Mapping of a familial moyamoya disease gene to chromosome 3p24.2-p26

Ischemic Stroke in a Postpartum Patient: Understanding the Epidemiology, Pathogenesis, and Outcome of Moyamoya Disease

BACKGROUND

Moyamoya disease (MMD), or spontaneous occlusion of blood vessels in the circle of Willis, is a noninflammatory, nonatheromatous vasculopathy that often presents with ischemia or hemorrhage and has a tendency to affect young women. We discuss a case of a woman 7 days postpartum with new onset strokes, suspected initially to have benign angiopathy of the central nervous system (BACNS)/postpartum angiopathy versus primary CNS vasculitis. Cerebral angiography was suspicious for MMD and the patient underwent surgical revascularization.

OBJECTIVES

To review the epidemiology, presentation, diagnosis, differential diagnosis, treatment, prognosis, and postpartum maternal outcomes of MMD.

METHODS

The authors reviewed the English-language literature published between 1996 and 2004 using Medline databases. Additional articles were obtained from references described in literature obtained by the primary search.

RESULTS

MMD is characterized by severe bilateral stenosis of the distal internal carotid arteries and their first branches, with prominent collateralization. Autoantibodies relating to endothelial cell dysfunction have been studied as possible pathogenetic mechanisms. The gold standard for diagnosing MMD is digital subtraction contrast angiography (DSA). MMD-related findings on imaging studies may, at times, be mistaken for those of vasculitis. A surgical approach may need to be considered. Despite treatment, the overall prognosis of MMD is worse in adults compared with children.

CONCLUSION

Awareness of the specific features of MMD is crucial for clinical decision-making to avoid unnecessary exposure to aggressive immunosuppressive therapy. It is important for rheumatologists to consider MMD in the differential diagnosis of suspected CNS vasculitis.

Hypomelanosis of Ito and Moyamoya disease

Moyamoya disease is a cerebrovascular disease characterized by stenosis and occlusion of the arteries of the circle of Willis, with abnormal telangiectatic collateral circulation at the base of the brain. An association between moyamoya disease and neurofibromatosis 1, a neurocutanoeus disorder, is well established in the literature. However, its association with other neurocutaneous syndromes is infrequently reported. Hypomelanosis of Ito, another neurocutaneous syndrome, is characterized by macular hypopigmented skin whorls and variable neurologic involvement. Only one case study of an association between hypomelanosis of Ito and moyamoya disease has been reported in the English literature. We report a 17-year-old girl with both hypomelanosis of Ito and angiographic moyamoya disease. She presented with intractable seizures, progressive left hemiparesis, and skin manifestations of hypomelanosis of Ito. Although one might consider a coincidental association, this second case points to an association between the two disorders. Detailed neuroimaging, in particular angiography, should be considered in children with hypomelanosis of Ito and abnormal neurologic findings.

Elastosis perforans serpiginosa-like pseudoxanthoma elasticum in a child with severe Moya Moya disease

A 2-year-old girl with Moya Moya disease who had relapsing cerebrovascular strokes presented with loose skin folds, 'chicken' skin appearance and perforating elastosis serpiginosa-like lesions in the genitocrural region. Histologically, calcified material perforating the epidermis and adjacent short curled and mineralized elastic fibres suggested a variant of pseudoxanthoma elasticum (PXE). As PXE is known to be caused by various mutations in the transmembrane transporter ABCC6 gene, we hypothesized that a novel ABCC6 mutation may underlie this unique combination of PXE and elastopathic vascular damage. Therefore, the complete ABCC6 coding region of the patient and her parents was screened for genetic alterations. No bona fide disease-causing mutation of ABCC6 could be found in the child and in her parents. However, two novel allelic amino acid substitutions (Arg1273Lys and Glu1293Lys; exon 27) were found in the girl and her father, localized in close proximity to the region that codes for the functionally critical second nucleotide-binding fold of ABCC6. Although a causal involvement of these amino acid substitutions could not be proven based on this study, both heterozygote substitutions may possibly have interacted with other undetected recessive maternal ABCC6 changes in the child. To the best of our knowledge, this is the first report of an association between early-onset PXE and severe Moya Moya syndrome possibly related to ABCC6 changes.

