Document Type : Case Report
Authors
1 Department of Medical Genetic, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran;Iranian Academic Center for Education, Culture and Research (ACECR), Mashhad, Iran;Medical Genetic Research Center (MGRC), S
2 4Department of Neurology, Mashhad University of Medical Sciences, Ghaem hospital, Mashhad, Iran
Abstract
Keywords
A chromosome anomaly can be (a) Numerical: there
is one (or more) chromosome(s) in excess (trisomy) or
missing (monosomy) resulting in the karyotype being
always unbalanced and (b) Structural: the change is
balanced, if there is no loss or gain of genetic material
but unbalanced, if there is deletion and/or duplication
of chromosome segment(s). In an unbalanced chromosome rearrangement, the chromosomal complement
contains an incorrect amount of chromosome material
and the clinical effects are usually serious. Duplication
is one of the structural changes that results in an unbalanced rearrangement. There are two types of duplication: 1. Direct: segment of chromosome is repeated,
once or several times, the duplicated segment keeping
the same orientation with respect to the centromere
("tandem duplication") and 2. Inverted: the duplicated
segment takes the opposite orientation (
Chromosomes in the human genome is the
chromosome 14, the short arm of this chromosome is characterized by heterochromatin which
contain ribosomal RNA genes. The long arm of
this chromosome is euchromatin that most of the
geneslocatedon , is the protein-codinggenes (
The chromosome 14 is one of the human chromosomes known to have an imprinting affect. In
the human chromosome, 14-uniparental disomy
(UPD) describes the inheritance of both the homologs of a pair of chromosomes from an individual parent. Though genomic imprinting is correct
in UPD, problems arise due to the normal chromosome segregation, therefore causing false imprinting. The phenotypes have been described for
maternal UPD 14 respectively (
Paternal UPD 14 is associated with developmental delay. Both maternal UPD 14 and paternal UPD 14 rarely appear in individuals .
Here we describe the clinical features associated
with a dup (
In a cousin marriage between a 29 year old
female and a 35 year old male, following a 15
hours prolonged labor, a child was born by caesarean section. The infant’s weight, height and
head circumference at birth were 2200 g, 46 cm
and 31cm respectively. The result in biochemistry
was creatine 0.4 mg/l, in hematology HCT 25%,
platelet 530000, PT 16.5 sec. PTT 36 sec and INR
1.5. Overtime the mother noticed delay in the
growth and development of the child and opted
for a different workup. In the new laboratory assessments , the following findings were observed :
Zinc: 59 mcg/dl (N: 63.8-110), Sweat test: (weight
529 mg, Cl-
Following abnormal ABG and mild cyanosis in
the patient, echocardiography was carried out and
the results were PDA, ASD20size 7-8mm, L->R
shunt, good ejection fraction and no pulmonary
hypertension. The patient underwent surgery via
Video-Assissted Thoracoscopy (VATS) and Ductus which was closed using double liga clips. Since
then her weight loss has continued. She received
hormone therapy which was rendered ineffective
and finally a genetic consultation was carried out.
The patient was admitted to the Imam Khomeini
Hospital in Tehran on 03.09.2010 at the age of 34
months. At present, the girl’s weight and height are
at 7100 g and 54 cm respectively. She has gained
the ability to sit and as of lately can manage a few
one-syllable words. She suffers from skin allergy,
insomnia and recurrent gastroenteritis and is undergoing physiotherapy and occupational therapy.
The patient was diagnosed to be mentally impaired
with an unusual facial feature, including a high
forehead, epicanthic folds, large and low set ears,
a small jaw and chin and also a large tongue. In
her lower extremities, overlapping toes was noted.
A neurological examination revealed evidence of
generalized weakness accompanied with reduced
muscle tone, diminished deep tendon reflexes and some diatonic features in the distal parts of the
extremities. Due to muscle weakness in the lower
limbs, the patient was unable to walk unassisted
and also had difficulty in sitting (
Examination revealed evidence of generalized weakness with reduced muscle tone and diminishment. Patient was unable to walk unassisted and also had difficulty sitting.
Conventional cytogenetic analysis of cultured lymphocytes was performed. Blood samples were obtained through venipuncture and collected into heparinized syringes. For each 2 subject, three lymphocyte cultures were usually set up according to conventional techniques. Cultures were made in Ham’s F10 (Biochrom) medium supplemented with LymphoGrow (100ml; Complete medium 12% newborn calf serum, 7.8 μg/ml Phytohaemagglutinin (PHA, CytoGen, Germany), LymphoGrow II (100ml; Complete medium 14% newborn calf serum, 8.8 μg/ml phytohemagglutinin) (CytoGen, Germany). The cells were grown at 37˚C for 48 to 72 hours. Cultures were treated with colchicine (10 μg/ml) (Life Technologies/Invitrogen) during the last 3hrs of incubation. Cultures were harvested using protocol, including hypotonic treatment of 0.56% KCl (0,065 M) (Merck/ VWR) for 20 minutes at 37˚C and three periods of fixation in methanol: glacial acetic acid (3:1). Flame-dried slides were prepared and stained by Giemsa technique. Cytogenetic analysis revealed a 46, XX, dup (14) karyotype (Fig 2). The rearrangement was present in all the 25 analyzed cells. Although the breakpoint was difficult to assign, the G-banding displayed duplication of chromosome 14 at region 2 and band 4. The resolution of the banding was approximately 350 bands. Karyotype analysis of the parents signifies that a de novo rearrangement has occured in this particular patient.
Banding of chromosome 14 [dup (
It seems that the chromosomal aberration provides a good explanation for the clinical features
of our patient. Cytogenetic analysis revealed a
46, XX, dup (
Examples of absent parent-specific gene expression include brain specific expression of
UBE3A in Angelman syndrome (
The present study reports a chromosomal duplication syndrome. Our results suggest that genetic counselling and a follow up karyotyping should be performed when an increased nuchal translucency is observed.