Diffuse, mottled hyperpigmentation and mutations in LMNA gene in a 5-year-old boy, his mother, and his grandmother: Atypical progeroid syndrome

We present a multigenerational family with a phenotypic spectrum of skin dyspigmentation, lipodystrophy, bony anomalies, and progeroid facies. All were found to be heterozygous for a c.11C>G (p.Pro4Arg) (P4R) mutation in the lamin A/C gene consistent with atypical progeroid syndrome. Various phenotypic associations have been reported with specific mutations in atypical progeroid syndrome, but the strength of each phenotype-genotype relationship is unknown. This report adds to the literature of patients with atypical progeroid syndrome and highlights an unusual diagnosis that may present to dermatologists.

Multigenic Disease and Bilineal Inheritance in Dilated Cardiomyopathy Is Illustrated in Nonsegregating LMNA Pedigrees

BACKGROUND

We have previously described 19 pedigrees with apparent lamin (LMNA)-related dilated cardiomyopathy (DCM) manifesting in affected family members across multiple generations. In 6 of 19 families, at least 1 individual with idiopathic DCM did not carry the family's LMNA variant. We hypothesized that additional genetic cause may underlie DCM in these families.

METHODS

Affected family members underwent exome sequencing to identify additional genetic cause of DCM in the 6 families with nonsegregating LMNA variants.

RESULTS

In 5 of 6 pedigrees, we identified at least 1 additional rare variant in a known DCM gene that could plausibly contribute to disease in the LMNA variant-negative individuals. Bilineal inheritance was clear or presumed to be present in 3 of 5 families and was possible in the remaining 2. At least 1 individual with a LMNA variant also carried a variant in an additional identified DCM gene in each family. Using a multivariate linear mixed model for quantitative traits, we demonstrated that the presence of these additional variants was associated with a more severe phenotype after adjusting for sex, age, and the presence/absence of the family's nonsegregating LMNA variant.

CONCLUSIONS

Our data support DCM as a genetically heterogeneous disease with, at times, multigene causation. Although the frequency of DCM resulting from multigenic cause is uncertain, our data suggest it may be higher than previously anticipated.