Empty sella, hypogonadism and hypopituitarism secondary to moyamoya disease

We report the case of a young male who presented at the age of 34 years with intracranial hemorrhage due to moyamoya disease. He was later diagnosed with hypogonadism and hypopituitarism. Chromosomal evaluation revealed a normal karyotype. The results of further neuroradiological studies led to the diagnosis of empty sella syndrome.

Die Moyamoya-Erkrankung

Moyamoya disease is an idiopathic progressive vasculopathy characterized by slowly progressive narrowing involving the distal internal carotid artery and the proximal circle of Willis. Collateral vessels develop to compensate for the slowly progressive stenosis. These enlarged collaterals appear as a "puff of smoke" on angiography, which gives the disease its name. This review discusses the clinical manifestation, imaging findings, and angiographic features.

Sequence analysis and bioinformatics analysis of chromosome 17q25 in familial moyamoya disease

OBJECTS

The pathogenesis of moyamoya disease is still unknown. The present study aimed to find out the responsible genes that are located in the 17q25 locus.

METHODS

Considering the function, we selected nine genes as candidates from a total of 65 genes identified in the 9-cM region of D17S785-D17S836 in chromosome 17q25, and performed sequence analysis on the DNA samples obtained from a pedigree of familial moyamoya disease, which showed a complete linkage to the region by a haplotype analysis. Also, we attempted to identify candidate genes that have not been known but might be functionally relevant to the disease among a total of 2,100 expressed sequence tag (EST) sequences using bioinformatics techniques.

RESULTS AND CONCLUSION

The sequence analysis could detect no mutation in the nine genes. Nor could we identify a novel candidate gene by the EST analysis. Further studies using alternative approaches are warranted to clarify the pathogenesis of moyamoya disease.

A novel susceptibility locus for moyamoya disease on chromosome 8q23

Moyamoya disease (MIM 252350) is characterized by stenosis or occlusion of the terminal portions of the bilateral internal carotid arteries and by abnormal vascular networks at the base of the brain. There is a high incidence of moyamoya disease in Asia, especially in Japan. Multifactorial inheritance is estimated with lambda(s)>40. Previous linkage studies have indicated that susceptibility loci for the disease are located on chromosomes 3p, 6q, and 17q. In the present study, we searched for loci linked to the disease in 12 Japanese families using 428 microsatellite markers and found significant evidence for linkage to 8q23 [maximum LOD score (MLS) of 3.6] and suggestive evidence for linkage to 12p12 (MLS=2.3). The present study revealed a novel locus for moyamoya disease.

Moyamoya angiopathy with dolichoectatic internal carotid arteries, patent ductus arteriosus and pupillary dysfunction: a new genetic syndrome?

We report on 2 children with moyamoya angiopathy and bilateral dolichoectatic internal carotid arteries in combination with iris hypoplasia with bilateral fixed dilated pupils and a history of patent ductus arteriosus. Both were symptomatic with moyamoya angiopathy and underwent bilateral extracranial-intracranial (EC-IC) bypass operations for cerebral revascularization. This is the first report on moyamoya angiopathy and bilateral dolichoectatic internal carotid arteries with simultaneous occurrence of ocular and cardiovascular malformations. There have been descriptions of cerebral vascular abnormalities in combination with either congenital heart disease or ocular abnormalities but not with both presenting together. The combination of these separate congenital developmental defects may not be purely coincidental: we propose that the 2 probands are affected with a not yet recognized clinical syndrome of probably genetic etiology.

Is there a genetic basis for pediatric stroke?

PURPOSE OF REVIEW Childhood: stroke is more common than brain tumor, but because there is a wide spectrum in terms of etiology and most centers see only a few cases every year, there have been few large studies of genetic and environmental risk factors until recently. This review focuses on the clinical and radiologic methodology required to distinguish phenotypes in patients, and it focuses on the available data on genetic predisposition.

RECENT FINDINGS

A number of conditions with Mendelian inheritance (eg, sickle cell disease) predispose to childhood stroke, but the search for epistatic polymorphisms that explain why some but not all of these patients are affected has been hampered by our poor understanding of the pathophysiology. Emergency vascular imaging, including arteriography and venography, will almost certainly assist with the description of stroke subtypes with different genetic predisposition in these patients and in the important group of children who were completely healthy before their stroke. Environmental exposure (eg, to infection, hypoxemia, and vitamins) may play a crucial role in modifying genetic expression and must be described carefully in prospective studies.

