slow α-tropomyosin gene (TPM3 ) have
been associated with three distinct histological entities: nemaline
myopathy (NM, NEM1), cap disease (CD), and congenital fibre-type
disproportion (CFTD)[1]. Recently, Marttila et al. summarized the
findings in 35 clinically and histologically characterized families with
22 different TPM3 variants and found that majority of the
families(30/35) had missense mutations segregating in an autosomal
dominant fashion or arising de novo [2]. Nemaline myopathies
are heterogeneous congenital muscle disorders that cause skeletal muscle
weakness and, in some cases, death immediately after birth [3]. Mild
progressive proximal muscular weakness is the most common manifestation
of nemaline myopathy (NEM)[4]. In neonates,
NEM is rarely reported in the
literature, its diagnosis is difficult to establish and as a result,
performing a muscle biopsy is instrumental [5]. Generally, NEM
incidence is unknown, although two studies, one in Finlandestimated the
incidence to be 1 in 50,000 live births, and one in an American
Ashkenazi Jewish population estimated an incidence of 1/500, suggesting
a genetic founder effect [6].It accounts for approximately 20 % of
cases of all congenital myopathies [6].
We report herein a case of neonatal NEM with a de novo
c.43G>C (p.Asp15His) TPM3 gene variant localized to
the long arm of chromosome 1(chromosome 1q21.2) which was classified as
likely pathogenic, ACMG category 2, presenting in an autosomal dominant
fashion .NEM with TPM3 gene mutation is a very rare condition
with few cases reported.