Mandibuloacral Dysplasia Research Articles

Mandibuloacral Dysplasia Caused byLMNAMutations and Uniparental Disomy

Mandibuloacral dysplasia (MAD) is a rare autosomal recessive disorder characterized by postnatal growth retardation, craniofacial anomalies, skeletal malformations, and mottled cutaneous pigmentation. Hutchinson-Gilford Progeria Syndrome (HGPS) is characterized by the clinical features of accelerated aging in childhood. Both MAD and HGPS can be caused by mutations in the LMNA gene. In this study, we describe a 2-year-old boy with overlapping features of MAD and HGPS. Mutation analysis of the LMNA gene revealed a homozygous missense change, p.M540T, while only the mother carries the mutation. Uniparental disomy (UPD) analysis for chromosome 1 showed the presence of maternal UPD. Markers in the 1q21.3–q22 region flanking the LMNA locus were isodisomic, while markers in the short arm and distal 1q region were heterodisomic. These results suggest that nondisjunction in maternal meiosis followed by loss of the paternal chromosome 1 during trisomy rescue might result in the UPD1 and homozygosity for the p.M540T mutation observed in this patient.

New ZMPSTE24 (FACE1) mutations in patients affected with restrictive dermopathy or related progeroid syndromes and mutation update.

Restrictive dermopathy (RD) is a rare and extremely severe congenital genodermatosis, characterized by a tight rigid skin with erosions at flexure sites, multiple joint contractures, low bone density and pulmonary insufficiency generally leading to death in the perinatal period. RD is caused in most patients by compound heterozygous or homozygous ZMPSTE24 null mutations. This gene encodes a metalloprotease specifically involved in lamin A post-translational processing. Here, we report a total of 16 families for whom diagnosis and molecular defects were clearly established. Among them, we report seven new ZMPSTE24 mutations, identified in classical RD or Mandibulo-acral dysplasia (MAD) affected patients. We also report nine families with one or two affected children carrying the common, homozygous thymine insertion in exon 9 and demonstrate the lack of a founder effect. In addition, we describe several new ZMPSTE24 variants identified in unaffected controls or in patients affected with non-classical progeroid syndromes. In addition, this mutation update includes a comprehensive search of the literature on previously described ZMPSTE24 mutations and associated phenotypes. Our comprehensive analysis of the molecular pathology supported the general rule: complete loss-of-function of ZMPSTE24 leads to RD, whereas other less severe phenotypes are associated with at least one haploinsufficient allele.

Precautions in using a perforator free flap to treat mandibuloacral dysplasia-a case report

Mandibuloacral dysplasia (MAD) is a rare form of inherited lipodystrophy. The type B pattern is characterized by a generalized absence of subcutaneous tissues. There is also a deficiency of perivascular adiposity that makes the dissection not only of perforators and their source vessels difficult, but the recipient site vasculature as well. Perforator flaps in the MAD patient by definition will never be bulky, and instead a challenge in every respect as the perforators are extremely diminutive and therefore fragile. However, if a large, thin flap with a long pedicle of reasonable caliber is indicated, the attributes of a perforator flap may still be indicated as demonstrated in this case report for a recalcitrant heel pressure sore that had failed the usual conservative medical treatment.

Transcatheter aortic valve implantation in a very young patient

Transcatheter aortic valve implantation (TAVI) is the standard treatment for patients with severe aortic stenosis and unacceptable surgical risk. These are usually elderly patients with multiple comorbidities.We report the case of a 20-year-old man with mandibuloacral dysplasia, an extremely rare premature aging syndrome, and severe symptomatic aortic stenosis, referred to our center for TAVI after being considered unsuitable for surgical aortic valve replacement. TAVI by a transfemoral approach was performed successfully. Severe acute respiratory failure that did not respond to optimal conventional treatment led us to employ venovenous extracorporeal membrane oxygenation. The device was removed after 10 days, and the patient was discharged home 27 days later. At one-year follow-up he is in NYHA class I with full functional autonomy. To the best of our knowledge, this is the youngest patient to undergo TAVI reported in the literature.

