Spinal muscular atrophy (SMA) is a lower motor neuron disease with autosomal recessive inheritance. The first cases of SMA were reported by Werdnig in 1891. Although the phenotypic variation of SMA led to controversy regarding the clinical entity of the disease, the genetic homogeneity of SMA was proved in 1990. Five years later, in 1995, the gene responsible for SMA, SMN1, was identified. Genetic testing of SMN1 has enabled precise epidemiological studies, revealing that SMA occurs in 1 of 10,000 to 20,000 live births and that more than 95% of affected patients are homozygous for SMN1 deletion. In 2016, nusinersen was the first drug approved for treatment of SMA in the United States. Two other drugs were subsequently approved: onasemnogene abeparvovec and risdiplam. Clinical trials with these drugs targeting patients with pre-symptomatic SMA (those who were diagnosed by genetic testing but showed no symptoms) revealed that such patients could achieve the milestones of independent sitting and/or walking. Following the great success of these trials, population-based newborn screening programs for SMA (more precisely, SMN1-deleted SMA) have been increasingly implemented worldwide. Early detection by newborn screening and early treatment with new drugs are expected to soon become the standards in the field of SMA.

Duchenne and Becker muscular dystrophies (DMD/BMD) are X-linked inherited muscular disorders caused by mutations in the dystrophin gene. Two-thirds of DMD cases are thought to be caused by inheritance from carrier mothers and this study aimed to clarify and compare the carrier frequency of mothers of DMD and BMD patients according to the mutation type. We included 139 DMD and 19 BMD mothers. Of these, 113 patients (99 DMD and 14 BMD) and 13 patients (12 DMD and 1 BMD) had deletions and duplications of one or more exons, respectively. Small mutations, including nonsense mutations, small deletions/insertions and splice site mutations, were identified in 32 patients (28 DMD and four BMD). The overall carrier frequency for BMD mothers was significantly higher than for DMD (89.5% vs 57.6%, P<0.05), probably as BMD patients can leave descendants. The carrier frequency tended to be lower in mothers of DMD patients with deletion mutations than with duplications and small mutations (53.5%, 66.7% and 67.9%, respectively). It was suggested that de novo mutations are more prevalent for deletions than other mutations. This is the first report to analyze the carrier frequency according to mutation type.

TAFRO syndrome is a unique clinicopathologic variant of multicentric Castleman’s disease that has recently been identified in Japan. It is characterized by a constellation of symptoms: Thrombocytopenia, Anasarca, reticulin Fibrosis of the bone marrow, Renal dysfunction and Organomegaly (TAFRO). Previous reports have shown that affected patients usually respond to immunosuppressive therapy, but the disease sometimes has a fatal course. TAFRO syndrome occurs in the middle-aged and elderly and there are no prior reports of the disease in adolescents. Here we report the first adolescent case, successfully treated with anti-IL-6 receptor antibody (tocilizumab, TCZ) and monitored with serial cytokine profiles.

Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder that causes degeneration of anterior horn cells in the human spinal cord and subsequent loss of motor neurons. The severe form of SMA is among the genetic diseases with the highest infant mortality. Although SMA has been considered incurable, newly developed drugs—nusinersen and onasemnogene abeparvovec—improve the life prognoses and motor functions of affected infants. To maximize the efficacy of these drugs, treatments should be started at the pre-symptomatic stage of SMA. Thus, newborn screening for SMA is now strongly recommended. Herein, we provide some data based on our experience of SMA diagnosis by genetic testing in Japan. A total of 515 patients suspected of having SMA or another lower motor neuron disease were tested. Among these patients, 228 were diagnosed as having SMA with survival motor neuron 1 (SMN1) deletion. We analyzed the distribution of clinical subtypes and ages at genetic testing in the SMN1-deleted patients, and estimated the SMA incidence based on data from Osaka and Hyogo prefectures, Japan. Our data showed that confirmed diagnosis by genetic testing was notably delayed, and the estimated incidence was 1 in 30,000–40,000 live births, which seemed notably lower than in other countries. These findings suggest that many diagnosis-delayed or undiagnosed cases may be present in Japan. To prevent this, newborn screening programs for SMA (SMA-NBS) need to be implemented in all Japanese prefectures. In this article, we also introduce our pilot study for SMA-NBS in Osaka Prefecture.