Familial occurrence of a syndrome with mental retardation,nasal hypoplasia,peripheral dysostosis,and blue eyes in Japanese siblings

Summary Two Japanese siblings, a 2-year-old girl and a 7-month-old boy, had a syndrome of mental retardation, severe nasal hypoplasia, peripheral dysostosis, and blue eyes. The mother showed nasal hypoplasia of lesser degree and a mild form of peripheral dysostosis. This disorder bears a striking similarity to acrodysostosis, but in view of certain novel features its relationship to the disease is uncertain. The mode of inheritance could be either dominant with variable expressivity or autosomal recessive.     

46XY siblings with inadequate virilization and CNS deficiency

Familial expression of inadequate virilization of 46XY siblings is often reported as an isolated anomaly. We recently evaluated two families with 2 siblings who had a 46XY karyotype, ambiguous genitalia or micropenis, facial anomalies and mental retardation. There is no evidence of gonadotropin deficiency, defects of steroidogenesis, or androgen insensitivity. While there was a testosterone response to human chorionic gonadotropin stimulation in all 3 tested, gonadotropin levels were elevated in 2 of the infants suggestive of faulty seminiferous tubules, 1 of whom later had elevated luteinizing hormone levels. These kindreds may represent a new syndrome with either an X-linked recessive or sex-limited autosomal dominant form of inheritance, with partial testicular failure, multiple congenital anomalies, and mental retardation.     

Costello syndrome in two siblings and minor manifestations in their mother. Further evidence for autosomal dominant inheritance?

We report on two siblings: the index patient, a 9 months old boy and his 2.5 years old sister, both presenting the main clinical signs and symptoms of Costello syndrome (CS): severe mental and motor retardation, feeding difficulties, failure to thrive in the first months of life, coarse facial appearance, skin hyperlaxity and skeletal deformities. Their mother presented with mild to moderate mental retardation, short stature, facial fullness and wart-like lesions on her face. The present observation confirms previous data on the apparent autosomal dominant pattern of inheritance in Costello syndrome with variable expression.     

Defects of skeletal morphology, density, and structure in mouse fetuses with trisomy 16

Skeletal anomalies present in trisomy 16 in the mouse--an animal model of human trisomy 21--are described. Altogether 27 fetuses with trisomy 16 and 118 chromosomally balanced siblings were examined radiographically and by alizarin staining on day 20 of gestation; the radiographs were analyzed by computer-aided densitometry and structural differentiation. Extensive asymmetry or abnormal fusion of the vertebral centers and alterations of the vertebral arches were observed along with rib malformations (rib-vertebra syndrome). The skull primarily exhibited anomalies of the occipital bone. Ossification of the humerus, femur, and tibia was characterized by reduced mineralization. Typical, fracture-like alterations affecting only the tibia were also observed. Measurement of the lengths of the humeri of fetuses of comparable weight revealed a growth retardation not correlatable with the degree of mineralization. The significance of these skeletal abnormalities with regard to the trisomy 21 syndrome is discussed.     

Double aneuploidy: partial trisomy 21 and XO/XXX in a family with 12/21 translocation.

A female patient with mild mental retardation with spatial perceptual difficulties, microcephaly, depressed nasal root, receding chin, webbed neck, low hairline, shield chest, cubitus valgus, scoliosis and dermatoglyphic findings not characteristic of Down's syndrome is reported. In addition to X/XXX, she had a partial trisomy 21 of the short arm-centromere-proximal long arm segment due to maternal t(12;21) translocation. Two phenotypically normal siblings carried the balanced translocation.     

SLC9A6 mutations cause X-linked mental retardation, microcephaly, epilepsy, and ataxia, a phenotype mimicking Angelman syndrome

Linkage analysis and DNA sequencing in a family exhibiting an X-linked mental retardation (XLMR) syndrome, characterized by microcephaly, epilepsy, ataxia, and absent speech and resembling Angelman syndrome, identified a deletion in the SLC9A6 gene encoding the Na(+)/H(+) exchanger NHE6. Subsequently, other mutations were found in a male with mental retardation (MR) who had been investigated for Angelman syndrome and in two XLMR families with epilepsy and ataxia, including the family designated as having Christianson syndrome. Therefore, mutations in SLC9A6 cause X-linked mental retardation. Additionally, males with findings suggestive of unexplained Angelman syndrome should be considered as potential candidates for SLC9A6 mutations.     

A novel 7.4 kb mitochondrial deletion in a patient with congenital progressive external ophthalmoplegia, muscle weakness and mental retardation.

We present a patient with external ophthalmoplegia, bilateral ptosis, progressive muscle weakness with "ragged-red fibres" and mental retardation. Mitochondrial DNA analysis by Southern blot revealed heteroplasmy in muscle for a 7.4 kb deletion. In white blood cells, the deletion was only detectable by PCR. There was no evidence for duplications, nor for multiple deletions in the proband or siblings. PCR analysis did not reveal the presence of a mitochondrial DNA defect in the parents and siblings. Thus, there is no experimental support for a maternally inherited mitochondrial DNA deletion. We consider this a sporadic case with a de novo deletion. Diabetes and complaints of fatigue, also seen in this family, are probably coincidental. Mental retardation has been reported occasionally in patients with mitochondrial deletions, but is not common.     