Implantação percutânea de válvula aórtica em doente muito jovem

Transcatheter aortic valve implantation (TAVI) is the standard treatment for patients with severe aortic stenosis and unacceptable surgical risk. These are usually elderly patients with multiple comorbidities.We report the case of a 20-year-old man with mandibuloacral dysplasia, an extremely rare premature ageing syndrome, and severe symptomatic aortic stenosis, referred to our center for TAVI after being considered unsuitable for surgical aortic valve replacement. TAVI by a transfemoral approach was performed successfully. Severe acute respiratory failure that did not respond to optimal conventional treatment led us to employ venovenous extracorporeal membrane oxygenation. The device was removed after 10 days, and the patient was discharged home 27 days later. At one-year follow-up he is in NYHA class I with full functional autonomy. To the best of our knowledge, this is the youngest patient to undergo TAVI reported in the literature.

Progeroid laminopathy with restrictive dermopathy-like features caused by an isodisomic LMNA mutation p.R435C

The clinical course of a female patient affected by a progeroid syndrome with Restrictive Dermopathy (RD)-like features was followed up. Besides missing hairiness, stagnating weight and growth, RD-like features including progressive skin swelling and solidification, acrocontractures, osteolysis and muscular hypotension were observed until the patient died at the age of 11 months. A homozygousLMNA mutation c.1303C>T (p.R435C) was found by Sanger sequencing. Haplotyping revealed a partial uniparental disomy of chromosome 1 (1q21.3 to 1q23.1) including the LMNA gene. In contrast to reported RD patients with LMNA mutations, LMNA p.R435C is not located at the cleavage site necessary for processing of prelamin A by ZMPSTE24 and leads to a distinct phenotype combining clinical features of Restrictive Dermopathy, Mandibuloacral Dysplasia and Hutchinson-Gilford Progeria. Functionally, LMNA p.R435C is associated with increasing DNA double strand breaks and decreased recruitment of P53 binding protein 1 (53BP1) to DNA-damage sites indicating delayed DNA repair. The follow-up of the complete clinical course in the patient combined with functional studies showed for the first time that a progressive loss of lamin A rather than abnormal accumulation of prelamin A species could be a pathophysiological mechanism in progeroid laminopathies, which leads to DNA repair deficiency accompanied by advancing tissue degeneration.

Hutchinson-Gilford progeria syndrome accompanied by severe skeletal abnormalities in two Chinese siblings: two case reports

IntroductionHutchinson-Gilford progeria syndrome is a rare pediatric genetic syndrome with an incidence of one per eight million live births. The disorder is characterized by premature aging, generally leading to death due to myocardial infarction or stroke at approximately 13.4 years of age. The genetic diagnosis and special clinical manifestation in two Han Chinese siblings observed at our clinic for genetic counseling are described in this report. We screened the LMNA gene in these two siblings as well as in their unaffected parents. A homozygous mutation R527C was identified in the affected siblings, and both parents were heterozygous for this variant.Case presentationIn case 1, the elder 10-year-old female sibling showed the classic physical and radiological changes of Hutchinson-Gilford progeria syndrome in addition to a considerable overlap with the phenotype of mandibuloacral dysplasia.In case 2, the younger male sibling had begun to show some early physical changes at age six months.ConclusionThe phenotypic findings in the patients we describe here widen the clinical spectrum of Hutchinson-Gilford progeria syndrome symptoms, providing further recognition of the phenotypic range of LMNA-associated diseases.

An inherited LMNA gene mutation in atypical Progeria syndrome

Hutchinson-Gilford Progeria syndrome (HGPS) is a rare genetic disorder, characterized by several clinical features that begin in early childhood, recalling an accelerated aging process. The diagnosis of HGPS is based on the recognition of common clinical features and detection of the recurrent heterozygous c.1824C>T (p.Gly608Gly) mutation within exon 11 in the Lamin A/C encoding gene (LMNA). Besides "typical HGPS," several "atypical progeria" syndromes (APS) have been described, in a clinical spectrum ranging from mandibuloacral dysplasia to atypical Werner syndrome. These patients's clinical features include progeroid manifestations, such as short stature, prominent nose, premature graying of hair, partial alopecia, skin atrophy, lipodystrophy, skeletal anomalies, such as mandibular hypoplasia and acroosteolyses, and in some cases severe atherosclerosis with metabolic complications. APS are due in several cases to de novo heterozygous LMNA mutations other than the p.Gly608Gly, or due to homozygous BAFN1 mutations in Nestor-Guillermo Progeria syndrome (NGPS). We report here and discuss the observation of a non-consanguineous Moroccan patient presenting with atypical progeria. The molecular studies showed the heterozygous mutation c.412G>A (p.Glu138Lys) of the LMNA gene. This mutation, previously reported as a de novo mutation, was inherited from the apparently healthy father who showed a somatic cell mosaicism.

