Infantile facioscapulohumeral muscular dystrophy: new observations

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.

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.

Infantile facioscapulohumeral muscular dystrophy revisited: Expansion of clinical phenotypes in patients with a very short EcoRI fragment

Contrary to the classical form, infantile facioscapulohumeral muscular dystrophy (FSHD) usually denotes a severe phenotype and is frequently associated with extramuscular involvements. To elucidate the genotype-phenotype correlation in this severe subgroup, we identified a cohort of nine patients with infantile FSHD who also carried a very short (10-13kb) EcoRI fragment. Their current age ranged from 8 to 33 years and age of onset ranged from 0.4 to 5 years. One patient even manifested his first FSHD-related symptoms at as early as 5 months of age, including inability to smile, poor response to call, and infantile spasms. To date, four patients were wheelchair-bound and six patients had asymmetric weakness. Sensorineural hearing loss and abnormal fundoscopic findings were observed in eight and all of patients respectively. Three with the smallest EcoRI fragments (10-11kb, with normal length being 50-300kb) had mental retardation. Two of these had epilepsy. Cardiac arrhythmias were found in five patients. Restrictive ventilatory defects were observed in seven patients, with one progressing to chronic respiratory failure. Two had swallowing difficulties; one of these required gastrostomy. We identified several rarely reported phenotypes in infantile FSHD, including cardiac arrhythmia, respiratory insufficiency, and swallowing difficulties. There seems to be a correlation between the severity of phenotype and the very short EcoRI fragment in the chromosome 4q35 region. We conclude that the high frequency of multi-organ involvements in this severe FSHD variant suggests the need for an early and multidisciplinary intervention.

[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.

Atypical facet of Möbius syndrome: association with facioscapulohumeral muscular dystrophy

We describe a patient with facioscapulohumeral muscular dystrophy (FSHD) associated with Möbius syndrome and congenital ophthalmoplegia. This 7-year-old girl had profound limitation of extraocular movements since birth, congenital facial diplegia, neonatal hypotonia, and progressive limb-girdle weakness. FSHD genetic testing revealed a pathogenic haplotype with a D4Z4 repeat of 30 kb. The father carries the same allele, although is minimally affected. This unusual case expands the genotypic-phenotypic spectrum of FSHD.

Severe phenotype in infantile facioscapulohumeral muscular dystrophy

While much is known about the clinical course of adult FSHD, the third most common inherited muscular dystrophy, data on the "infantile phenotype" and especially on the progression of the disease in children are limited. We have followed a cohort of 7 patients with infantile FSHD for 9-25 years and here report the clinical and genetic findings in this group. Infantile FSHD is relatively rare, amounting to 4% of all of our FSHD patients. Despite some variability in the progression, infantile FSHD has a more consistent phenotype than adult FSHD. Although they had normal motor milestones, all patients showed facial weakness from early childhood, and subsequently were severely affected with rapid progression of the disease, marked muscular wasting, weakness, and hyperlordosis. None of the patients have shown signs of nocturnal hypoventilation or cardiomyopathy so far. No correlation was found between sex and the severity of phenotype whereas all but one patient had very short fragment sizes of the D4Z4 repeat. Only two patients had a de novo mutation: 3 patients inherited the mutation from a parent with somatic mosaicism, and one was inherited from a parent with classical adult FSHD. One patient was unusual in having one allele inherited from his father who showed somatic mosaicism and one allele with an additional de novo mutation. We conclude that infantile FSHD is a severe and rapidly progressive disease, and this needs to be taken into account in the advice given to patients diagnosed in early childhood. However, our data also suggest that the risk to an individual with classical FSHD of having a child with the infantile form is low.