The relationship between IGF-I concentration, cognitive function and quality of life in adults with Prader-Willi syndrome

Mental retardation is one of the clinical characteristics of Prader-Willi syndrome (PWS) and in part of the patients growth hormone deficiency is demonstrable. Cognitive function seems to be influenced by insulin-like growth factor I (IGF-I); however, little is known about cognitive function in relation to IGF-I levels in PWS adults. The aim of the present study was to evaluate cognitive function in adult PWS patients in comparison to healthy siblings and to investigate whether there is a correlation between cognitive function and IGF-I levels. Anthropometric measurements, IGF-I levels, quality of life (QoL), Appetite Assessment Score, IQ (GIT and Raven) and cognitive function (by four subtests of the Cambridge Neuropsychological Automated Testing Battery, CANTAB) were evaluated in PWS patients and their healthy siblings served as control group. PWS patients had significantly lower IGF-I levels, IQ and QoL when compared to controls. Reaction times were longer and performance was worse on CANTAB subtests in PWS adults. IGF-I on one hand and IQ, Appetite Assessment Score and cognitive performance on the other hand seem to be correlated in PWS patients. In conclusion, IGF-I levels, IQ and QoL are significantly lower in PWS subjects when compared to healthy siblings. In PWS adults, temporal as well as prefrontal cognitive functions are impaired. Higher IGF-I levels appear to be related to better intellectual skills and faster temporal memory processing in PWS patients.     

Siblings with chromosome mosaicism,microcephaly, and growth retardation: the phenotypic expression of a human mitotic mutant?

Summary We report male and female siblings with extreme microcephaly and mental retardation, growth retardation, and multiple chromosome mosaicism. Mental retardation associated with chromosome mosaicism does not always carry a low recurrence risk.     

The Coffin-Lowry Syndrome-Associated Protein rsk2 and Neurosecretion

Coffin-Lowry syndrome (CLS) is a syndromic form of X-linked mental retardation, characterized in male patients by psychomotor and growth retardation and various skeletal anomalies. CLS is caused by mutations in the RPS6KA3 gene, which encodes RSK2, a growth factor-regulated protein kinase. Cognitive deficiencies in CLS patients are prominent, but markedly variable in severity, even between siblings. However, the vast majority of patients are severely affected, with mental retardation ranging from moderate to profound. We used a RSK2-KO mouse model that shows no obvious brain abnormalities at the anatomical and histological levels to study the function of RSK2 in neurosecretion. Behavioral studies revealed normal motor coordination, but a profound retardation in spatial learning and a deficit in long-term spatial memory, providing evidence that RSK2 plays similar roles in mental functioning both in mice and human. We found that associative LTP at cortical inputs to the lateral amygdala was blocked in Rsk2 KO mice. Using an RNA interference rescue strategy in PC12 cells, we were able to demonstrate that RSK2 regulates catecholamine release through the phosphorylation of PLD. These results provide the first molecular evidence that RSK2 could regulate neurotransmitter release by activating PLD production of lipids required for exocytosis.     

Microencephalic nanism, severe retardation, hypertonia, obesity, and hypogonadism in two brothers: a new syndrome?

Two brothers are described with a severe syndrome of postnatal growth and mental retardation which includes extreme microcephaly, obesity developing during infancy, microgonadismsm, and a characteristic amphora-shaped facies. The neurological exam is highly abnormal, with hypertonia and hyperreflexia, nystagmus, and an extremely irritable and agitated behavior. The first child, who died at 4/1/2 years, also presented neonatal hypoglycemia and chronic constipation. Although the etiology of this syndrome is unknown, it is tempting to consider an X-linked recessive gene, given the importance of the X chromosome in mental retardation. Among the over 70 syndromes of X-linked mental retardation already described, our patients resemble individuals with the B?rjeson-Forssman-Lehmann (BFL) syndrome the most. However, the severity of their dwarfism and mental retardation is much greater than described in any BFL patient to date, and the neurological and dysmorphic features vary significantly from those described in the BFL. Although a particularly severe variant, perhaps allelic, is a possibility, an as yet undescribed disorder is also plausible, the etiology of which would probably be recessive, either autosomal or X-linked.     

Moderate Down's syndrome in three siblings having partial trisomy 21q22.2→qter and therefore no SOD-1 excess

Summary Three mentally retarded siblings with moderate stigmata of Down's syndrome were found to have a partial trisomy 21q22.2qter resulting from a maternal translocation t(4q+;21q-). By the exclusion of any excess of SOD-1 in them, we can confirm the nonessentiality of the sub-band 21q22.1 and of the SOD-1 excess for most of the Down's syndrome stigmata including the mental retardation. However, the sub-band 21q22.1 in triplicate might be required for the completion of the full syndrome, as for example is shown by the incomplete dermatoglyphic pattern on the palms in the patients.     

