Delayed closure of fontanelles

The posterior fontanelle (lambdoid fontanelle, occipital fontanelle) is a gap between bones in the human skull (known as fontanelle), triangular in form and situated at the junction of the sagittal suture and lambdoidal suture. It generally closes in 6–8 weeks from birth. [Source: Wikipedia ]

May Be Caused by

Common: Cleidocranial dysostosis; Cranium bifidum with lacunar skull; Hypothyroidism; Infantile hypothyroidism; Intrauterine growth retardation; Osteogenesis imperfecta; Premature birth; Prenatal infection; Severe rickets; Trisomy 21
Uncommon: Aase syndrome; Aminopterin fetopathy; Aplasia cutis congenita; Chondrodysplasia punctata; Coffin-Lowry syndrome; Cutis laxa type 2; Familial idiopathic osteoarthropathy; Fetal hydantoin syndrome; Fetal primidone syndrome; Frontonasal dysplasia; GAPO syndrome; Greig cephalopolysyndactyly syndrome; Hallermann-Streiff syndrome; Hypochondroplasia; Hypophosphatasia; Infantile multisystem inflammatory disease; Kenny-Caffey syndrome; Lenz-Majewski dysplasia; Melnick-Needles osteodysplasty; Microcephalic osteodysplastic dysplasia; Occipital horn syndrome; Oculo-auriculo-vertebral spectrum; Opitz BBBG syndrome; Opsismodysplasia; Otopalatodigital syndrome type 2; Progeria; Pyknodysostosis; Rubinstein-Taybi syndrome; Schinzel-Giedion syndrome; Silver-Russell syndrome; Trisomy 13; Trisomy 18; Winchester syndrome; Yunis-Varon syndrome; Zellweger syndrome