Increase in fetal breech presentation in female carriers of Duchenne muscular dystrophy.

Female carriers of Duchenne muscular dystrophy (DMD) may demonstrate elevated serum creatine kinase (CK) and reduction of muscle dystrophin in all muscle types. We hypothesized that decreased dystrophin in uterine or pelvic girdle musculature might affect the obstetrical performance of females heterozygous for a dystrophin mutation. We reviewed the outcome of 34 deliveries resulting in 35 children from 13 women who were mothers of males attending a muscular dystrophy clinic. Obstetrical performance was examined retrospectively by chart review and patient contact. Of 35 children, 6 (17%) were delivered in the breech position, which is a fivefold increase above the national standards for term pregnancies. Of the six infants with breech presentation, two were males affected with DMD, one was a female heterozygote, one was a male who died perinatally, and the carrier status of the other two females is unknown. Most DMD affected males (12/14) were delivered in the vertex position. Thus, it is likely that maternal, rather than fetal, muscle weakness was the significant factor in determination of fetal position at term. We speculate that subtle changes in uterine or pelvic girdle muscle tone may contribute to a higher rate of fetal breech position in carriers of the DMD gene.

The concomitant use of dystrophin and utrophin/dystrophin related protein antibodies to reduce misdiagnosis of Duchenne/Becker muscular dystrophy.

Antibodies to dystrophin have increased accuracy in the diagnosis of Duchenne/Becker muscular dystrophy (D/BMD). Both typical and 'atypical' presentations of this disease can be confirmed by demonstrating qualitative and quantitative defects in the expression of dystrophin protein. However, owing to the propensity for dystrophin degradation in vitro, caution needs to be applied while performing and interpreting antibody-based dystrophin analysis. Here we identify two cases where in vitro protein degradation caused diagnostic confusion. We demonstrate the use of utrophin/dystrophin related protein (DRP) as sensitive control for sample degradation, since it is more labile than dystrophin. We suggest that the concomitant or sequential usage of antibodies specific for dystrophin along with utrophin/DRP can help reduce the misdiagnosis of D/BMD.

Congenital muscular dystrophy associated with merosin deficiency.

"Classic" congenital muscular dystrophy is a heterogeneous group of disorders, characterized by early-onset muscle weakness and hypotonia, absence of overt cerebral or ocular symptoms, and muscle pathology consistent with a dystrophic process. A subset of patients with congenital muscular dystrophy have recently been found to be deficient in the extracellular matrix protein merosin. Consequently, we reviewed the clinical, pathologic, and immunohistochemical features of 12 patients (six males and six females) with classic congenital muscular dystrophy who have been seen at the Children's Hospital, Boston, over the past 15 years. There was marked clinical heterogeneity within this patient population, with age of independent ambulation ranging from 13 months to 6 years. Immunocytochemical analysis using antibodies to merosin, dystrophin, 43-kDa dystroglycan, adhalin, and laminin was normal in 11 of 12 patients. One patient had markedly abnormal staining for merosin; the majority of fibers were negative, although occasional fibers demonstrated patchy staining. Immunoblot analysis in this patient demonstrated markedly reduced levels of merosin (< 10% compared to controls and other patient), of apparently normal size. Clinically, this patient could be differentiated from the others by a marked elevation of serum creatine kinase (> 1000 U/L) and the presence of early white-matter changes on magnetic resonance imaging. The results of this study support the observation that abnormalities of merosin are present in a subgroup of patients with classic congenital muscular dystrophy. Although marked elevation of serum creatine kinase and white-matter changes on magnetic resonance imaging may serve to distinguish these patients from other patients with congenital muscular dystrophy, there remains a large proportion of patients in whom the underlying pathogenesis remains to be elucidated.

Cognitive dysfunction as the major presenting feature of Becker's muscular dystrophy.

We report four patients, currently aged 15, 17, 19, and 42 years, with X-linked dystrophinopathy who presented with mental retardation (IQ range, 60-68) and psychiatric disturbance in the absence of muscle weakness. All patients had elevated serum creatine kinase and dystrophic changes on muscle biopsy. There were alterations in the size and abundance of dystrophin on immunohistochemistry and immunoblotting in all cases, consistent with a molecular diagnosis of Becker's muscular dystrophy. Two patients had deletions of the dystrophin gene on DNA analysis. These findings suggest that Becker's muscular dystrophy may be associated with a predominantly neuropsychiatric presentation and that dystrophinopathy should be considered in the differential diagnosis of unexplained cognitive or psychiatric disturbance in males. Serum creatine kinase may provide an adequate screening test in this clinical situation.

Mapping a gene for congenital fibrosis of the extraocular muscles to the centromeric region of chromosome 12.

