Early-onset facioscapulohumeral muscular dystrophy: two case reports

Early onset facioscapulohumeral dystrophy - a systematic review using individual patient data

Infantile or early onset is estimated to occur in around 10% of all facioscapulohumeral dystrophy (FSHD) patients. Although small series of early onset FSHD patients have been reported, comprehensive data on the clinical phenotype is missing. We performed a systematic literature search on the clinical features of early onset FSHD comprising a total of 43 articles with individual data on 227 patients. Additional data from four cohorts was provided by the authors. Mean age at reporting was 18.8 years, and 40% of patients were wheelchair-dependent at that age. Half of the patients had systemic features, including hearing loss (40%), retinal abnormalities (37%) and developmental delay (8%). We found an inverse correlation between repeat size and disease severity, similar to adult-onset FSHD. De novo FSHD1 mutations were more prevalent than in adult-onset FSHD. Compared to adult FSHD, our findings indicate that early onset FSHD is overall characterized by a more severe muscle phenotype and a higher prevalence of systemic features. However, similar as in adults, a significant clinical heterogeneity was observed. Based on this, we consider early onset FSHD to be on the severe end of the FSHD disease spectrum. We found natural history studies and treatment studies to be very scarce in early onset FSHD, therefore longitudinal studies are needed to improve prognostication, clinical management and trial-readiness.

Clinical expression of facioscapulohumeral muscular dystrophy in carriers of 1-3 D4Z4 reduced alleles: experience of the FSHD Italian National Registry

OBJECTIVES

Facioscapulohumeral muscular dystrophy type 1 (FSHD1) has been genetically linked to reduced numbers (≤ 8) of D4Z4 repeats at 4q35. Particularly severe FSHD cases, characterised by an infantile onset and presence of additional extra-muscular features, have been associated with the shortest D4Z4 reduced alleles with 1-3 repeats (1-3 DRA). We searched for signs of perinatal onset and evaluated disease outcome through the systematic collection of clinical and anamnestic records of de novo and familial index cases and their relatives, carrying 1-3 DRA.

SETTING

Italy.

PARTICIPANTS

66 index cases and 33 relatives carrying 1-3 DRA.

OUTCOMES

The clinical examination was performed using the standardised FSHD evaluation form with validated inter-rater reliability. To investigate the earliest signs of disease, we designed the Infantile Anamnestic Questionnaire (IAQ). Comparison of age at onset was performed using the non-parametric Wilcoxon rank-sum or Kruskal-Wallis test. Comparison of the FSHD score was performed using a general linear model and Wald test. Kaplan-Meier survival analysis was used to estimate the age-specific cumulative motor impairment risk.

RESULTS

No patients had perinatal onset. Among index cases, 36 (54.5%) showed the first signs by 10 years of age. The large majority of patients with early disease onset (26 out of 36, 72.2%) were de novo; whereas the majority of patients with disease onset after 10 years of age were familial (16, 53.3%). Comparison of the disease severity outcome between index cases with age at onset before and over 10 years of age, failed to detect statistical significance (Wald test p value=0.064). Of 61 index cases, only 17 (27.9%) presented extra-muscular conditions. Relatives carrying 1-3 DRA showed a large clinical variability ranging from healthy subjects, to patients with severe motor impairment.

CONCLUSIONS

The size of the D4Z4 allele is not always predictive of severe clinical outcome. The high degree of clinical variability suggests that additional factors contribute to the phenotype complexity.

Isolated facial diplegia and very late-onset myopathy in two siblings: atypical presentations of facioscapulohumeral dystrophy

We report two elderly siblings with atypical myopathic weakness due to facioscapulohumeral dystrophy (FSHD). The proband presented with isolated facial diplegia, and her brother developed late onset facial and limb-girdle weakness. Both siblings had a 4q35 deletion with the same residual fragment size (25 kb) confirming FSHD. This report highlights the clinical heterogeneity and intrafamily variability of FSHD.

Facioscapulohumeral dystrophy presenting as infantile facial diplegia and late-onset limb-girdle myopathy in members of the same family

We report a family with markedly variable myopathic weakness due to facioscapulohumeral muscular dystrophy (FSHD). The proband developed mild late-onset proximal limb weakness. Her two daughters had severe infantile facial diplegia, initially diagnosed as Möbius syndrome, and mild childhood-onset limb weakness and scapular winging. Results of facial muscle electromyography and muscle histopathology supported a myopathic disorder. This case study further highlights the broad clinical spectrum and intrafamily variability in FSHD, and the occasional absence of a positive correlation between fragment size and disease onset. Moreover, this study underscores the importance of considering FSHD in cases of infantile facial diplegia, especially in patients not demonstrating the full clinical features of Möbius syndrome. In difficult cases, facial muscle electromyography may help to differentiate myopathic from neuropathic weakness, and help guide further diagnostic studies.