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Chromosome 10

10q deletion occurs de novo and shows various malformations, high wide forehead with normocephaly, wide and bulbous tip of the nose, microretrognathia and severe mental retardation. This monosomy is rather rare and is reportedly associated with total colonic aganglionosis with small bowel involvement (TCSA), a variant of Hirschsprung disease.

The clinical phenotype of 10p duplication, which is due to malsegregation of a familial translocation, includes severe postnatal growth retardation, profound mental retardation, several major and minor anomalies, dolichocephaly, harelip producing the appearance of a turtles beak, cleft lip/palate in the absence of harelip, large low set ears, osteoarticular anomalies with hyperflexion of upper limbs and abduction-flexion of lower limbs, etc. Lethality seems considerable.

Most cases of trisomy 10qter result from a parental translocation or inversion. More severe clinical manifestations are reported for trisomy 10q24, owing to heart and renal malformations and profound mental retardation. Trisomy 10q25 lacks major malformations, the mental retardation is 1000 moderate and the prognosis is favourable. The clinical features include high protruding forehead, round, broad and flat face, fine and arched eyebrows, downward slanting palpebral fissures, blepharophimosis, hypertelorism, hypoplastic and pinched nasal bridge, a small and often beaked nose, cleft palate, ligamentary hyperlaxity, and hypotonia. Inner organ malformations are rare but mental deficiency is severe. 10q monosomy is quite rare and the main features are severe mental retardation, microcephaly, low birth weight, prominent nose bridge, long face, and anomalies of external genitalia. The phenotype of ring chromosome 10 is not very characteristic and includes cardiac and renal anomalies, small stature and moderate mental retardation.

Prenatal diagnosis of trisomy 10 is reported. Dysmorphic features include foetal nuchal edema, cleft lip/palate, small lower jaw, rocker-bottom foot, polydactyly, hitch-hiker thumb, syndactyly and inner organ malformations.

genes on chromosome 10 include those encoding glutamate oxaloacetate transaminase, orithine amino transferase and hexokinase 1. Chromosome 10 shows 2 fragile sites in the long arm, 10q23 and 10q25, which probably accounts for its increased involvement in chromosomal anomalies.