SUMMARY

Now that much of the work on classifying stroke subtypes in children has been undertaken, international collaboration is likely to lead to identification of the genetic and environmental risk factors, and thus to primary and secondary prevention.

Serum alpha1-antitrypsin level and phenotype associated with familial moyamoya disease

BACKGROUND

Obstructive vascular lesions at the terminal portion of the internal carotid arteries are thought to be the primary and essential lesions in moyamoya disease. The etiology remains unknown. To detect possible mediators of the thickened intima of moyamoya disease, we measured serum alpha-1-antitrypsin (alpha1-AT) levels and characterized the phenotype of patients with familial moyamoya disease.

PATIENTS AND METHODS

Fifty-six individuals were examined, including 29 patients with moyamoya disease from 14 families. Serum alpha1-AT levels were analyzed by electroimmunoassay and genomic phenotype by isoelectric focusing.

RESULTS

All individuals had a normal alpha1-AT phenotype. The average serum alpha1-AT level in moyamoya disease patients was significantly higher than that of normal individuals, although both were within the normal range.

CONCLUSIONS

These findings suggest that serum alpha1-AT level may be a marker, rather than an etiologic factor, indicating the progression of moyamoya disease.

CADASIL and genetics of cerebral ischaemia

Recent advances suggest the existence of several autosomal dominantly inherited forms of cerebrovascular disorders. Mutations in diverse genes may induce direct pathological changes in intracranial vessels to cause cerebral ischaemic or haemorrhagic strokes leading to cognitive impairment and dementia. Similar pathology may also be caused by systemic vascular disease resulting from mutations and polymorphisms in genes that regulate cardiovascular physiology, blood coagulation and metabolic functions. The most common form of familial stroke appears to be CADASIL or cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. CADASIL is an arterial disease that has been linked to nucleotide substitutions and deletions in the Notch 3 gene. The pathogenesis of the disorder or how the mutations lead to cerebral infarcts and dementia is not known. However, elucidation of the microvascular pathology associated with such genetic disorders not associated with physiological risk factors for cardiovascular disease or stroke can bear much light on primary vascular mechanisms that lead to ischaemic blood flow and neuronal vulnerability.

Familial moyamoya disease in a Greek family

Moyamoya disease (M-M) is characterized by progressive obstruction of the supraclinoid portion of internal carotid arteries and the proximal middle, anterior and posterior cerebral arteries, associated with the formation of a characteristic net of collateral vessels in the basal ganglia region. Clinical manifestations in childhood include transient ischaemic attacks, seizures and multiple infarcts. Approximately 7% of M-M cases are familial. We report two affected Greek siblings with typical clinical and neuroradiological findings of M-M. Linkage analysis of the whole family was consistent with linkage to the region 3p24-26, as previously reported in other familial Japanese M-M cases.

Ngly1, a mouse gene encoding a deglycosylating enzyme implicated in proteasomal degradation: expression, genomic organization, and chromosomal mapping

In species as diverse as yeast and mammals, peptide:N-glycanase (PNG1 in yeast; Ngly1 in mouse) is believed to play a key role in the degradation of misfolded glycoproteins by the proteasome. In this study, we report the genomic organization and mRNA distribution of the mouse Ngly1. Mouse Ngly1 spans 61kb and is composed of 12 exons, the organization of which is conserved throughout vertebrates. Comparison of the mouse and human genomic sequence identifies a conserved gene structure with significant sequence similarity extending into introns. A 2.6kb Ngly1 message was detected in all mouse tissues examined, with the highest abundance in the testis. In addition, a lower molecular weight transcript of 2.4kb was detected in the testis. From analysis of dbESTs the alternative transcript of Ngly1 is predicted to be present in the human placenta. Given the key role Ngly1 plays in glycoprotein degradation, we predict that Ngly1 may be a contributing factor in "disease" susceptibility. To begin to address this question, we used radiation hybrid mapping to localize mouse Ngly1 to chromosome 14 and the human orthologue to chromosome 3 with a strong link with known genes.

