Clinical features
The intellectual disability with persistence of fetal hemoglobin syndrome (also known as Dias-Logan syndrome) is a disorder characterized by developmental delay/intellectual disability of variable degree, neonatal hypotonia, microcephaly, distinctive but variable facial characteristics, behavioural problems and abnormal brain MRI findings. Persistence of fetal hemoglobin (HbF) has been identified in all patients tested. Growth delay, seizures, and autism spectrum disorder have been reported in some patients. Congenital malformations are present only in the individuals with 2p16.1 microdeletions that extend beyond the BCL11A gene.
Prevalence
The intellectual disability with persistence of fetal hemoglobin syndrome is a very rare and newly recognized condition. The prevalence is not known. Thirteen individuals with a point mutation and less than 30 patients with a deletion involving BCL11A have been reported in the literature thus far.
Inheritance
The intellectual disability with persistence of fetal hemoglobin syndrome, caused by a microdeletion or a mutation of BCL11A, is inherited in an autosomal dominant fashion. To date, all affected individuals result from a de novoBCL11A change (i.e. they are simplex cases), and no inherited cases have been reported. The recurrence risk for future pregnancies is low (probably <1%), but greater than that of the general population because of the possibility of germline mosaicism. Prenatal testing is theoretically feasible once the pathogenic variant is known.