Familial partial lipodystrophy, mandibuloacral dysplasia and restrictive dermopathy feature barrier-to-autointegration factor (BAF) nuclear redistribution

Prelamin A processing impairment is a common feature of a restricted group of rare genetic alterations/disorders associated with a wide range of clinical phenotypes. Changes in histone posttranslational modifications, alterations in non-histone chromatin proteins and chromatin disorganization have been specifically linked to impairment of specific, distinct prelamin A processing steps, but the molecular mechanism involved in these processes is not yet understood . In this study, we show that the accumulation of wild-type prelamin A detected in restrictive dermopathy (RD), as well as the accumulation of mutated forms of prelamin A identified in familial partial lipodystrophy (FPLD) and mandibuloacral dysplasia (MADA), affect the nuclear localization of barrier-to-autointegration factor (BAF), a protein able to link lamin A precursor to chromatin remodeling functions. Our findings, in accordance with previously described results, support the hypothesis of a prelamin A involvement in BAF nuclear recruitment and suggest BAF-prelamin A complex as a protein platform usually activated in prelamin A-accumulating diseases. Finally, we demonstrate the involvement of the inner nuclear membrane protein emerin in the proper localization of BAF-prelamin A complex.

Human ZMPSTE24 disease mutations: residual proteolytic activity correlates with disease severity

The zinc metalloprotease ZMPSTE24 plays a critical role in nuclear lamin biology by cleaving the prenylated and carboxylmethylated 15-amino acid tail from the C-terminus of prelamin A to yield mature lamin A. A defect in this proteolytic event, caused by a mutation in the lamin A gene (LMNA) that eliminates the ZMPSTE24 cleavage site, underlies the premature aging disease Hutchinson-Gilford Progeria Syndrome (HGPS). Likewise, mutations in the ZMPSTE24 gene that result in decreased enzyme function cause a spectrum of diseases that share certain features of premature aging. Twenty human ZMPSTE24 alleles have been identified that are associated with three disease categories of increasing severity: mandibuloacral dysplasia type B (MAD-B), severe progeria (atypical 'HGPS') and restrictive dermopathy (RD). To determine whether a correlation exists between decreasing ZMPSTE24 protease activity and increasing disease severity, we expressed mutant alleles of ZMPSTE24 in yeast and optimized in vivo yeast mating assays to directly compare the activity of alleles associated with each disease category. We also measured the activity of yeast crude membranes containing the ZMPSTE24 mutant proteins in vitro. We determined that, in general, the residual activity of ZMPSTE24 patient alleles correlates with disease severity. Complete loss-of-function alleles are associated with RD, whereas retention of partial, measureable activity results in MAD-B or severe progeria. Importantly, our assays can discriminate small differences in activity among the mutants, confirming that the methods presented here will be useful for characterizing any new ZMPSTE24 mutations that are discovered.

Altered chromatin organization and SUN2 localization in mandibuloacral dysplasia are rescued by drug treatment

Mandibuloacral dysplasia type A (MADA) is a rare laminopathy characterized by growth retardation, craniofacial anomalies, bone resorption at specific sites including clavicles, phalanges and mandibula, mottled cutaneous pigmentation, skin rigidity, partial lipodystrophy, and insulin resistance. The disorder is caused by recessive mutations of the LMNA gene encoding for A-type lamins. The molecular feature of MADA consists in the accumulation of the unprocessed lamin A precursor, which is detected at the nuclear rim and in intranuclear aggregates. Here, we report the characterization of prelamin A post-translational modifications in MADA cells that induce alterations in the chromatin arrangement and dislocation of nuclear envelope-associated proteins involved in correct nucleo-cytoskeleton relationships. We show that protein post-translational modifications change depending on the passage number, suggesting the onset of a feedback mechanism. Moreover, we show that treatment of MADA cells with the farnesyltransferase inhibitors is effective in the recovery of the chromatin phenotype, altered in MADA, provided that the cells are at low passage number, while at high passage number, the treatment results ineffective. Moreover, the distribution of the lamin A interaction partner SUN2, a constituent of the nuclear envelope, is altered by MADA mutations, as argued by the formation of a highly disorganized lattice. Treatment with statins partially rescues proper SUN2 organization, indicating that its alteration is caused by farnesylated prelamin A accumulation. Given the major role of SUN1 and SUN2 in the nucleo-cytoskeleton interactions and in regulation of nuclear positioning in differentiating cells, we hypothesise that mechanisms regulating nuclear membrane–centrosome interplay and nuclear movement may be affected in MADA fibroblasts.Electronic supplementary materialThe online version of this article (doi:10.1007/s00418-012-0977-5) contains supplementary material, which is available to authorized users.

