MedGen

Nonspecific X-linked intellectual deficiencies (MRX) belong to the family of sex-linked intellectual deficiencies (XLMR). In contrast to syndromic or specific X-linked intellectual deficiencies (MRXS), which also present with associated physical, neurological and/or psychiatric manifestations, intellectual deficiency is the only symptom of MRX. [from MONDO]

A mode of inheritance that is observed for traits related to a gene encoded on the X chromosome. [from HPO]

An X-linked dominant condition caused by mutation(s) in the IQSEC2 gene, encoding IQ motif and SEC7 domain-containing protein 2. It is characterized by substantially impaired intellectual functioning and behavioral abnormalities. [from NCI]

Any non-syndromic X-linked intellectual disability in which the cause of the disease is a mutation in the ARHGEF6 gene. [from MONDO]

An X-linked syndromic intellectual disability characterised by severe intellectual disability, microcephaly and short stature in male patients. Strabismus and spastic diplegia have also been described. [from ORDO]

X-linked intellectual disability, Wilson type is characterised by severe intellectual deficit with mutism, epilepsy, growth retardation and recurrent infections. It has been described in three males from three generations of one family. The causative gene has been localised to the 11p region of the X chromosome. [from ORDO]

X-linked intellectual developmental disorder-9 (XLID9) is characterized by moderately to severely impaired intellectual development. Some patients have also been reported with delayed motor development, seizures, and/or behavioral problems (Hamel et al., 1999; Froyen et al., 2007). [from OMIM]

A rare genetic syndromic intellectual disability characterised by mild to severe intellectual disability associated with variable features, including hypotonia, dyskinesia, spasticity, wide-based gait, microcephaly, epilepsy and behavioural problems. MRI imaging may show a corpus callosum hypoplasia or ventricular enlargement. Other variable features such as joint hyperlaxity, skin pigmentary abnormalities and visual impairment have also been reported. [from SNOMEDCT_US]

X-linked intellectual disability-cubitus valgus-dysmorphism syndrome is characterised by moderate intellectual deficit, marked <i>cubitus valgus</i>, mild microcephaly, a short philtrum, deep-set eyes, downslanting palpebral fissures and multiple nevi. Less than ten individuals have been described so far. Transmission is thought to be X-linked recessive. [from ORDO]

A rare genetic intellectual disability characterized by the association of intellectual disability with variable other anomalies in the absence of a well-characterized syndrome. Associated abnormalities may include facial dysmorphism, neurological signs and symptoms, behavioral problems, and abnormalities of various other organ systems. [from SNOMEDCT_US]

NEDDFL is a neurodevelopmental disorder characterized by delayed psychomotor development and impaired intellectual development, poor growth with small head size, dysmorphic facial features, and mild abnormalities of the hands and feet (summary by Stankiewicz et al., 2017). [from OMIM]

This syndrome has characteristics of ataxia, apraxia, intellectual deficit and or seizures. It has been described in nine males in two unrelated Danish families. It is transmitted as an X-linked recessive syndrome with partial clinical expression in obligate female carriers. [from SNOMEDCT_US]

This syndrome is characterized by severe intellectual deficit, acromegaly and hyperactivity. The syndrome has been described in two half-brothers. Dysarthria, aggressive behavior, a characteristic facies (an acromegalic and triangular face with a long nose) and macroorchidism were also present. The mother displayed moderate intellectual deficit and milder facial anomalies. Central nervous system anomalies were identified in the two boys: subarachnoid cysts and hyperdensity in the pontine region. [from SNOMEDCT_US]

This syndrome has characteristics of severe intellectual deficit, brachycephaly, plagiocephaly, prominent forehead and coarse facial features. It has been described in two males from one family. Two females belonging to the same family displayed moderate intellectual deficit but no craniofacial dysmorphism. [from SNOMEDCT_US]

X-linked intellectual disability-craniofacioskeletal syndrome is a rare, hereditary, syndromic intellectual disability characterized by craniofacial and skeletal abnormalities in association with mild intellectual disability in females and early postnatal lethality in males. In addition to mild cognitive impairment, females present with microcephaly, short stature, skeletal features and extra temporal lobe gyrus. In males, intrauterine growth impairment, cardiac and urogenital anomalies have been reported. [from ORDO]

Impaired mental functioning occurs as an isolated feature or as part of many syndromes listed in the X-linked catalog. Impaired intellectual development that is not associated with other distinguishing features is referred to as 'nonspecific.' The Human Gene Mapping Nomenclature Committee (Mulley et al., 1992) proposed to designate each newly reported apparently unique X-linked mental retardation (MRX) family with gene symbols (e.g., MRX1, MRX2) if a minimal lod score of 2.0 was demonstrated between the MR locus and one or more X chromosome markers. [from OMIM]