Autosomal recessive inherited disorder characterized
by prenatal and postnatal growth retardation, photosensitivity,
telangiectasias, skin pigment anomalies, and increased risk of malignancies
most likely as a consequence of chromosomal instability.
Perioral and facial telangiectasias in a boy with Bloom syndrome.
Congenital Telangiectatic Erythema; Bloom-Torre-Machacek
1:160,000 live births. More common in Ashkenazi Jews
from Eastern Europe.
Autosomal recessive. Gene map locus 15q26.1.
The protein BLM encoded by the normal gene acts in the
maintenance of genomic stability. A mutation in this gene results in Bloom Syndrome.
Spontaneous chromosome breakage with
exchanges between homologous chromosome segments lead to increased sister
chromatid exchanges and are assumed to be responsible for the phenotype and
the predisposition to neoplasias.
Clinical signs plus chromosomal and DNA analysis.
Amniocentesis for amniotic fluid cell culture with assessment of the number
of sister chromatid exchanges allows prenatal diagnosis.
Prenatal and postnatal growth retardation are
hallmarks of this syndrome and usually the first reason to seek medical
attention. Clinical signs include dolichocephaly and malar hypoplasia
resulting in a “bird-like” face, photosensitivity with telangiectasias in
the face and other sun-exposed areas (butterfly-like midface distribution;
plaques or macules in other locations), and café-au-lait spots.
Pulmonary fibrosis, bronchiectasis, cardiomyopathy, primary hypogonadism
and mental retardation are variable findings. Adult-onset diabetes mellitus
may occur in the second or third decade of life. Immunocompromise is caused by
decreased levels of IgM and IgA and can result in life-threatening
gastrointestinal and respiratory infections. Predisposition to neoplasias is
another important feature, with an up to 300-fold increased risk of
malignancies compared to the normal population (especially lymphomas,
leukemias, squamous cell carcinomas, and gastrointestinal adenocarcinomas).
Approximately 20% of patients will experience one (or more) neoplasia(s),
which may present as early as 4 years of age but is most common in the
mid-twenties for leukemias and lymphomas and in the mid-thirties for solid tumors.
Patients are at risk for developing diabetes mellitus in the second or third
decade of life.
Obtain a full history. Check blood
glucose profile and levels in case of diabetes mellitus. Rule out
mediastinal mass in the presence of lymphoma or leukemia. Check respiratory and
cardiac function (clinical, chest radiography, echocardiography, arterial blood
gas analysis, pulmonary function tests).
Strict asepsis for these patients is
mandatory and reverse isolation must be considered. Enforce aggressive
pulmonary toilet in the presence of bronchiectases. Perioperative cardiac
and respiratory monitoring should be considered.
Avoid myocardial depressant drugs in
the presence of cardiomyopathy. Consider prophylactic antibiotics as in
Porphyrias: a group of disorders characterized by enzymatic defects in the
heme biosynthesis. Depending on the primary location of the defect, the porphyrias are
classified as erythropoietic and hepatic forms.