Rafiq et al. (2010) reported 3 consanguineous Pakistani families with nonsyndromic mental retardation. The patients were severely mental retarded, all but 1 with an IQ less than 40 and all with delayed speech. Two of 3 sibs in ... Rafiq et al. (2010) reported 3 consanguineous Pakistani families with nonsyndromic mental retardation. The patients were severely mental retarded, all but 1 with an IQ less than 40 and all with delayed speech. Two of 3 sibs in 1 family had truncal obesity, and 2 other patients had epilepsy. None had microcephaly or autistic features. The families belonged to the same clan and were from the same village. Rafiq et al. (2011) provided follow-up of these families, who were from the Punjab province. Two patients had delayed psychomotor development and began walking at age 4 years. Both had hyperphagia and were overweight. Some patients achieved speaking in sentences and toilet training; aggression was a common feature. Mild dysmorphic features, such as dolichocephaly, downslanted palpebral fissures, broad nose, and small chin, were noted. Rafiq et al. (2011) reported another consanguineous Pakistani family from the Sindh province with a similar, but less severe, form of intellectual disability. In addition to mental retardation, these patients showed dysmorphic features, including downslanting palpebral fissures, hypertelorism, long face, flattened malar region, short philtrum, broad nasal root, and small chin. Rafiq et al. (2011) also described 3 members of an Iranian family with nonsyndromic mental retardation. Overall intellectual disability varied, with 1 patient able to speak and count money and the others more severely affected. Seizures were variable. Dysmorphic features were mild and variable, but included dolichocephaly, long face, flat philtrum, downslanting palpebral fissures, hypertelorism, thin upper lip, triangular and pointed chin, and prominent nose.
In affected members of 5 families with autosomal recessive mental retardation-15, Rafiq et al. (2011) identified 3 different homozygous mutations in the MAN1B1 gene (604346.0001-604346.0003).