Congenital muscular dystrophy with laminin α2 chain deficiency: Identification of a new intermediate phenotype and correlation of clinical findings to muscle immunohistochemistry

The laminins comprise of a family of heterotrimeric proteins of the extracellular matrix. The cross-shaped proteins consist of a heavy α-chain and two light chains, called β and γ. Each group of chains, classified on their sequence identity and domain organization, include different isoforms. A deficiency of the α2 chain of laminin-2, previously termed merosin or M component, was shown to be responsible for one form of congenital muscular dystrophy (CMD). We investigated muscle biopsies of 20 patients with the clinical diagnosis of CMD and histological evidence of muscular dystrophy for the expression of different laminin chains. Patients with evidence of pachygyria/lissencephaly of the CNS were excluded from this series. The immunohistochemical analysis was correlated to clinical findings and MRI data of the brain. Of 20 patients, 11 (55%) revealed complete or near-complete deficiency of the α2 chain in their skeletal muscle specimens. So far none of these patients became ambulant. Of 20 patients 2 showed partial but clear-cut α2 chain-deficiency. These two patients became ambulant at 18 months and 3 years. All 13 patients with complete or partial α2 chain-deficiency demonstrated cerebral white matter changes on MRI. In contrast, 6/7 CMD patients with normal α2 chain expression became ambulant and none of the 6/7 tested showed evidence of cerebral abnormal T2 sequence signal of the myelin on MRI.     

Progressive Muscular Dystrophy in Infancy

Clinical features of 11 cases of muscular dystrophy in infancy were discussed. From the detailed symptomatological analysis of the 11 patients we reported here, we found two subgroups of infantile muscular dystrophy. There were 6 cases of congenital cerebro-muscular dystrophy (Fukuyama) and 5 cases characterized by comparatively late onset, no sexual preference, proximally dominant muscle wasting, infrequence of associated joint contractures, normal facial muscle and no mental deficiency. The characteristics of this latter group in infantile muscular dystrophy are similar to those of limb-girdle muscular dystrophy. It is suggested that some of the patients with limb-girdle type of muscular dystrophy may have its onset in infancy.     

Distinguishing Cardiac Features of a Novel Form of Congenital Muscular Dystrophy (Salih CMD)

The cardiac features of a novel form of congenital muscular dystrophy (Salih CMD) are described in two adolescent siblings. The patients presented with severe hypotonia at birth, associated with delayed development. They could walk independently and managed to maintain walking after 13 years of age. Their muscle immunohistochemistry differed from that seen in Duchenne and Becher muscular dystrophy (DMD and BMD), severe childhood autosomal recessive muscular dystrophy (SCARMD) due to sarcoglycan deficiency (sarcoglycanopathies), and lamininα2 (merosin)-deficient CMD. However, both patients had associated cardiomyopathy. Electrocardiography (ECG) in Salih CMD was characterized by delayed atrioventricular (AV) conduction, left anterior fascicular block (left axis deviation), and left atrial enlargement without evidence of atrial dysarrhythmia. Echocardiography showed features of severe left ventricular dysfunction with estimated left ventricle ejection fraction (LVEF) of 25% at 16 years-of-age in the older patient. A year later, multigated aquisition MUGA scan showed LVEF of 21% and dilatation of the right ventricle. Echocardiography and MUGA scan were normal in the younger patient at 15 years-of-age. ECG, echocardiography, and MUGA scan are effective techniques for diagnosing and monitoring the cardiomyopathy in Salih CMD. They can also distinguish it from features seen in the other common forms of MD, including DMD, BMD, and sarcoglycanopathies.     