Congenital Fibrosis of the Extraocular Muscles (CFEOM) is an autosomal dominant, ocular disorder characterized by congenital, nonprogressive, bilateral ptosis and external ophthalmoplegia. The pathophysiology of this disorder is unknown and it is unclear if it has a primary neurogenic or myopathic etiology. We report linkage of this disorder, in two unrelated families, to markers in the pericentromeric region of human chromosome 12. D12S59 does not recombine with the disease giving a two-point lod score of 12.5 (theta = 0.00). D12S87 and D12S85 flank the CFEOM locus with two-point lod scores of 8.9 (theta = 0.03) and 5.4 (theta = 0.03) respectively, defining a region of 8 cM. These data establish a map location for CFEOM and demonstrate that this may be a genetically homogeneous disorder.

Progressive juvenile segmental spinal muscular atrophy.

Juvenile segmental spinal muscular atrophy (JSSMA) typically involves the distal upper extremities and follows a benign course over 2-4 years then stabilizes. We report 2 males who presented in their teens with insidious distal upper extremity atrophy and weakness as in typical JSSMA but who then progressed to involvement of the lower extremities and hyperreflexia. There was no sensory loss. Electromyography and muscle biopsy demonstrated features consistent with localized anterior horn cell dysfunction. These patients are noteworthy because they demonstrate that some patients with JSSMA also may have involvement of the lower limbs several years after initial presentation. Progressive JSSMA may be categorized in the clinical spectrum between the spinal muscular atrophies and amyotrophic lateral sclerosis.

Prediction of dystrophin phenotype by DNA analysis in Duchenne/Becker muscular dystrophy.

Allele-specific molecular diagnosis of Duchenne and Becker muscular dystrophies (DMD and BMD) has been largely dependent upon muscle biopsy for dystrophin protein assay. We performed lymphocyte DNA mutation analysis by polymerase chain reaction on 14 boys presenting with a clinical picture compatible with DMD or BMD. DNA analysis revealed that 12 of 14 boys had a deletion of the dystrophin gene, thus establishing the diagnosis of DMD/BMD. Furthermore, genotypes for 9 of 12 deletion patients permitted prediction of the specific allelic disorder (i.e., DMD or BMD). Subsequent dystrophin testing confirmed all of the DNA-based diagnoses. We propose that DNA mutation analysis be included in the initial evaluation of patients suspected of having DMD/BMD, thus potentially eliminating the need for muscle biopsy in the majority of patients.

Childhood onset oculopharyngeal muscular dystrophy.

Oculopharyngeal muscular dystrophy is an inherited disorder, usually autosomal dominant, which typically becomes symptomatic during the fifth decade of life with slowly progressive ptosis and dysphagia; childhood onset has not been reported. A 13-year-old female of French-Canadian descent developed nasal speech and strabismus at 5 years of age; there was no family history of neuromuscular disease. Ptosis and mild facial and proximal muscle weakness were present by 9 years of age. Over the next 4 years, the patient developed dysphagia, palatal paralysis, weight loss, decreased ocular motility, scoliosis, shortness of breath, and obstructive apnea. Tracheostomy and gastrostomy were required. Creatine kinase and repetitive facial nerve stimulation were normal. Edrophonium testing was negative and electromyography revealed myopathic motor units in the iliopsoas muscle. A preponderance of type I fibers and scattered atrophic and angulated muscle fibers were present in 3 muscle biopsies. The clinical presentation and findings are consistent with childhood onset oculopharyngeal muscular dystrophy.

Fine structure of the nigrostriatal anlage in fetal rat brain by immunocytochemical localization of tyrosine hydroxylase.

The developmental morphology and synaptic associations of neurons in the nigrostriatal anlage are examined by the electron microscopic immunocytochemical localization of tyrosine hydroxylase at embryonic (E) day 13.5 and 14.5 in rat brain. At E 13.5, immunoreactivity for the enzyme is localized throughout the cytoplasm of neuronal perikarya and processes including somatic, dendritic, and axonal growth cones. The cytoplasmic organelles in perikarya include primarily ribonucleic-protein particles, mitochondria and an immature Golgi apparatus. At E 14.5, the tyrosine hydroxylase labeled processes are detected in the lateral hypothalamus and ventrolateral caudate-putamen. The axonal processes showing immunoreactivity in the ventral mesencephalon and more rostral portions of the nigrostriatal bundle are frequently attached to unlabeled neurites by puncta adherentia. In the hypothalamus and caudate-putamen presumably transient synaptic junctions are also detected between the labeled axons and unlabeled neurons. The immature morphological features of neurons showing immunoreactivity for tyrosine hydroxylase thus indicate, that the biochemical differentiation of the nigrostriatal neurons precedes complete cytological differentiation.

Light-microscopic immunocytochemical localization of tyrosine hydroxylase in prenatal rat brain. I. Early ontogeny.

