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In This Issue of Archives of Internal Medicine
Arch Intern Med. 2001;161:2405.
Association of Mutations in the Hemochromatosis Gene With Shorter Life
Expectancy
Bathum and colleages investigated whether the frequency of carriers
for hereditary hemochromatosis changes as a function of age. Genotyping for
the C282Y mutation in the HFE gene (the mutation
most often associated with hereditary hemochromatosis) was performed in 1784
subjects aged 45 to 100 years, and a trend toward fewer heterozygotes with
age was found. The trend was statistically significant for the whole population
and for women, but not for men. This age-related reduction suggests that carrier
status is associated with shorter life expectancy.
(SEE ARTICLE)
Genetic Analysis as a Valuable Key to Diagnosis and Treatment of Periodic
Fever
In this case report, Simon et al demonstrate the importance of adequately
examining family history in a patient with unexplained periodic fever episodes.
In the 2 cases described, subsequent genetic analysis of the gene for the
tumor necrosis factor (TNF) receptor led to a diagnosis of TNF receptorassociated
periodic syndrome (TRAPS), an autosomal dominantly inherited disorder characterized
by episodes of fever, arthralgia, and skin lesions. Elucidation of the molecular
background has facilitated the treatment of TRAPS because blocking of TNF
signaling seems to alleviate the symptoms.
(SEE ARTICLE)
mtDNA Disease in the Primary Care Setting
Mitochondrial DNA (mtDNA) mutations are surprisingly common, with a
prevalence of up to 10% in patients with diabetes mellitus, hearing loss,
or renal failure. A 36-year-old man with a history of psychosis, seizures,
sensorineural hearing loss, and a family history of diabetes mellitus and
heart disease had undergone evaluation by primary care physicians for 15 years
without a unifying diagnosis. Physiologic, biochemical, and genetic testing
established the diagnosis of mitochondrial encephalopathy, lactic acidosis,
and stroke-like syndrome. Diagnosing mtDNA disorders requires a careful integration
of clinical signs and symptoms with pedigree analysis and multidisciplinary
testing. Diagnosis is important to provide genetic counseling, avoid unnecessary
evaluation, and facilitate therapy for symptomatic relief.
(SEE ARTICLE)
Genotype and Phenotype Analysis of 171 Patients Referred for Molecular
Study of the Fibrillin-1 Gene FBN1 Because of Suspected
Marfan Syndrome
In this study, the clinical and molecular data were reviewed for 171
consecutive patients referred for FBN1 analysis because
of a diagnosis of Marfan syndrome (MFS) or signs suggestive of MFS. A diagnosis
of MFS based on the Ghent criteria was highly correlated with an FBN1 mutation (66%). Fifty percent of children with "emerging" MFS
had mutations, whereas only 5% of patients with Marfan-related conditions
had mutations. These data show first that a comprehensive clinical evaluation
is mandatory before establishing a definitive diagnosis and second, that FBN1 mutation analysis may be helpful, particularly in
families displaying phenotypic variability or to identify children at risk
for MFS who need careful clinical follow-up.
(SEE ARTICLE)
Hereditary Angioedema: A Broad Review for Clinicians
Hereditary angioedema (HAE) is an autosomal dominant disease that afflicts
l in 10 000 to 1 in 150 000 persons. It is an uncommon condition
that may present with rather common symptoms and may be misdiagnosed in certain
circumstances. Hereditary angioedema manifests as recurrent attacks of intense,
massive, localized edema without concomitant pruritus. Skin, as well as visceral
organs, may be involved by the typically massive local edema. Involvement
of the upper airways may result in severe life-threatening symptoms, including
the risk of asphyxiation, unless appropriate interventions are taken. Historically,
2 types of HAE have been described; however, a variant, possibly X-linked,
inherited angioedema has recently been described and tentatively named "type
3" HAE. Clinicians should keep this group of disorders in their differential
diagnosis of unexplained episodic cutaneous angioedema or unexplained abdominal
pain.
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HMWK indicates high-molecular-weight kininogen; MAC, membrane attack
complex.
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(SEE ARTICLE)
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