The empowerment of translational research: lessons from laminopathies

The need for a collaborative approach to complex inherited diseases collectively referred to as laminopathies, encouraged Italian researchers, geneticists, physicians and patients to join in the Italian Network for Laminopathies, in 2009. Here, we highlight the advantages and added value of such a multidisciplinary effort to understand pathogenesis, clinical aspects and try to find a cure for Emery-Dreifuss muscular dystrophy, Mandibuloacral dysplasia, Hutchinson-Gilford Progeria and forms of lamin-linked cardiomyopathy, neuropathy and lipodystrophy.

A novel homozygous p.Arg527Leu LMNA mutation in two unrelated Egyptian families causes overlapping mandibuloacral dysplasia and progeria syndrome

Mandibuloacral dysplasia (MAD) is a rare disease resulting from a mutation of LMNA gene encoding lamins A and C. The most common mutation associated with this disease is a homozygous arginine 527 replacement by histidine. Three female patients originating from two unrelated families from Northeast Egypt were examined. Their growth was retarded; they had microcephaly, widened cranial sutures, prominent eyes and cheeks, micrognathia, dental crowding, hypoplastic mandible, acro-osteolysis of distal phalanges, and joint contractures. In addition, they presented some progeroid features, such as pinched nose, premature loss of teeth, loss of hair, scleroderma-like skin atrophy, spine rigidity, and waddling gait. The clinical presentation of the disease varied between the patient originating from Family 1 and patients from Family 2, suggesting that unknown, possibly epigenetic factors, modify the course of the disease. The first symptoms of the disease appeared at the age of 2.5 (a girl from Family 1), 5, and 3 years (girls from Family 2). All patients had the same, novel homozygous c.1580G>T LMNA mutation, resulting in the replacement of arginine 527 by leucine. Computational predictions of such substitution effects suggested that it might alter protein stability and increase the tendency for protein aggregation, and as a result, might influence its interaction with other proteins. In addition, restriction fragment-length polymorphism analysis performed in 178 unrelated individuals showed that up to 1.12% of inhabitants of Northeast Egypt might be heterozygous carriers of this mutation, suggesting the presence of a founder effect in this area.

Cell autonomous and systemic factors in progeria development

Progeroid laminopathies are accelerated aging syndromes caused by defects in nuclear envelope proteins. Accordingly, mutations in the LMNA gene and functionally related genes have been described to cause HGPS (Hutchinson-Gilford progeria syndrome), MAD (mandibuloacral dysplasia) or RD (restrictive dermopathy). Functional studies with animal and cellular models of these syndromes have facilitated the identification of the molecular alterations and regulatory pathways involved in progeria development. We have recently described a novel regulatory pathway involving miR-29 and p53 tumour suppressor which has provided valuable information on the molecular components orchestrating the response to nuclear damage stress. Furthermore, by using progeroid mice deficient in ZMPSTE24 (zinc metalloprotease STE24 homologue) involved in lamin A maturation, we have demonstrated that, besides these abnormal cellular responses to stress, dysregulation of the somatotropic axis is responsible for some of the alterations associated with progeria. Consistent with these observations, pharmacological restoration of the somatotroph axis in these mice delays the onset of their progeroid features, significantly extending their lifespan and supporting the importance of systemic alterations in progeria progression. Finally, we have very recently identified a novel progeroid syndrome with distinctive features from HGPS and MAD, which we have designated NGPS (Néstor-Guillermo progeria syndrome) (OMIM #614008). This disorder is caused by a mutation in BANF1, a gene encoding a protein with essential functions in the assembly of the nuclear envelope, further illustrating the importance of the nuclear lamina integrity for human health and providing additional support to the study of progeroid syndromes as a valuable source of information on human aging.