先天性肌营养不良的诊断及层黏连蛋白表达的意义

目的 探讨先天性肌营养不良（CMD）的临床诊断、肌肉免疫组织化学特点及随访情况。方法 对8例CMD患儿的病例资料进行综合分析,并进行肌肉活检,利用抗层黏连蛋白以（laminin α2,又称merosin）、α抗肌萎缩相关糖蛋白（α-dystroglycan,α-DG）和β抗肌萎缩相关糖蛋白（β-dystroglycan,β-DG）抗体行肌肉活检组织免疫组织化学染色。结果 8例均于出生时或生后半年之内出现肌无力、肌张力低下,有的合并关节挛缩、喂养困难或呼吸功能不全。肌肉病理检查均发现肌营养不良改变特点。其中merosin染色阴性者4例,头颅MRI示脑白质髓鞘化不良;4例为merosin染色阳性,呈散发或常染色体隐性遗传,2例合并有智力低下,抗α-DG（1IH6）抗体染色显示α-DG糖基化低下,其中1例伴视神经萎缩,头颅MRI提示脑结构异常。结论 本组CMD中merosin染色既有阴性,也有阳性,merosin缺乏症（先天性肌营养不良1A型）更为常见,伴随脑白质病变。merosin染色阳性者中存在抗肌萎缩相关糖蛋白糖基化低下病例。     

Merosin-deficient congenital muscular dystrophy and cortical dysplasia.

Congenital muscular dystrophy (CMD) encompasses a heterogenous group of muscle disorders with autosomal recessive inheritance, characterized by muscular weakness and hypotonia at birth or within the first few months of life and developmental delay. Merosin-deficient CMD is a clinically distinct form which may be associated with significant abnormalities of the brain detectable by neuroimaging. We report two siblings of consanguineous parents with merosin-deficient CMD in an Irish family who in addition to the characteristic white matter abnormalities on neuroimaging, had occipital dysplasia. Clinical, electrophysiological muscle biopsy findings and neuroimaging were very similar in both cases. Although merosin-deficient CMD with white matter abnormalities on neuroimaging is well documented in the literature, the association with occipital dysplasia has only rarely been reported. The appearance of an identical cortical defect in these siblings suggests an underlying genetic mechanism.     

Identification of a novel compound heterozygote SCO2 mutation in cytochrome c oxidase deficient fatal infantile cardioencephalomyopathy

Fatal infantile cardioencephalomyopathy (OMIM No. 604377) is a disorder of the mitochondrial respiratory chain and is characterised by neonatal progressive muscular hypotonia and cardiomyopathy because of severe Cytochrome c oxidase deficiency. Here we report a novel mutation in the Cytochrome c oxidase assembly gene SCO2 in an infant with fatal infantile cardioencephalomyopathy despite normal initial metabolic screening. CONCLUSION: In newborns with unexplained muscular hypotonia and cardiomyopathy genetic testing of mitochondrial respiratory chain disorders might be helpful to establish a final diagnosis and guide treatment decisions.     

Serum levels of carboxyterminal propeptide of type I procollagen, aminoterminal propeptide of type III procollagen and laminin P1 in Duchenne muscular dystrophy

The striking proliferation of connective tissue in Duchenne muscular dystrophy is attributed, besides other components of the extracellular matrix, to an increase of endomysial and perimysial type III and type I collagen. We investigated if muscle fibrosis correlates to an increased serum concentration of procollagen I or HI. Therefore, we measured the serum levels of carboxyterminal propeptide of type I procollagen, aminoterminal propeptide of type III procollagen and laminin P1 in 20 boys with progressive muscular dystrophy (16 definite Duchenne muscular dystrophy, 2 suspected of Duchenne muscular dystrophy, 2 Becker muscular dystrophy). In contrast to collagen I and III the expression of laminin in the basement membrane is known to be normal in Duchenne muscular dystrophy. There was no significant alteration of serum concentration of procollagen ni N-peptide, procollagen I C-peptide and laminin PI in boys with Duchenne muscular dystrophy. Measuring these parameters is not useful for investigating the extent of muscle fibrosis or for monitoring the effect of therapeutic trials such as steroid treatment.     