The immunocytochemical localization of tyrosine hydroxylase is examined during early ontogeny in the fetal rat brain in order to determine the age of first detection and subsequent cellular localization of the enzyme and the developmental characteristics of the immature catecholaminergic neurons. Fetal atlases of the tyrosine hydroxylase-labeled neurons are presented at embryonic day (E) 12.5, 13.5, and 14.5. Tyrosine hydroxylase is first detected immunocytochemically at E 12.5. At this stage, the labeled neurons have completed final mitosis, but are still migrating and are cytologically immature. Tyrosine hydroxylase can also be detected in axons and axonal growth cones at this stage of development. The age of first immunocytochemical detection of the enzyme precedes the demonstration of catecholamine fluorescence by 1 to 2 days in certain nuclear groups. At later stages of development (E 13.5 and E 14.5), the major groups of perikarya and processes labeled for tyrosine hydroxylase have a distribution similar to that previously described by catecholamine fluorescence. At E 14.5, the perikarya undergo considerable changes in their cytology and exhibit the first dendrites immunocytochemically labeled for the enzyme. The first terminal fields are also detected in the rudimentary caudate-putamen at this stage.

Light-microscopic immunocytochemical localization of tyrosine hydroxylase in prenatal rat brain. II. Late ontogeny.

The immunocytochemical localization of tyrosine hydroxylase is examined at embryonic (E) days 18 and 21 in rat brain in order to determine changes in the distribution and cytology of neurons showing immunoreactivity for the enzyme during late prenatal development. As compared with earlier stages of development, the distribution and morphology of the tyrosine hydroxylase-containing neurons at E18 and E21 more closely resemble catecholaminergic neurons in the adult brain. The changes occurring from the early to the late prenatal stages of development appear to be the result of an increase in number of cells and continued aggregation and migration of the labeled neurons. The major differences in the distribution of labeled perikarya between E18 and E21 are in the olfactory bulb and cerebral cortex. In the olfactory bulb, tyrosine hydroxylase-containing neurons are not detected until E21. In contrast in the cerebral cortex, a few neurons are transiently labeled for the enzyme at E18, but are not detected at E21 and have not been reported in the adult brain. The most striking change in the tyrosine-hydroxylase labeled structures in the late prenatal period is the increase in detectable immunoreactivity in bundles of axons and in terminal aborizations. The orderly appearance of tyrosine hydroxylase-labeled axons in the neostriatum and cortex are discussed in relation to the formation of these two contrasting regions innervated by catecholaminergic neurons.

Immunocytochemical localization of tyrosine hydroxylase in the human fetal nervous system.

The peroxidase-antiperoxidase (PAP) technique is used to determine the cellular localization of tyrosine hydroxylase in the human fetal nervous system. Antiserum to trypsin-treated tyrosine hydroxylase from the bovine adrenal medulla can be detected immunocytochemically in peripheral sympathetic neurons in the 8-mm (5-week) fetus, but can not be detected in the central nervous system until later stages of development. The cytological features and distribution of the neuronal perikarya and processes labeled for the enzyme are similar to those of the catecholaminergic neurons previously identified by histofluorescence. These findings indicate that specific neurons in the human fetus have at least one of the enzymes necessary for the biosynthesis of catecholamines and that cross-species reactivity exists between antiserum produced to the bovine tyrosine hydroxylase and human tissues.

Catecholamine biosynthetic enzymes are expressed in replicating cells of the peripheral but not the central nervous system.

We sought to determine whether the precursors of catecholamine-containing neurons in the developing peripheral and central nervous systems of chickens and rats express the biosynthetic enzymes tyrosine hydroxylase [THase; tyrosine 3-monooxygenase; L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] or dopamine beta-hydroxylase [DBHase; 3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (beta-hydroxylating), EC 1.14.17.1], prior to the time they withdraw from the cell cycle. Chicken embryos (stages 26-27) were injected with [3H-thymidine and 4 hr later were prepared for the simultaneous demonstration of radioautographically labeled nuclei in immunoreactive THase cells. The brains and sympathetic chains of rat fetuses (days E12-E14), exposed for 2 hr to [3H]thymidine, were treated similarly except that peripheral tissues were stained with a specific antibody to DBHase as well as anti-THase. In the peripheral nervous system of both chicken and rat, nuclei of THase-containing cells were radioautographically labeled. DBHase-containing cells in the peripheral nervous system of rats were also labeled and thus are noradrenergic. THase was localized in cells of the brain of the same rat fetuses beginning on day E12 (no THase was detected on day E11 or E11.5) in the mantle layer of the ventral mesencephalic and rostrolateral rhombocephalic cellular groups; however. THase-containing cells in the central nervous system did not incorporate [3H]thymidine. We conclude that, during development, the adrenergic neuronal precursors of the peripheral nervous system but not of the central, have the capacity to synthesize catecholamines before they withdraw from the cell cycle. Differences in the maturation of peripheral and central neurons may be related to differences in their embryological origin.