Néstor–Guillermo progeria syndrome: A novel premature aging condition with early onset and chronic development caused by BANF1 mutations

Progeria syndromes are rare disorders that involve premature aging. Mutations in BANF1 have been recently reported to cause a new hereditary progeroid syndrome that we now propose to call the Néstor-Guillermo progeria syndrome (NGPS). We describe herein the clinical features of the first two NGPS patients, who phenocopy features of classic progerias (i.e., Hutchinson-Gilford progeria syndrome or mandibuloacral dysplasia), such as aged appearance, growth retardation, decreased subcutaneous fat, thin limbs, and stiff joints. However, these NGPS patients have a distinctive phenotype. In their early adulthood (32 and 24 years of age), they have no signs of cardiovascular impairment, diabetes mellitus, or hypertriglyceridemia. In contrast, they suffer profound skeletal abnormalities that affect their quality of life. The observed differences are of utmost importance to patients and their families and palliation of osseous manifestations is a priority, given their relatively long lifespan. We define NGPS as a chronic progeria because of its slow clinical course and relatively long survival, despite its early onset. Understanding the differences between progeria syndromes might contribute to the development of treatment strategies for common skeletal conditions, as well as aging itself.

Proteomic Profiling of Adipose Tissue from Zmpste24−/− Mice, a Model of Lipodystrophy and Premature Aging, Reveals Major Changes in Mitochondrial Function and Vimentin Processing

Lipodystrophy is a major disease involving severe alterations of adipose tissue distribution and metabolism. Mutations in genes encoding the nuclear envelope protein lamin A or its processing enzyme, the metalloproteinase Zmpste24, cause diverse human progeroid syndromes that are commonly characterized by a selective loss of adipose tissue. Similarly to humans, mice deficient in Zmpste24 accumulate prelamin A and display phenotypic features of accelerated aging, including lipodystrophy. Herein, we report the proteome and phosphoproteome of adipose tissue as well as serum metabolome in lipodystrophy by using Zmpste24(-/-) mice as experimental model. We show that Zmpste24 deficiency enhanced lipolysis, fatty acid biogenesis and β-oxidation as well as decreased fatty acid re-esterification, thus pointing to an increased partitioning of fatty acid toward β-oxidation and away from storage that likely underlies the observed size reduction of Zmpste24-null adipocytes. Besides the mitochondrial proteins related to lipid metabolism, other protein networks related to mitochondrial function, including those involved in tricarboxylic acid cycle and oxidative phosphorylation, were up-regulated in Zmpste24(-/-) mice. These results, together with the observation of an increased mitochondrial response to oxidative stress, support the relationship between defective prelamin A processing and mitochondrial dysfunction and highlight the relevance of oxidative damage in lipoatrophy and aging. We also show that absence of Zmpste24 profoundly alters the processing of the cytoskeletal protein vimentin and identify a novel protein dysregulated in lipodystrophy, High-Mobility Group Box-1 Protein. Finally, we found several lipid derivates with important roles in energy balance, such as Lysophosphatidylcholine or 2-arachidonoylglycerol, to be dysregulated in Zmpste24(-/-) serum. Together, our findings in Zmpste24(-/-) mice may be useful to unveil the mechanisms underlying adipose tissue dysfunction and its overall contribution to body homeostasis in progeria and other lipodystrophy syndromes as well as to develop novel strategies to prevent or ameliorate these diseases.

NCPAP Improves the Quality of Life of Siblings with Mandibuloacral Dysplasia

Mandibuloacral dysplasia (MAD; MIM 248370, 608612) is a rare progeroid syndrome with autosomal reces- sive inheritance. It is characterized by mandibular hypoplasia, acroosteolysis, delayed closure of the cranial sutures, skin atrophy with mottled hyperpigmentation, stiff joints, and growth retardation. We here report Japanese female siblings with a severe MAD phenotype. Because of extreme micrognathia and small mouth and nostril, obstructive sleep apnea syn- drome (OSAS) was observed in both sisters and was especially life-threatening in the younger sister. Nasal continuous positive airway pressure (nCPAP), which seemed to be only one therapeutic choice for these sisters since impaired bone healing made oral surgical approach including maxillomandibular advancement surgery inapplicable to these sisters, suc- cessfully alleviated OSAS in both sisters. Since the initiation of nCPAP, the younger sister has gained weight constantly and her developmental milestones have been steadily achieved. We conclude that possible life threatening sleep- disordered breathing in the patients with progeroid syndromes should be properly managed.

