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Dissection of partial 21q monosomy in different phenotypes: clinical and molecular characterization of five cases and review of the literature.

ABSTRACT: BACKGROUND:Partial deletion of chromosome 21q is a very rare chromosomal abnormality associated with highly variable phenotypes, such as facial dysmorphic features, heart defects, seizures, psychomotor delay, and severe to mild intellectual disability, depending on the location and size of deletions. So far, three broad deletion regions of 21q have been correlated with the clinical phenotype. RESULTS:We described the clinical and genetic features of three family members (father and two siblings) and other two unrelated patients with very wide range in age of diagnosis. All of them showed intellectual disability with very variable symptoms, from mild to severe, and carried 21q interstitial deletions with different sizes and position, as detected by conventional karyotype and array-CGH. CONCLUSIONS:Our study provided additional cases of partial 21q deletions, allowing to better delineate the genotype-phenotype correlations. In contrast to previous observations, we showed that deletions of the 21q proximal region are not necessarily associated with severe phenotypes and, therefore, that mild phenotypes are not exclusively related to distal deletions. To the best of our knowledge, this is the first report showing 21q deletions in adult patients associated with mild phenotypes, mainly consisting of neurobehavioral abnormalities, such as obsessive-compulsive disorders, poor social interactions and vulnerability to psychosis.

SUBMITTER: Errichiello E

PROVIDER: S-EPMC5020505 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Dissection of partial 21q monosomy in different phenotypes: clinical and molecular characterization of five cases and review of the literature.

Errichiello Edoardo E Novara Francesca F Cremante Anna A Verri Annapia A Galli Jessica J Fazzi Elisa E Bellotti Daniela D Losa Laura L Cisternino Mariangela M Zuffardi Orsetta O

Molecular cytogenetics 20160224 1

<h4>Background</h4>Partial deletion of chromosome 21q is a very rare chromosomal abnormality associated with highly variable phenotypes, such as facial dysmorphic features, heart defects, seizures, psychomotor delay, and severe to mild intellectual disability, depending on the location and size of deletions. So far, three broad deletion regions of 21q have been correlated with the clinical phenotype.<h4>Results</h4>We described the clinical and genetic features of three family members (father an ...[more]

PMID: 27625702

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Project description:BACKGROUND:Cutis tricolor is a skin abnormality consisting in a combination of congenital hyper- and hypopigmented skin lesions (in the form of paired macules, patches or streaks) in close proximity to each other in a background of normal skin. It is currently regarded as a twin-spotting (mosaic) phenomenon and today is clear that not all cases of cutis tricolor represent one single entity. This phenomenon has been reported so far either: (I) as an purely cutaneous trait; (II) as a part of a complex malformation phenotype (Ruggieri-Happle syndrome, RHS) including distinct facial features, eye (cataract), skeletal (skull and vertebral defects, and long bones dysplasia), nervous system (corpus callosum, cerebellar and white matter anomalies, cavum vergae and holoprosencephaly) and systemic abnormalities; (III) as a distinct type with multiple, disseminated smaller skin macules (cutis tricolor parvimaculata); and (IV) in association with other skin disturbances [e.g., cutis marmorata telangectasica congenita (phacomatosis achromico-melano-marmorata)] or in the context of other skin (e.g., ataxia-telangiectasia and phacomatosis pigmentovascularis, PPV) or complex malformation phenotypes (e.g., microcephaly and dwarfism). METHODS:(I) Review of the existing literature; and (II) information on our personal experience (clinical, laboratory and imaging data) on new cases with cutis tricolor seen and followed-up at our institutions during years 2010-2016. RESULTS:The existing literature revealed 19 previous studies (35 cases) with pure cutaneous or syndromic cutis tricolor phenomena. Our personal experience included 5 unpublished patients (3 boys; 2 girls; currently aged 2 to 14 years) seen and followed-up at our Institutions in Italy who had: (I) skin manifestations of the cutis tricolor type (N=5); (II) skeletal abnormalities including small skull (n=2), obtuse angle of mandible (n=3), mild to moderate scoliosis (n=3), vertebral defects (n=3), and long bones bowing (n=3); mild psychomotor delay (n=3); epilepsy (n=2); anomalies of the corpus callosum (n=3); and cavum vergae (n =2). CONCLUSIONS:This study further confirms and expands the overall phenotype of cutis tricolor. By literature review and personal experience we conclude that the skin abnormalities of the cutis tricolor type are stable over time; the skeletal defects are mild to moderate and do not progress or cause relevant orthopaedic complications; the neurological/behavioural phenotype does not progress and the paroxysmal events (when present) tend to decrease over time; there is a typical facial phenotype in some patients (long, elongated face, thick and brushy eyebrows, hypertelorism, deep nasal bridge with large bulbous nose and anteverted nostrils), which characterizes a somewhat distinct syndromic phenotype; some patients may develop early onset cataracts. The allelic dydymotic hypothesis of post-zygotic mutations likely involving the same gene loci could well explain the overall skin, bone, lens and nervous system phenomena of migration of different streaks of clones in the different tissues.

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Dissection of partial 21q monosomy in different phenotypes: clinical and molecular characterization of five cases and review of the literature.

Publications

Dissection of partial 21q monosomy in different phenotypes: clinical and molecular characterization of five cases and review of the literature.

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