Kongenitale Muskeldystrophie

Zusammenfassung Es wird über vier Kinder mit kongenitaler Muskeldystrophie berichtet. Alle Patienten boten bereits bei der Geburt das typische klinische Bild mit Schwäche und Hypotonie einer mangelhaft angelegten Muskulatur. Die Diagnose wurde histologisch gesichert. Dabei waren Veränderungen zu beobachten, die dem Endstadium der progressiven Muskeldystrophie entsprechen: Atrophierte und (pseudo)hypotrophierte Muskelfasern mit deutlichen Kaliberschwankungen; Vermehrung des peri- und endomysialen Bindegewebes sowie interstitielle Makrophagenaktivierung.Bei einer Patientin (B. H.) war der Nachweis eines IgG-Paraproteins bemerkenswert; ein solcher Befund ist bisher nicht beschrieben worden.

---

Congenital muscular dystrophy

Four cases of congenital muscular dystrophy are reported. All patients presented a clinical picture which was characterized by muscular weakness and hypotonia already manifest at birth. The diagnosis was confirmed by a muscle biopsy. The histological findings were similar to those observed in the final stage of progressive muscular dystrophy: Atrophic and (pseudo) hypertrophic fibres with great variations in size, an increase of perimysial and endomysial connective tissue, and an interstitial activation of macrophages.In one case (B. H.) an IgG-paraproteinemia was found which seems remarkable; similar observations in combination with muscular dystrophy have not yet been described in the literature.

Herrn Professor Dr. K. H. Schäfer zum 60. Geburtstag     

Epilepsy in Duchenne and Becker muscular dystrophies.

Duchenne and Becker muscular dystrophies are X-linked allelic disorders in which the association of central nervous system dysfunction, typically in the form of mental retardation, is a well recognized feature. They are both due to mutations in the dystrophin gene, whose corresponding protein products are expressed both in the muscle and central nervous system. We have observed an increased frequency of epilepsy in children with Duchenne and Becker muscular dystrophy attending our clinic. Out of 254 boys with this condition (201 Duchenne and 53 Becker), eight children, four in the Duchenne and four in the Becker group, had a confirmed diagnosis of epilepsy (cumulative incidence 3.14%, with a subgroup incidence of 1.99% in the Duchenne and 7.54% in the Becker group). Statistical analysis indicated that only the incidence of epilepsy in Becker muscular dystrophy was significant (p < 0.007). Our data suggests that epilepsy may be a rare associated feature in children with muscular dystrophy secondary to dystrophin deficiency.     

进行性肌营养不良患儿肌肉组织转化生长因子-β_1的表达

目的　进行性肌营养不良肌纤维化的病理机制不清。转化生长因子 β1(TGF β1)能诱导细胞外基质的积聚 ,对纤维发生和组织修复起调节作用。本研究探讨进行性肌营养不良患儿肌肉TGF β1表达与肌纤维化的关系 ,阐明儿童进行性肌营养不良肌纤维化慢性病理进展的部分机制。方法　采用免疫荧光和免疫印迹的方法检测 18例进行性肌营养不良患儿 [7例Duchenne肌营养不良 (DMD) ,6例福山型和 3例非福山型先天性肌营养不良 (FCMD ,nFCMD) ,2例Becker型肌营养不良 (BMD) ]和 13例非神经肌肉疾病患者肌肉组织中TGF β1表达。结果　先天性肌营养不良 (CMD)和DMD肌组织内潜伏和活性形式的TGF β1均免疫定位于肌纤维和间质的肌内膜 ,表达强度以CMD为著。免疫印迹结果显示FCMD肌肉组织TGF β1表达强于DMD和对照。结论　在儿童进行性肌营养不良的肌肉慢性病理进展中 ,肌肉纤维化可能是重要原因之一。     

Atypical phenylketonuria due to biopterin deficiency. Early treatment with tetrahydrobiopterin and neurotransmitter precursors, trials of monotherapy

This report presents the first case where an infant with tetrahydrobiopterin deficiency has been identified by screening of newborns with hyperphenylalaninemia for tetrahydrobiopterin deficiency. Therapy with L-Dopa, 5-hydroxytryptophan, Carbidopa and tetrahydrobiopterin was started at the age of seven weeks while the child received a normal diet. At that time already muscular hypotonia was observed. The girl, now 2 1/2 years old, shows slight muscular hypotonia and hypomotility, short periods of hypertonic extension of the limbs, and retardation of sensomotor and mental development of about 6-8 months. Monotherapy with tetrahydrobiopterin dihydrochloride, 20-40 mg/kg b.w., diminished the muscular hypotonia. The effect lasted however for only about 1 day. While urinary serotonin and phenylalanine remained normal for at least 3 days and neopterin was only slightly elevated, urinary free dopamine however remained low. Similar results were obtained after 1',2'-diacetyl tetrahydrobiopterin dihydrochloride administration, 20 mg/kg b.w.     

