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J Clin Endocrinol Metab. 2007 Nov;92(11):4467-71. Epub 2007 Sep 11.

Compound heterozygosity for mutations in LMNA in a patient with a myopathic and lipodystrophic mandibuloacral dysplasia type A phenotype.

Author information

1
Department of Biopathology and Diagnostic Imaging, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.

Abstract

CONTEXT:

Mandibuloacral dysplasia type A (MADA; OMIM 248370) is a rare progeroid syndrome characterized by dysmorphic craniofacial and skeletal features, lipodystrophy, and metabolic complications. Most Italian patients carry the same homozygous missense mutation (p.R527H) in the C-terminal tail domain of the LMNA gene, which encodes lamin A/C, an intermediate filament component of the nuclear envelope.

OBJECTIVE:

The objective of the study was to identify novel LMNA mutations in individuals with clinical characteristics (bird-like facies, mandibular and clavicular hypoplasia, acroosteolysis, lipodystrophy, alopecia) observed in other well-known patients.

DESIGN:

The LMNA gene was sequenced. Functional properties of the mutant alleles were investigated.

PATIENT:

We report a 27-yr-old Italian woman showing a MADA-like phenotype. Features include a hypoplastic mandible, acroosteolysis, pointed nose, partial loss of sc fat, and a progeric appearance. Due to the absence of clavicular dysplasia and normal metabolic profiles, generally associated with muscle hyposthenia and generalized hypotonia, this phenotype can be considered an atypical laminopathy.

RESULTS:

We identified a patient compound heterozygote for the p.R527H and p.V440M alleles. The patient's cells showed nuclear shape abnormalities, accumulation of pre-lamin A, and irregular lamina thickness. Lamins A and C showed normal expression and localization. The electron microscopy detected heterochromatin defects with a pattern similar to those observed in other laminopathies. However, chromatin analysis showed a normal distribution pattern of the major heterochromatin proteins: heterochromatin protein-1beta and histone H3 methylated at lysine 9.

CONCLUSIONS:

The clinical and cellular features of this patient show overlapping laminopathy phenotypes that could be due to the combination of p.R527H and p.V440M alleles.

PMID:
17848409
DOI:
10.1210/jc.2007-0116
[Indexed for MEDLINE]

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