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

Phenotypic Variability Among Patients With D4Z4 Reduced Allele Facioscapulohumeral Muscular Dystrophy

IMPORTANCE

Facioscapulohumeral muscular dystrophy (FSHD) is considered an autosomal dominant disorder, associated with the deletion of tandemly arrayed D4Z4 repetitive elements. The extensive use of molecular analysis of the D4Z4 locus for FSHD diagnosis has revealed wide clinical variability, suggesting that subgroups of patients exist among carriers of the D4Z4 reduced allele (DRA).

OBJECTIVE

To investigate the clinical expression of FSHD in the genetic subgroup of carriers of a DRA with 7 to 8 repeat units (RUs).

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cross-sectional study included 422 carriers of DRA with 7 to 8 RUs (187 unrelated probands and 235 relatives) from a consecutive sample of 280 probands and 306 relatives from the Italian National Registry for FSHD collected between 2008 and 2016. Participants were evaluated by the Italian Clinical Network for FSHD, and all clinical and molecular data were collected in the Italian National Registry for FSHD database. Data analysis was conducted from January 2017 to June 2018.

MAIN OUTCOMES AND MEASURES

The phenotypic classification of probands and relatives was obtained by applying the Comprehensive Clinical Evaluation Form which classifies patients in the 4 following categories: (1) participants presenting facial and scapular girdle muscle weakness typical of FSHD (category A, subcategories A1-A3), (2) participants with muscle weakness limited to scapular girdle or facial muscles (category B, subcategories B1 and B2), (3) asymptomatic or healthy participants (category C, subcategories C1 and C2), and (4) participants with myopathic phenotypes presenting clinical features not consistent with FSHD canonical phenotype (category D, subcategories D1 and D2).

RESULTS

A total of 187 probands (mean [SD] age at last neurological examination, 53.5 [15.2] years; 103 [55.1%] men) and 235 relatives (mean [SD] age at last neurologic examination, 45.1 [17.0] years; 104 [44.7%] men) with a DRA with 7 to 8 RUs and a molecular diagnosis of FSHD were evaluated. Of 187 probands, 99 (52.9%; 95% CI, 45.7%-60.1%) displayed the classic FSHD phenotype, whereas 86 (47.1%; 95% CI, 39.8%-54.3%) presented incomplete or atypical phenotypes. Of 235 carrier relatives from 106 unrelated families, 124 (52.8%; 95% CI, 46.4%-59.7%) had no motor impairment, whereas a small number (38 [16.2%; 95% CI, 9.8%-23.1%]) displayed the classic FSHD phenotype, and 73 (31.0%; 95% CI, 24.7%-38.0%) presented with incomplete or atypical phenotypes. In 37 of 106 families (34.9%; 95% CI, 25.9%-44.8%), the proband was the only participant presenting with a myopathic phenotype, while only 20 families (18.9%; 95% CI, 11.9%-27.6%) had a member with autosomal dominant FSHD.

CONCLUSIONS AND RELEVANCE

This study found large phenotypic variability associated with individuals carrying a DRA with 7 to 8 RUs, in contrast to the indication that a positive molecular test is the only determining aspect for FSHD diagnosis. These findings suggest that carriers of a DRA with 7 to 8 RUs constitute a genetic subgroup different from classic FSHD. Based on these results, it is recommended that clinicians use the Comprehensive Clinical Evaluation Form for clinical classification and, whenever possible, study the extended family to provide the most adequate clinical management and genetic counseling.

Motor exam of patients with spinal cord injury: a terminological imbroglio

The description of the motor deficit of patients with spinal cord injury (SCI) varies significantly, leading to confusion within the neurological terminology. This paper proposes a concise and easy to use terminology to describe the motor deficit of patients with SCI. A broad review of the origin of the nomenclature used to describe the motor deficit of patients with SCI was performed and discussed. The prefix: "hemi" should be used to describe paralysis of one half of the body; "mono" for one limb; "para" for lower limbs, di" for two symmetrical segments and/or parts in both sides of the body; "tri" for three limbs, or two limbs and one side of the face; and "tetra" for four limbs. The suffix: "plegia" should be used for total paralysis of a limb or part of the body, and "paresis" for partial paralysis. The term "brachial" refers to the upper limbs; and "podal" to the lower limbs. According to the spinal cord origin of the main key muscles for the limbs, patients with complete injury affecting spinal cord segments C1-5 usually presents with "tetraplegia"; C6-T1 presents with "paraplegia and brachial diparesis"; T2-L2 with "paraplegia"; and L3-S1 with "paraparesis".