An early onset muscular dystrophy with diaphragmatic involvement, early respiratory failure and secondary alpha2 laminin deficiency unlinked to the LAMA2 locus on 6q22.

We present four subjects from one family and one subject (with an affected sibling who had died) from a second, unrelated family, with early onset, Duchenne-like, muscular dystrophy who presented with proximal girdle weakness, calf and generalized muscle hypertrophy, selective wasting of the sternomastoid muscles, rigidity of the spine and contractures of the tendo Achilles. Intellect was normal. Serum creatine kinase was grossly elevated and the muscle biopsies showed a dystrophic picture. All five subjects have developed early respiratory failure due to severe diaphragmatic involvement; two have already died aged 4 and 7 years of age and the remaining three are dependent on night time ventilation. There has been very little deterioration over time in the skeletal muscle function, and the survivors remain ambulant, the oldest being 11 years. Immunocytochemical studies of the muscle biopsy showed a normal pattern for dystrophin and the dystrophin-associated glycoproteins, but a reduction of the laminin alpha2 chain of merosin. Magnetic resonance imaging of the brain was normal. The disease did not link to the LAMA2 locus for laminin alpha2 on chromosome 6q, so that these families seem to represent a new form of autosomal recessive muscular dystrophy with a secondary merosin deficiency. The primary protein deficiency has not yet been identified.     

结缔组织生长因子在进行性肌营养不良中的表达

目的探讨结缔组织生长因子（CTGF）在进行性肌营养不良（PMD）中的作用。方法使用Duchenne型肌营养不良（DMD）8例、Becker型肌营养不良（BMD）2例、先天性肌营养不良（CMD）6例患儿的肌肉活检标本,借助免疫组织化学、双免疫荧光方法及Western印迹分析检测CTGF的免疫表达和定位。结果免疫组织化学和双免疫荧光法显示CTGF在正常肌肉的血管处明显表达;免疫组织化学法和Western印记分析均显示在PMD的萎缩肌肉中CTGF的免疫反应明显增强,所有病变肌肉组织中,CTGF在再生纤维的膜、胞浆及胞核中、巨噬细胞及巨噬细胞浸润的坏死纤维中强烈表达,也免疫定位在非再生纤维的肌纤维膜、肌内膜及肌束膜的结缔组织中;双免疫标记显示在肌内膜及肌束膜的大多数激活的成纤维细胞表达CTGF;但年长的CMD患儿的晚期纤维化中CTGF弱表达或无表达。结论结果表明CTGF可能参与了PMD的发病过程,肌肉内的CTGF可能在肌纤维再生和肌肉纤维化的病变过程中起重要作用。     

The floppy infant: a practical approach

Cerebral, non paralytic and peripheral paralytic hypotonia are briefly discussed. Criteria which help in the differential diagnosis are emphasized. In the usual cerebral hypotonia, muscle strength is preserved but muscle tone is decreased. However, there are a few conditions in which cerebral hypotonia is severe enough to resemble paralytic hypotonia. These conditions include the Prader-Willi syndrome (first phase), the Zellweger syndrome and some cases of congenital myotonic dystrophy. In peripheral or paralytic hypotonia muscle weakness and hypotonia go hand-in-hand. A few practical diagnostic criteria are given which allow the differentiation between anterior horn cell disease, polyneuropathy, neonatal myasthenia and myopathy. Finally, essential or benign hypotonia is briefly alluded to.     