Congenital vascular malformations in childhood

Congenital vascular malformations are an important group of vascular anomalies that occur very early in the pregnancy. Most of these malformations occur between the third and the seventh weeks of the embryonic development. Malformations can affect the arteries, veins, capillaries, and venous sinuses, involving an isolated vessel or a part of the vascular system. There are malformations that affect the vessel size or course, and others that show pathology of the wall anatomy of the vessel. Magnetic resonance angiography (MRA) is improving the study conditions of this pathology. Treatment of most of the vascular malformations--some of them giving clinical symptoms during adulthood--still constitutes a challenge.

Arterial strokes in children

Pediatric stroke has received special attention in the recent literature. It is now recognized as an important cause of mortality and morbidity in pediatric population. Varied and poorly specific symptomatology as well as overlapping risk factors makes the diagnosis of stroke in childhood challenging. Therapy remains controversial. The use of anticoagulation and thrombolysis in the management of acute stroke in children has not been systematically studied. In this article, we discuss the natural history, investigation, and treatment of pediatric arterial hemorrhagic and ischemic strokes.

Identification, genomic organization and mRNA expression of CRELD1, the founding member of a unique family of matricellular proteins

We have isolated and characterized a unique gene that encodes a highly conserved membrane bound extracellular protein that defines a new epidermal growth factor-related gene family. The CRELD1 (Cysteine-Rich with EGF-Like Domains 1) gene (previously known as cirrin) was cloned from a human chromosome 3 BAC. Mapping of the gene confirmed its position at chromosome 3p25.3. The gene is ubiquitously expressed in early development and later becomes more markedly expressed in the developing heart, limb buds, mandible and central nervous system. Expression persists in adulthood in most tissues. Sequence analysis suggests that this is a cell adhesion protein. The mouse orthologue was cloned and mapped to the syntenic region of mouse chromosome 6. Orthologues or homologues have also been identified for cow, Chinese hamster, Drosophila and Caenorhabditis elegans. The CRELD1 gene is deleted in the human cytogenetic disorder 3p- syndrome and is in the region of loss of heterozygosity for several types of cancer. A potential role for this protein in these disorders is discussed.

Adult moyamoya disease with peripheral artery involvement

We report the case of a young white woman in whom cerebrovascular moyamoya disease, which was associated with nonarteriosclerotic peripheral artery disease of the subclavian, iliac, and femoropopliteal arteries, was diagnosed by means of angiography. During 8 years of follow-up, the peripheral artery disease progressed, without any signs characteristic of systemic inflammation or vasculitis, leading to severe calf and arm claudication. Despite the absence of histologic confirmation, this observation strongly suggests that peripheral artery involvement may be a feature of moyamoya disease. To our knowledge, this is the first report of an association of classical cerebrovascular moyamoya disease with peripheral artery disease.

Advances in molecular genetics and pathology of cerebrovascular disorders

Progress in molecular genetics has enabled the dissection of several autosomal dominantly inherited forms of cerebrovascular disorders. Mutations in diverse genes might induce pathological changes in intracranial vessels, resulting in cerebral haemorrhages and ischaemic strokes. Such pathologies, however, might also result from systemic vascular disease caused by mutations or polymorphisms in genes that regulate cardiovascular physiology, blood coagulation, lipid metabolism and metabolic functions. Interestingly, several mutations that directly affect CNS vasculature involve genes that control inter- or intracellular signalling functions. Although highly variable phenotypes make it difficult to pinpoint the genotypes, genetic characterization of cerebrovascular disorders is valuable for understanding the pathogenesis and management of sporadic disease.

High-field magnetic resonance imaging in patients with moyamoya disease

OBJECT

The purpose of this study was to assess the utility of high-field magnetic resonance (MR) imaging as a quantitative tool for estimating cerebral circulation in patients with moyamoya disease.

METHODS

Eighteen patients with moyamoya disease who were scheduled to undergo revascularization surgery and 100 healthy volunteers were examined using T2-reversed MR imaging performed using a 3-tesla system. Ten of the 18 patients underwent a second study between 1 year and 3 years after revascularization. Magnetic resonance images obtained in the patients with moyamoya disease were statistically analyzed and compared with those obtained in healthy volunteers. The MR imaging findings were also correlated with results of single-photon emission computerized tomography and conventional cerebral angiography studies. Transverse lines in the white matter (medullary streaks) were observed in almost all persons. In healthy volunteers, the diameter sizes of the medullary streaks increased significantly with age (p < 0.001). Multiple logistic regression analysis revealed that age-adjusted medullary streak diameters were significantly larger in patients with moyamoya disease (p < 0.001). Diameter sizes also increased significantly with the increased severity of cerebral hypoperfusion (p < 0.001) and a higher angiographically determined stage of the disease (p < 0.001). Diameter sizes decreased significantly after surgery (p < 0.001).