Floppy infant syndrome

Floppiness/hypotonia is a common neurologic symptom in infancy. A variety of neuromuscular disorders and central nervous system (CNS) disorders cause floppy infant syndrome (FIS). CNS disorders are the much more common causes of the syndrome than neuromuscular disorders. On long-term follow up, cerebral palsy and mental retardation turn out to be the 2 most common causes of FIS. This review focuses on neuromuscular causes of FIS. With the advent of molecular diagnosis, a few conditions can be diagnosed by DNA analysis of the peripheral lymphocytes (myotonic dystrophy, spinal muscular atrophy); however, for the most part, electrodiagnostic studies and muscle biopsy remain as essential diagnostic tools for FIS. Immunohistochemical study of the biopsied muscle also improves diagnostic capability. Management for most conditions remains supportive.

Early-onset facioscapulohumeral muscular dystrophy: two case reports

This report concerns two patients with facioscapulohumeral muscular dystrophy (FSHD) whose facial weakness began in infancy. In both patients, biopsied muscle histology showed mild myogenic changes accompanied by some regenerating and some small angular fibers, while endomysial inflammatory cellular infiltration was observed in Patient 1. The finding that our very young patients had muscle histopathological findings compatible with classical FSHD supports the previously expressed view that muscle histopathology is not related to either age or duration of the disease. Although Patient 2 was a sporadic case, both patients had the abnormal EcoRI DNA fragment detected by Southern blot analysis with probes p13E-11 and pFR-1, a finding compatible with FSHD. This indicates that gene analysis of sporadic cases must be as significant as that of familial cases. This report on patients with very early-onset and with common muscle histopathological and molecular genetic findings should contribute to widening the clinical spectrum of FSHD.

De novo facioscapulohumeral muscular dystrophy defined by DNA probe p13E-11 (D4F104S1)

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant condition with variable age of onset and severity. Identification of a de novo DNA fragment by probe p13E-11 (D4F104S1) established the diagnosis of new mutation FSHD in 27 of 31 sporadic cases. The clinical data for these certain new mutation cases were as follows: 13 boys, 14 girls; mean age of onset 6.8 years; significant leg weakness in 19/27 (70%) (8/27 (30%) used wheelchairs at a mean age of 17.7 years); high tone sensorineural deafness in 10/27; visual acuity and direct ophthalmoscopy were normal. Congenital facial diplegia and sensorineural deafness in three children suggest that infantile FSHD is not a genetically separate disorder from FSHD. Ascertainment bias may explain the difference in severity between this group and typical familial cases. Molecular analysis for FSHD should be considered in children with either congenital or early onset facial weakness or diplegia.

Facioscapulohumeral muscular dystrophy: the impact of genetic research

Recent developments in genetic research have led to the localization and identification of the causative gene defect in a large number of neurological diseases. This paper describes some of the basic principles of molecular genetics and the strategies that have been followed in the search for the gene for facioscapulohumeral muscular dystrophy (FSHD), beginning with the recent localization to chromosome 4q. Many questions remain concerning the pathogenesis and possible genetic heterogeneity of this autosomal dominant myopathy. Hitherto, most evidence favours a genetically homogeneous disorder, but only the isolation and detailed characterization of the FSHD gene will resolve these issues completely.

Genetic counselling in facioscapulohumeral muscular dystrophy

Clinical data are presented from a survey of 41 families with dominantly inherited facioscapulohumeral muscular dystrophy (FSHD) in which over 500 family members were examined, including 168 affected subjects. New mutation could account for six isolated cases. Results suggest that 33% of heterozygotes over 40 years are mildly affected and a majority develop significant lower limb weakness; 19% over 40 years require wheelchairs. Presymptomatic testing of serum creatine kinase level (CK) is limited as a raised level occurs in only 80% of affected males under 40 years and 48% of affected women. Distribution of weakness, severity, age at onset, and CK varied between subjects, but provided no clinical evidence for genetic heterogeneity in a comparison between the 11 largest families. The conclusion of genetic homogeneity in FSHD, including subjects previously diagnosed as FSH type spinal muscular atrophy, is strongly supported by recent genetic linkage data.