A Case With the Infantile Type of Glycerol Kinase Deficiency

A male infant with the infantile type of glycerol kinase deficiency is described. At six years of age, he showed proximal dominant muscle atrophy and weakness, addisonian pigmentation and mental retardation. Laboratory investigations revealed muscular dystrophy, adrenal insufficiency and glycerol kinase deficiency. He has a small deletion in a band (Xp21) of the X chromosome. The clinical, biochemical and genetic findings in this patient are reported.     

假肥大型肌营养不良的诊断进展

假肥大型肌营养不良是由于dystrophin基因突变引起的X连锁隐性遗传性疾病,表现为肌束内大量脂肪和结缔组织的堆积,导致高致残、致死率.由于该病迄今无特异性治疗,只能对症治疗和支持治疗,所以准确、全面的检测对假肥大肌营养不良患者及携带者有着重要的意义,有助于产前检测避免此类患儿的出生,也是目前解决这一问题的关键所在.该文就血清酶学、肌电生理学、影像学、肌组织病理活检及基因检测等诊断假肥大型肌营养不良的方法进行综述.     

Congenital myotonic dystrophy

Myotonic muscular dystrophy is the most frequent autosomal muscular dystrophy affecting adults and children. It affects multiple organ systems and is probably the best example of variable expressivity in a human disease. This article presents a patient with congenital myotonic dystrophy who had facial dysmorphism, hypotonia, talipes, feeding and respiratory difficulties in the neonatal period and later presented to us with developmental delay and had percussion myotonia. His mother had clinical and electrophysiological features of myotonia. Expansion of unstable CTG trinucleotide repeat in the myotonic protein kinase gene was demonstrated in both. The identification of this molecular defect allows its specific diagnosis in relation to other neuromuscular disorders as well as accurate prenatal diagnosis.     

Familial congenital muscular dystrophy caused by phosphofructokinase deficiency]

Two children, born to related parents, presented since birth a muscular defect rapidly complicated by painful joint stiffness. The oldest child died at 6 months of age, from respiratory complications. The second-14 month old- does not sit without support. The muscle fibres are of unequal calibre and numerous fibres have under-sarcolemmal PAS positive areas contain glycogen, as seen on electron microscopy. In the second patient, the biochemical analysis showed a moderate glycogen accumulation and muscular enzymatic studies demonstrated an isolated and major deficiency in phosphofructokinase activity. Activity was normal in red blood cells and in fibroblasts cultured in vitro. Hence, these cases should be distinguished from formerly reported cases of phosphofructokinase deficiency. This type of P.F.K. deficiency should be looked for in patients with severe congenital muscular dystrophy and early joint involvement.     

Dystrophin Abnormality in Progressive Muscular Dystrophy -A Review Article-

Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disorder of muscle in children, with an incidence of approximately 1 in 3,300 male births. In about a third of affected boys, the disease is due to a new mutation, and most patients die in their early 20s. Over the last few years, the genetic, biochemical and histopathological basis of DMD has been elucidated greatly. In particular, the discovery of "dystrophin," the protein product of the DMD gene is truly an epoch-making success in the history of muscular dystrophy research. Dystrophin is now thought to be a cytoskeletal protein underlying the plasma membrane (known in muscle as the sarcolemma) of normal muscle fiber, and is undetectable or greatly reduced in DMD. In this review article, dystrophin in normal skeletal muscle and various neuromuscular diseases including DMD/BMD (Becker muscular dystrophy), and its carrier is discussed.     

A benign congenital myopathy in an inbred Samaritan family.

We describe a novel form of myopathy in a mother and her two daughters from an inbred Samaritan family. The patients displayed severe neonatal hypotonia, lethargy and dysmorphic features. Motor milestones were delayed; however, the hypotonia and muscle weakness gradually improved during the first 2 years of life and independent walking was achieved by 18 months. The mother at the age of 23 years shows myopathic facies and minimal proximal weakness. Her intelligence is normal. Her muscle biopsy revealed central nuclei and disruption of the intermyofibrillary network with moth eaten and spiral fibers. Mutations in SMN, MTM1 and the myotonic dystrophy genes were excluded. We suggest this is a new benign form of congenital myopathy. Inheritance is probably autosomal recessive.