A novel homozygous Ala529Val LMNA mutation in Turkish patients with mandibuloacral dysplasia.
BACKGROUND
Mandibuloacral dysplasia (MAD) is a phenotypically heterogeneous, rare autosomal recessive disorder characterized by mandibular and clavicular hypoplasia, acroosteolysis, delayed closure of cranial sutures, joint contractures, lipodystrophy, and mottled cutaneous pigmentation. MAD patients with type A lipodystrophy with loss of sc fat from the extremities and normal or slight excess in the neck and truncal regions have been previously reported to carry a homozygous Arg527His mutation in LMNA (Lamin A/C) gene. Among those with type B pattern of lipodystrophy with generalized loss of sc fat, we recently reported a patient carrying compound heterozygous mutations in an endoprotease, zinc metalloproteinase (ZMPSTE24), gene that is involved in posttranslational processing of prelamin A to mature lamin A.


OBJECTIVE
Our objective was to carry out mutational analysis of LMNA in additional patients with MAD and type A lipodystrophy.


METHODS
We studied descriptive case reports at a referral center.


METHODS
Subjects were a male and a female patient with MAD who belonged to two pedigrees from Turkey.


METHODS
We assessed genotype-phenotype relationships.


RESULTS
We now report that both these patients have a novel homozygous missense mutation (c.1586C-->T; c refers to cDNA reference sequence) in LMNA that replaces a well-conserved residue alanine at position 529 to valine. Intragenic single-nucleotide polymorphisms revealed a common haplotype spanning 2.5 kb around the mutated nucleotide in the parents of both the affected subjects, suggesting ancestral origin of the mutation. The female patient had no breast development despite normal menstruation, a phenotype different from that seen in women with MAD and Arg527His LMNA mutation.


CONCLUSIONS
We conclude that two homozygous missense LMNA mutations involving the arginine 527 and alanine 529 residues cause MAD with subtle variations in phenotype.
Division of Nutrition and Metabolic Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9052, USA. Abhimanyu.garg@utsouthwestern.edu
Abhimanyu
A
Garg
Ozgur
O
Cogulu
Ferda
F
Ozkinay
Huseyin
H
Onay
Anil K
AK
Agarwal
D000015:Abnormalities, Multiple / Q000235:genetics; D000293:Adolescent; D000409:Alanine; D001842:Bone and Bones / Q000002:abnormalities* / Q000000981:diagnostic imaging; D001940:Breast / Q000002:abnormalities; D019465:Craniofacial Abnormalities / Q000235:genetics* / Q000473:pathology; D004252:DNA Mutational Analysis; D005260:Female; D006130:Growth Disorders / Q000235:genetics*; D006239:Haplotypes; D006720:Homozygote; D006801:Humans; D034904:Lamin Type A; D034882:Lamins / Q000235:genetics*; D008297:Male; D009154:Mutation; D020125:Mutation, Missense; D010375:Pedigree; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011859:Radiography; D012871:Skin Diseases / Q000235:genetics*; D014421:Turkey; D014633:Valine
C494847:LMNA protein, human; D034904:Lamin Type A; D034882:Lamins; D014633:Valine; D000409:Alanine