ABSTRACT
A rare form of osteogenesis imperfecta (OI) caused by Wingless-type MMTV integration site family 1 (WNT1) mutations combines central nervous system (CNS) anomalies with the characteristic increased susceptibility to fractures. We report an additional case where arachnoid cysts extend the phenotype, and that also confirms the association of intellectual disabilities with asymmetric cerebellar hypoplasia here. Interestingly, if the cerebellum is normal in this disorder, intelligence is as well, analogous to an association with similar delays in a subset of patients with sporadic unilateral cerebellar hypoplasia. Those cases typically appear to represent vascular disruptions, and we suggest that most brain anomalies in WNT1-associated OI have vascular origins related to a role for WNT1 in CNS angiogenesis. This unusual combination of benign cerebellar findings with effects on higher functions in these two situations raises the possibility that WNT1 is involved in the pathogenesis of the associated sporadic cases as well. Finally, our patient reacted poorly to pamidronate, which appears ineffective with this form of OI, so that a lack of improvement is an indication for molecular testing that includes WNT1.
Subject(s)
Central Nervous System/physiopathology , Intellectual Disability/genetics , Osteogenesis Imperfecta/genetics , Wnt1 Protein/genetics , Arachnoid Cysts/diagnostic imaging , Arachnoid Cysts/physiopathology , Central Nervous System/abnormalities , Central Nervous System/diagnostic imaging , Cerebellum/abnormalities , Cerebellum/diagnostic imaging , Cerebellum/physiopathology , Developmental Disabilities/diagnostic imaging , Developmental Disabilities/genetics , Developmental Disabilities/physiopathology , Frontal Lobe/diagnostic imaging , Frontal Lobe/physiopathology , Humans , Intellectual Disability/diagnostic imaging , Intellectual Disability/drug therapy , Intellectual Disability/physiopathology , Mutation , Nervous System Malformations/diagnostic imaging , Nervous System Malformations/genetics , Nervous System Malformations/physiopathology , Osteogenesis Imperfecta/diagnostic imaging , Osteogenesis Imperfecta/drug therapy , Osteogenesis Imperfecta/physiopathology , Pamidronate/administration & dosage , Pamidronate/adverse effectsABSTRACT
OBJECTIVE: To evaluate thyroid function in children with Down's syndrome, and to ascertain the presence of a relationship between overt thyroid diseases and congenital anomalies. MATERIAL AND METHOD: One hundred and forty Down's syndrome patients, aged from 3 days to 13 years 9 months, were evaluated for karyotype, thyroid functions and the coexistence of congenital anomalies. RESULTS: Trisomy 21 was found in the majority of cases (95.7%). Fifty-six patients (40%) had abnormal thyroid functions: 53 (37.9%) hypothyroidism and 3 (2.1%) hyperthyroidism. Ten patients (7.1%) were diagnosed with overt thyroid disease: congenital hypothyroidism 3.6%, acquired hypothyroidism associated autoimmune thyroiditis 1.4% and hyperthyroidism 2.1%. None of the patients with congenital hypothyroidism had athyreosis or ectopic thyroid gland. Sub-clinical hypothyroidism accounted for 32.9% of all cases; 10.7% showed a spontaneous decrease to normal TSH levels and 13.6% had persistently elevated TSH levels with the median follow-up time of 6 and 12 months, respectively. Congenital heart disease, gastrointestinal anomalies and hematological disease were found in 73.6, 10 and 3.6 percent of patients, respectively. There was no statistical correlation between the coexistence of cardiovascular or gastrointestinal disease in Down's syndrome patients with overt thyroid diseases or sub-clinical hypothyroidism to those having normal thyroid functions. CONCLUSION: Sub-clinical hypothyroidism was the most common thyroid abnormality in children with Down's syndrome. A longitudinal and timely-scheduled evaluation of thyroid function is needed to establish the natural course of this abnormality and the proper management guideline.
