ATR-X is an acronym for alpha-thalassemia, mental
retardation, X-linked syndrome. It is characterized by genital abnormalities,
microcephaly, midface hypoplasia, severe mental retardation, neuromotor
dysfunction, seizures, and hypotonia. Occasionally, the patient presents
with a ventricular septal defect and gastrointestinal reflux.
X-Linked Mental Retardation Hypotonic Face Syndrome; XLMR
Hypotonic Face Syndrome.
Caused by mutations of the ATR-X gene. It is
inherited as an X-linked dominant transmission, and only males are affected.
α-Thalassemia/mental retardation syndrome also has been suggested to
be a contiguous gene syndrome resulting from deletion in 16p.
There are four subtypes of α-thalassemia.
In the presence of a defect on the one α-globin gene, the patient
presents with no symptoms of anemia and requires no treatment. The patient
is known as a silent carrier. If two α-globin genes are missing or damaged, the
condition is known as α-thalassemia minor or α-thalassemia
trait. In the case of three missing α-globin genes, the person has
mild-to-moderately severe anemia, and this condition is termed hemoglobin H disease because it
causes production of a heavy hemoglobin that is less stable than
normal hemoglobin. The mild forms may not require any treatment. The more
severe forms usually do not require treatment with blood transfusions except
during periods of stress on the body (such as infection). If all four
α-globin genes are missing, the child will die before birth. This
hemoglobin sometimes is called hemoglobin Bart.
X-linked inherited recessive
disorder resulting from a defect in the gene encoding X-linked helicase-2.
The helicases are involved in numerous intracellular functions, including
DNA recombination and regulation of transcription. It also has been
suggested to result from a deletion in the 16p gene.
Patients affected with this disorder present with
significant postnatal growth deficiency and mental retardation with absent
speech capability. The clinical characteristics describing this entity are
numerous and include microcephaly, midface hypoplasia, low-set ears that are
rotated posteriorly, low nasal bridge, carp-shaped mouth, full lips, and
large protruding tongue. The cardiovascular system is most often affected
with a perimembranous ventricular septal defect. The shape of the chest is
abnormal because ribs are frequently missing. Most patients have hernias and
gastroesophageal reflux. The genitourinary system shows hypospadias, small
penis, shawl scrotum, cryptorchidism. Renal function demonstrates
hydronephrosis and renal agenesis. Neurologically, besides severe mental
retardation, spasticity and seizures activity resulting from cerebral
atrophy are the most frequent features. Defects of the musculoskeletal
system show kyphoscoliosis resulting from hemivertebrae, coxa valga of the
pelvis, tapering fingers, fifth finger clinodactyly, and a talipes
equinovarus prominent in the feet. The hematology system shows mild
hypochromic microcytic anemia and a mild form of hemoglobin H disease. The
disease presents with all hematologic characteristics of an α-thalassemia
Complete hematologic evaluation must
be obtained before surgery. The hematocrit should be checked because of the
high incidence of anemia. The cardiovascular system should be assessed and
an echocardiogram obtained. ...