Locomotor problems in infantile facioscapulohumeral muscular dystrophy. Retrospective study of 9 patients

A retrospective study of 9 patients with infantile facioscapulohumeral muscular dystrophy defines orthopedic deformities and progression. Patients presented in the early months of life with facial diplegia. Sensorineural hearing loss occurred in 8 out of 9 with a mean onset at 5 (2-9) years. Walking began at the normal time, but worsened progressively, which was due mainly to gluteus maximus muscle weakness. Scapular winging, extreme lumbar lordosis, and foot drop were characteristic. The majority of patients (in this and other series) lose walking ability in the second decade. Efforts to control lumbar lordosis by bracing while the patients were still walking were ineffective. Control of lumbar lordosis after the patients are wheelchair-dependent is important.

Atypical facio-scapulo-humeral muscular dystrophy--a counselling dilemma

In an isolated male patient, differentiation between Facio-Scapulo-Humeral Muscular Dystrophy (FSH) and Becker Muscular Dystrophy (BMD) may be difficult. To emphasise this point, we report a patient, whose features are atypical of FSH. Details of his daughter who now manifests similar presenting features, are provided. The pitfalls posed for the genetic counsellor by FSH presenting in an atypical manner which clinically overlaps with genetically distinct conditions are discussed in the light of this pedigree.

X-linked and FSH dystrophies in one family

A family is reported in which the father was affected by facioscapulohumeral muscular dystrophy FSHD. One son was affected by Duchenne muscular dystrophy (DMD). The second son died at the age of 3 yr of a severe primary muscle disease and it is suggested that this was the outcome of dual expression of the two conditions.

Facioscapulohumeral muscular dystrophy: evidence for selective, genetic electrophysiologic cardiac involvement

Facioscapulohumeral muscular dystrophy is an autosomal dominant disorder with an incidence of 3 to 10 cases per million. The only type of cardiac involvement ascribed to this neuromuscular disorder is a unique form of heart disease--permanent atrial paralysis. However, reported cases of facioscapulohumeral muscular dystrophy probably represented instead what is now recognized as phenotypically similar Emery-Dreifuss dystrophy. Cardiac involvement, therefore, has not been convincingly reported in facioscapulohumeral muscular dystrophy, but because of the clinical similarity of that disorder to Emery-Dreifuss dystrophy and its genetic variants, a prospective investigation of the electrophysiologic properties of the atria and atrioventricular (AV) node and infranodal conduction was undertaken in 30 rigorously documented cases of facioscapulohumeral muscular dystrophy. All patients had a 12 lead surface electrocardiogram (ECG), 22 had a 24 h ambulatory ECG, 15 patients had two-dimensional echocardiographic/Doppler studies and 10 patients underwent 12 intracardiac electrophysiologic investigations. Left atrial, right atrial or biatrial P wave abnormalities were present in 60% of the surface ECGs. Evidence of abnormal AV node or infranodal conduction was present on intracardiac electrophysiologic study or surface ECG in 27% of patients. Atrial flutter or fibrillation was induced by single atrial extra stimuli in 10 of the 12 intracardiac electrophysiologic studies. Sinus node function was abnormal in three patients. This investigation provides the first secure evidence of cardiac involvement in facioscapulohumeral muscular dystrophy. The involvement is represented by relatively high susceptibility to induced atrial flutter or fibrillation during electrophysiologic study, together with less frequent evidence of abnormal sinus node function and abnormal AV node or infranodal conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Estimation of age dependent penetrance in facioscapulohumeral muscular dystrophy by minimising ascertainment bias

In any family study using information gathered retrospectively, the influence of the method of ascertainment on the observed segregation ratio in sibships needs careful consideration. The study of kindred members from outside the area of primary ascertainment is invaluable in providing segregation data with minimal ascertainment bias. For facioscapulohumeral muscular dystrophy (FSHD), using this approach, and based on the presence or absence of characteristic clinical signs rather than on an historical account of age at onset, estimates were derived for penetrance of the FSHD gene of less than 5% for ages 0 to 4 years, 21% for ages 5 to 9, 58% for ages 10 to 14, 86% for ages 15 to 19, and 95% penetrance for age 20 years and over. No difference between families was identified. These figures should facilitate genetic counselling and the interpretation of genetic linkage study results in FSHD.