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.