CONCLUSIONS

The increases in medullary streak diameters observed in patients with moyamoya disease appear to represent vessels dilated due to cerebral hypoperfusion. High-field T2-reversed MR imaging is useful in estimating cerebral circulation in patients with moyamoya disease.

Molecular cloning of PalBH, a mammalian homologue of the Aspergillus atypical calpain PalB

A mammalian homologue of the Aspergillus atypical calpain PalB, PalBH, was identified and its cDNA sequences were determined in human and mouse. The PalBH mRNA was expressed nearly ubiquitously throughout mammalian tissues. When expressed in COS cells, PalBH was enriched in the nucleus, suggesting its role is distinct from that of conventional calpains.

Moyamoya disease

Moyamoya disease is a specific chronic cerebrovascular occlusive disease first reported by Japanese surgeons in 1957. The disease is characterized by stenosis or occlusion of the terminal portions of the bilateral internal carotid arteries and abnormal vascular network in the vicinity of the arterial occlusion. It may cause ischemic attacks or cerebral infarction, which is more frequent in children than in adults. In adults, cerebral hemorrhage may occur. The disease is distributed in all age groups, but the highest peak is in childhood at less than 10 years of age. The characteristic histopathologic features of the steno-occlusive arteries are fibrocellular thickening of the intima containing proliferated smooth muscle cells and prominently tortuous and often duplicated internal elastic lamina. There is usually no atheromatous plaque in the arterial wall. Etiology of the disease is still unknown; however, multifactorial inheritance is considered possible because of a higher incidence of the disease in Japanese and Koreans and approximately 10% of familial occurrence among the Japanese. Recent genetic studies suggest some responsible genetic foci in chromosomes 3, 6 and 17.

Basal meningoencephalocele, anomaly of optic disc and panhypopituitarism in association with moyamoya disease

Basal meningoencephalocele is frequently associated with midfacial anomaly, optic disc anomaly, brain anomaly, cerebrospinal fluid rhinorrhea, chiasma syndrome, and endocrinologic disturbance. The combination of basal meningoencephalocele and moyamoya disease is extremely rare. A 29-year-old man had basal meningoencephalocele (transsphenoidal type), anomaly of the optic disc (morning glory syndrome), panhypopituitarism and moyamoya disease. The patient was treated by hormone replacement, but surgical intervention was not required. Basal meningoencephalocele and moyamoya disease are a possible combination of the diseases.

Risk factors for arterial ischemic stroke in children

Since early recurrence occurs in at least 10% of patients presenting with their first stroke in childhood in the reported series, the search for modifiable risk factors should be a priority. Risk factors for stroke in adults include hypertension, diabetes, and smoking, as well as cardiac disease and sickle cell anemia; asymptomatic cerebrovascular disease and transient ischemic events may predict stroke in this age group. The investigation of a child with a stroke has traditionally focused on finding a single cause rather than looking for risk factors to which the patient may be exposed life long. Approximately half of children presenting with stroke have a known predisposing condition, but some have unexpected pathologies such as primary cerebrovascular disease associated with congenital heart anomalies, or may have modifiable risk factors such as hypertension associated with sickle cell disease. The literature on children presenting with initially unexplained (cryptogenic) stroke suggests that there is a daunting list of possible causes, but since the series have mainly been small, it has been difficult to evaluate the relative importance of the reported associations. This paper reviews the literature on congenital, genetic, and acquired risk factors for stroke in childhood, and includes data from the large series of patients seen at Great Ormond Street Hospital over the past 10 years. The majority have arteriographic abnormalities and there is little evidence for asymptomatic cardiac disease. Genetic predisposition, trauma, infection, and nutritional deficiencies appear to be important, although case-control studies will be required to prove causation. Appropriate screening for modifiable risk factors may lead to prevention of recurrence in some patients. In the long term, an understanding of the multiple etiologies of childhood cerebrovascular disease and ischemic stroke may lead to primary prevention in this age group, and perhaps in adults.

