Two unrelated children with partial trisomy 1q and monosomy 6p, presenting with the phenotype of the Larsen syndrome

Abstract

Two unrelated children presented with similar clinical features (facial dysmorphism and multiple joint dislocations) suggesting the diagnosis of Larsen syndrome. Both carried an inherited unbalanced translocation resulting in partial trisomy 1q and partial monosomy 6p. Analysis of skin collagen from one of the probands disclosed a decreased alpha 1/alpha 2 chain ratio of collagen type I, increased thermal stability and increased hydroxylation of proline and lysine. The present findings suggest that, as a result of the chromosome rearrangements, both patients have a mutation on a gene involved in collagen production, located either on chromosome 1q or, more probably, on 6p. It is furthermore suggested that other cases of Larsen syndrome are the result of a similar mutation.

The 6p25 deletion syndrome: An update on a rare neurocristopathy

“…The presence of ASD is reported in 83% of 6p25 deletion syndrome patients (present in 49 out of 59 reported cases, see Table 1). 10,11,[13][14][15][27][28][29][30][31][32][33][34][35] Iris coloboma has been reported in few patients with isolated 6p25 deletion. 14,31 Glaucoma is a common finding, present in about half of patients.…”

“…14,[27][28][29][30][31] Retinal anomalies, in particular pigmentary changes, have been reported in about 24%. 10,14,15,27,29,30,32,35,36 Craniofacial dysmorphism Almost all 6p25 deletion patients have some form of craniofacial dysmorphism. The typical facial appearance consists of hypertelorism (present in 93%), downslanting palpebral fissures (69%), and midface hypoplasia with flat, broad nasal bridge (77%).…”

“…The typical facial appearance consists of hypertelorism (present in 93%), downslanting palpebral fissures (69%), and midface hypoplasia with flat, broad nasal bridge (77%). 14,15,[27][28][29][30][31][32][34][35][36] In addition, a prominent forehead (present in 51%), micrognathia (21%) and tented mouth (48%) with various dental anomalies (44%) can be present. 11,[13][14][15][27][28][29][30][31][32][34][35][36] External ears are frequently low set (58%) and are often malformed (39%).…”

“…14,15,[27][28][29][30][31][32][34][35][36] In addition, a prominent forehead (present in 51%), micrognathia (21%) and tented mouth (48%) with various dental anomalies (44%) can be present. 11,[13][14][15][27][28][29][30][31][32][34][35][36] External ears are frequently low set (58%) and are often malformed (39%). 14,15,[27][28][29][30][31][32][34][35][36] Microcephaly has been described in several cases.…”

“…11,[13][14][15][27][28][29][30][31][32][34][35][36] External ears are frequently low set (58%) and are often malformed (39%). 14,15,[27][28][29][30][31][32][34][35][36] Microcephaly has been described in several cases. 29,36 Additionally the palate can be highly arched (29%) and lip, palate, or uvula is cleft in 20% of patients.…”