Facioscapulohumeral Muscular Dystrophy: More Complex than it Appears

Facioscapulohumeral muscular dystrophy (FSHD) has been classified as an autosomal dominant myopathy, linked to rearrangements in an array of 3.3 kb tandemly repeated DNA elements (D4Z4) located at the 4q subtelomere (4q35). For the last 20 years, the diagnosis of FSHD has been confirmed in clinical practice by the detection of one D4Z4 allele with a reduced number (≤8) of repeats at 4q35. Although wide inter- and intra-familial clinical variability was found in subjects carrying D4Z4 alleles of reduced size, this DNA testing has been considered highly sensitive and specific. However, several exceptions to this general rule have been reported. Specifically, FSHD families with asymptomatic relatives carrying D4Z4 reduced alleles, FSHD genealogies with subjects affected with other neuromuscular disorders and FSHD affected patients carrying D4Z4 alleles of normal size have been described. In order to explain these findings, it has been proposed that the reduction of D4Z4 repeats at 4q35 could be pathogenic only in certain chromosomal backgrounds, defined as "permissive" specific haplotypes. However, our most recent studies show that the current DNA signature of FSHD is a common polymorphism and that in FSHD families the risk of developing FSHD for carriers of D4Z4 reduced alleles (DRA) depends on additional factors besides the 4q35 locus. These findings highlight the necessity to re-evaluate the significance and the predictive value of DRA, not only for research but also in clinical practice. Further clinical and genetic analysis of FSHD families will be extremely important for studies aiming at dissecting the complexity of FSHD.

Focal and other unusual presentations of facioscapulohumeral muscular dystrophy

INTRODUCTION

Facioscapulohumeral dystrophy (FSHD) presents classically with facial and shoulder-girdle weakness. We report focal atypical presentations of FSHD. Our aim was to identify focal/unusual phenotypes in genetically confirmed FSHD cases.

METHODS

We undertook a retrospective review of an academic center database of the period from 1996 to 2011. Of 139 FSHD cases, 7 had atypical genetically confirmed disease. Clinical data were abstracted.

RESULTS

Seven cases (4 men) had a mean age of 37 years at onset (range 18-63 years) and mean 43 years at diagnosis (range 20-74 years). Presenting symptoms were monomelic lower limb (n = 3) or upper limb (n = 2) atrophy, or axial weakness (n = 2). Five patients had focal weakness on examination. CK was normal to borderline high. Two patients had a relative with FSHD. Coexistent unusual features included dyspnea (n = 1), S1 radicular pain with calf atrophy (n = 2), and peripheral neuropathy (n = 1). Almost all patients had myopathic EMG changes. DNA analysis showed a D4Z4 EcoRI fragment size ranging from 20 to 37 kilobases.

CONCLUSIONS

FSHD may present with focal weakness, dyspnea and myopathic EMG changes. These findings should raise the possibility of FSHD.

Elderly onset of weakness in facioscapulohumeral muscular dystrophy

A 77-year-old male is presented. He had onset of proximal weakness 10 years earlier. His course was slowly progressive. Despite having phenotypic features of facioscapulohumeral muscular dystrophy (FSH), genetic testing for this was delayed because of his age of onset, lack of family history, and benign appearing muscle biopsy. This case is one of the oldest onset of weakness in genetically confirmed FSH and highlights the recognized expansion in phenotype that has occurred since the advent of genetic testing.

Tetraplegia or paraplegia with brachial diparesis? What is the most appropriate designation for the motor deficit in patients with lower cervical spinal cord injury?

The authors seek to clarify the nomenclature used to describe cervical spinal cord injuries, particularly the use of the terms "tetraplegia", "quadriplegia", "quadriparesis", "tetraparesis", "incomplete quadriplegia" or "incomplete tetraplegia" when applied to patients with lower cervical cord injuries. A review of the origin of the terms and nomenclature used currently to describe the neurological status of patients with SCI in the literature was performed. The terms "tetraplegia", "quadriplegia", "quadriparesis", "tetraparesis", "incomplete quadriplegia" or "incomplete tetraplegia" have been used very often to describe patients with complete lower cervical SCI despite the fact that the clinical scenario is all the same for most of these patients. Most of these patients have total loss of the motor voluntary movements of their lower trunk and inferior limbs, and partial impairment of movement of their superior limbs, preserving many motor functions of the proximal muscles of their arms (superior limbs). A potentially better descriptive term may be "paraplegia with brachial diparesis". In using the most appropriate terminology, the patients with lower cervical SCI currently referred as presenting with "tetraplegia", "quadriplegia", "quadriparesis", "tetraparesis", "incomplete quadriplegia" or "incomplete tetraplegia", might be better described as having "paraplegia with brachial diparesis".

[Facioscapulohumeral muscular dystrophy. Clinical picture, atypical forms, diagnostics, genetics]

The classic phenotype of the facioscapulohumeral muscular dystrophy (FSHD) includes an initially restricted pattern of asymmetric weakness of facial and shoulder girdle muscles. Disease progression is usually slow and typically accompanied by foot extensor muscle weakness and pelvic girdle weakness. Atypical patterns of FSHD that include isolated camptocormia and facial muscle sparing exceed current diagnostic criteria. No causal genetic lesion in FSHD has been identified yet. In the vast majority of cases, FSHD results from a heterozygous partial deletion of a critical number of repetitive elements (D4Z4) on chromosome 4q35 (4qA allele). Molecular diagnostic testing is appropriate to confirm the diagnosis of FSHD without need for muscle biopsy. Penetrance of this dominantly inherited disorder is high, exhibiting a great phenotypic variability in clinical pattern and disease progression even among affected members of the same family.