Osteoblasts from a mandibuloacral dysplasia patient induce human blood precursors to differentiate into active osteoclasts

Mandibuloacral dysplasia type A (MADA) is a rare disease caused by mutations in the LMNA gene encoding A type lamins. Patients affected by mandibuloacral dysplasia type A suffer from partial lipodystrophy, skin abnormalities and accelerated aging. Typical of mandibuloacral dysplasia type A is also bone resorption at defined districts including terminal phalanges, mandible and clavicles. Little is known about the biological mechanism underlying osteolysis in mandibuloacral dysplasia type A. In the reported study, we analyzed an osteoblast primary culture derived from the cervical vertebrae of a mandibuloacral dysplasia type A patient bearing the homozygous R527H LMNA mutation. Mandibuloacral dysplasia type A osteoblasts showed nuclear abnormalities typical of laminopathic cells, but they proliferated in culture and underwent differentiation upon stimulation with dexamethasone and beta-glycerophosphate. Differentiated osteoblasts showed proper production of bone mineral matrix until passage 8 in culture, suggesting a good differentiation activity. In order to evaluate whether mandibuloacral dysplasia type A osteoblast-derived factors affected osteoclast differentiation or activity, we used a conditioned medium from mandibuloacral dysplasia type A or control cultures to treat normal human peripheral blood monocytes and investigated whether they were induced to differentiate into osteoclasts. A higher osteoclast differentiation and matrix digestion rate was obtained in the presence of mandibuloacral dysplasia type A osteoblast medium with respect to normal osteoblast medium. Further, TGFbeta 2 and osteoprotegerin expression were enhanced in mandibuloacral dysplasia type A osteoblasts while the RANKL/osteoprotegerin ratio was diminished. Importantly, inhibition of TGFbeta 2 by a neutralizing antibody abolished the effect of mandibuloacral dysplasia type A conditioned medium on osteoclast differentiation. These data argue in favor of an altered bone turnover in mandibuloacral dysplasia type A, caused by upregulation of bone-derived stimulatory cytokines, which activate non-canonical differentiation stimuli. In this context, TGFbeta 2 appears as a major player in the osteolytic process that affects mandibuloacral dysplasia type A patients.

Type B mandibuloacral dysplasia with congenital myopathy due to homozygous ZMPSTE24 missense mutation

Mutation in ZMPSTE24 gene, encoding a major metalloprotease, leads to defective prelamin A processing and causes type B mandibuloacral dysplasia, as well as the lethal neonatal restrictive dermopathy syndrome. Phenotype severity is correlated with the residual enzyme activity of ZMPSTE24 and accumulation of prelamin A. We had previously demonstrated that a complete loss of function in ZMPSTE24 was lethal in the neonatal period, whereas compound heterozygous mutations including one PTC and one missense mutation were associated with type B mandibuloacral dysplasia. In this study, we report a 30-year longitudinal clinical survey of a patient harboring a novel severe and complex phenotype, combining an early-onset progeroid syndrome and a congenital myopathy with fiber-type disproportion. A unique homozygous missense ZMPSTE24 mutation (c.281T>C, p.Leu94Pro) was identified and predicted to produce two possible ZMPSTE24 conformations, leading to a partial loss of function. Western blot analysis revealed a major reduction of ZMPSTE24, together with the presence of unprocessed prelamin A and decreased levels of lamin A, in the patient's primary skin fibroblasts. These cells exhibited significant reductions in lifespan associated with major abnormalities of the nuclear shape and structure. This is the first report of MAD presenting with confirmed myopathic abnormalities associated with ZMPSTE24 defects, extending the clinical spectrum of ZMPSTE24 gene mutations. Moreover, our results suggest that defective prelamin A processing affects muscle regeneration and development, thus providing new insights into the disease mechanism of prelamin A-defective associated syndromes in general.

Elbow deformities in a patient with mandibuloacral dysplasia type A

Elbow deformities in a patient with mandibuloacral dysplasia type A