Rational approach to treatment of moyamoya disease in childhood

Early diagnosis and treatment of moyamoya disease in children is essential to minimize residual mental and physiologic deficits. Current treatment of childhood moyamoya disease in Japan, preoperative evaluation of perfusion reserve as a surgical indication, and the role of noninvasive follow-up by magnetic resonance angiography are reported. Approximately 20% of children with definite moyamoya disease were observed or treated medically. Among surgical procedures, single indirect bypass surgery was used in approximately 30% of all patients; combinations of direct and indirect bypass surgery, 20%; and multiple-indirect bypass surgery, 18%. Both adequate understanding of the primary condition and determination of optimal treatment, including specific operative procedures, required evaluation of cerebral circulation and metabolism. Surgical indications included reduced perfusion reserve in affected brain by positron emission tomography or single photon emission tomography with administration of acetazolamide or a CO2 load. Postoperative improvements of cerebral perfusion reserve show better correlation with disappearance of ischemic attacks than does angiographically demonstrated collateral formation. Follow-up evaluation with magnetic resonance angiography has advantages over conventional angiography because it is noninvasive and avoids general anesthesia.

Linkage of familial moyamoya disease (spontaneous occlusion of the circle of Willis) to chromosome 17q25

BACKGROUND AND PURPOSE

Moyamoya disease is a cerebrovascular disease of unknown cause that mainly affects Japanese children. The incidence of familial occurrence accounts for 9% of cases. The characteristic lesions of moyamoya disease are occasionally seen in neurofibromatosis type 1, of which the causative gene (NF1) has been assigned to chromosome 17q11.2.

METHODS

To determine whether a gene related to moyamoya disease is located on chromosome 17, we conducted microsatellite linkage analyses on 24 families containing 56 patients with moyamoya disease. Leukocyte DNA extracted from the family members was subjected to polymerase chain reaction for a total of 22 microsatellite markers on chromosome 17. The amplified polymerase chain reaction fragments were analyzed with GeneScan on an automated sequencer.

RESULTS

Two-point linkage analysis gave a maximum log(10) odds (LOD) score of 3.11 at the recombination fraction of 0.00 for the marker at locus D17S939. The affected pedigree member method also showed a significantly low P value (<1. 0x10(-5)) for the 5 adjacent markers at 17q25. Multipoint linkage analysis also indicated that the disease gene is contained within the 9-cM region of D17S785 to D17S836, with a maximum LOD score of 4. 58.

CONCLUSIONS

A gene for familial moyamoya disease is located on chromosome 17q25.

Linkage analysis of moyamoya disease on chromosome 6

Genetic factors have been suggested to contribute to the etiology of moyamoya disease. The authors have previously reported an association between moyamoya disease and several alleles for human leukocyte antigens (HLA). To further specify the genetic component of moyamoya disease, a linkage study of moyamoya disease using markers on chromosome 6, where the HLA gene is located, was performed. The 15 microsatellite markers of chromosome 6 were studied in 20 affected sibling pairs. From an identical-by-descent analysis of these markers, an allele with possible linkage to moyamoya disease was identified. Sharing of the allele among affected members in 19 families was investigated, considering the haplotype. The marker, D6S441, might be linked to moyamoya disease. Considering the haplotype, the allele was shared among the affected members in 16 (82%) of the 19 families, but not in two others. In one family, sharing of the allele could not be determined because of low heterozygosity. Further studies are necessary to clarify multiple genetic factors that are definitely linked with moyamoya disease.

Identification of a novel LIM domain gene, LMCD1, and chromosomal localization in human and mouse

A new human LIM domain gene LMCD1 was identified from RT-PCR products, and partial sequencing of two expressed sequence tag clones flanking the assembled cDNA contig revealed a 1743-bp full-length cDNA with 1098-bp open reading frame. The coding sequence of the putative protein is 57.6% identical to murine testin 1 gene (Tes1), whereas the predicted 365-amino-acid protein is 49.5% identical to the mouse Tes1 protein. The predicted LMCD1 protein contains a novel cysteine-rich domain residing in the amino-terminal region and two LIM domains with regular spacing in the carboxy-terminal region. Northern blot analysis indicated expression of the 1.7-kb transcript in many tissues, with highest abundance in skeletal muscle. Radiation hybrid mapping localized human LMCD1 to the telomeric region of chromosome 3p, and genetic mapping assigned the mouse Lmcd1 locus to the central region of chromosome 6.