Coexistent mosaic monosomy 21 and fragile X syndrome in a mentally retarded male patient.

[monosomy 21]

Fragile X syndrome (FXS ) is a well-recognized mental retardation syndrome with characteristic facial features and behavioural phenotype . Monosomy 21 is a rare cytogenetic aberration for which clinical features were incompletely defined since full monosomy 21 is incompatible with life . A 5 -year -old male patient with FXS and low -grade mosaicism for full monosomy 21 (46 ,XY [96 %]/45 ,XY ,-21 [4 %]) is presented . He had lack of speech and severely impaired social skills , hyperactivity , stereotypical hand movements , a special interest towards moving colourful items and a short attention span for other objects around . He had macrocephaly , a rather long face , prominent occiput and prominent midface , retrognathia , down-slanting palpebral fissures , hypertelorism and cup-shaped , posteriorly rotated and low-set ears . Full monosomy in the aberrant cell line was proven by whole chromosome painting . FXS was previously reported to accompany sex chromosome aneuploidies ; however , to the best of our knowledge , the present patient is the first FXS patient with an aberration involving autosomes . He contributes to the current knowledge on monosomy 21 phenotype , having dysmorphic facial findings despite the concurrent phenotypic expression of the FXS . As a last conclusion , cytogenetic analysis must be done to all mentally retarded patients with minor dysmorphic features .

Diseases
Validation

Diseases presenting "mental retardation" symptom

achondroplasia

alexander disease

alpha-thalassemia

aniridia

aromatase deficiency

canavan disease

classical phenylketonuria

coats disease

cohen syndrome

cowden syndrome

cystinuria

dentin dysplasia

familial hypocalciuric hypercalcemia

homocystinuria without methylmalonic aciduria

hydrocephalus with stenosis of the aqueduct of sylvius

kabuki syndrome

kallmann syndrome

lamellar ichthyosis

lymphangioleiomyomatosis

monosomy 21

phenylketonuria

primary hyperoxaluria type 1

proteus syndrome

pyruvate dehydrogenase deficiency

sneddon syndrome

triple a syndrome

wolf-hirschhorn syndrome

zellweger syndrome

This symptom has already been validated