Mohr syndrome in two siblings

The present study reports on two siblings of different sex, affected with a condition corresponding to Mohr syndrome. Characteristic symptoms such as epicanthic folds, a broad and flattened nasal root, a lobulated and hamartomatous tongue, poly- and syndactyly on both hands and feet, doubling of the big toes with less frequent features such as marked psychosomatic retardation and overall hypotony have been observed. All the cited anomalies have been of importance in the differential diagnosis. Difficulties associated with classification of new syndromes and the importance for practical clinical genetics of distinguishing between them are discussed.     

Calmodulin Methyltransferase Is Required for Growth,Muscle Strength,Somatosensory Development and Brain Function

Calmodulin lysine methyl transferase (CaM KMT) is ubiquitously expressed and highly conserved from plants to vertebrates. CaM is frequently trimethylated at Lys-115, however, the role of CaM methylation in vertebrates has not been studied. CaM KMT was found to be homozygously deleted in the 2P21 deletion syndrome that includes 4 genes. These patients present with cystinuria, severe intellectual disabilities, hypotonia, mitochondrial disease and facial dysmorphism. Two siblings with deletion of three of the genes included in the 2P21 deletion syndrome presented with cystinuria, hypotonia, a mild/moderate mental retardation and a respiratory chain complex IV deficiency. To be able to attribute the functional significance of the methylation of CaM in the mouse and the contribution of CaM KMT to the clinical presentation of the 2p21deletion patients, we produced a mouse model lacking only CaM KMT with deletion borders as in the human 2p21deletion syndrome. No compensatory activity for CaM methylation was found. Impairment of complexes I and IV, and less significantly III, of the mitochondrial respiratory chain was more pronounced in the brain than in muscle. CaM KMT is essential for normal body growth and somatosensory development, as well as for the proper functioning of the adult mouse brain. Developmental delay was demonstrated for somatosensory function and for complex behavior, which involved both basal motor function and motivation. The mutant mice also had deficits in motor learning, complex coordination and learning of aversive stimuli. The mouse model contributes to the evaluation of the role of methylated CaM. CaM methylation appears to have a role in growth, muscle strength, somatosensory development and brain function. The current study has clinical implications for human patients. Patients presenting slow growth and muscle weakness that could result from a mitochondrial impairment and mental retardation should be considered for sequence analysis of the CaM KMT gene.     

A girl with the Prader-Willi Syndrome and Robertsonian translocation 45,XX,t(14;15)(p11;q11) which was present in three normal family members

Summary A 21-year-old girl with classical Prader-Willi Syndrome was found to have a 14;15 Robertsonian translocation—45,XX,t(14;15)(p11;q11). This type of Robertsonian translocation was not found in any patient from 8 surveys covering 6144 patients with mental retardation. Chromosome 15 has been involved in translocations in patients with the Prader-Willi Syndrome with greater than expected frequency. This is the first report of a 14;15 translocation and the Prader-Willi Syndrome. The same balanced translocation was present in the patient's mother and 2 normal siblings. Future genetic counselling for these 2 siblings will be difficult.     

Further delineation of renal-coloboma syndrome in patients with extreme variability of phenotype and identical PAX2 mutations.

Renal-coloboma syndrome is a recently described autosomal dominant syndrome of abnormal optic nerve and renal development. Two families have been reported with renal-coloboma syndrome and mutations of the PAX2 gene. The PAX2 gene, which encodes a DNA-binding protein, is expressed in the developing ear, CNS, eye, and urogenital tract. Ocular and/or renal abnormalities have been consistently noted in the five reports of patients with renal-coloboma syndrome, to date, but PAX2 expression patterns suggest that auditory and CNS abnormalities may be additional features of renal-coloboma syndrome. To determine whether additional clinical features are associated with PAX2 mutations, we have used PCR-SSCP to identify PAX2 gene mutations in patients. We report here four patients with mutations in exon 2, one of whom has severe ocular and renal disease, microcephaly, and retardation, and another who has ocular and renal disease with high-frequency hearing loss. Unexpectedly, extreme variability in clinical presentation was observed between a mother, her son, and an unrelated patient, all of whom had the same PAX2 mutation as previously described in two siblings with renal-coloboma syndrome. These results suggest that a sequence of seven Gs in PAX2 exon 2 may be particularly prone to mutation.     

A syndrome of congenital ichthyosis, hypogonadism, small stature, facial dysmorphism, scoliosis and myogenic dystrophy

Rud syndrome formerly was considered as a genetically heterogeneous but distinct clinical entity with the manifestations of ichtyosis, hypogonadism, small stature, mental retardation, epilepsy and, infrequently, retinitis pigmentosa. The existence of such a syndrome has recently been dismissed based on a new understanding of the ichthyoses. We report on the clinical history of a 14-year-old boy with congenital ichthyosis, small stature, hypogonadism, facial dysmorphism, nystagmus, kypho-scoliosis and myogenic dystrophy. He was diagnosed as Rud syndrome but developed neither seizures nor mental retardation. However a cousin was mentally retarded. The ichthyosis was familial as five relatives had ichthyosis but no other features of Rud syndrome. The patient had a deletion of the steroid-sulfatase gene. He had neither chondrodysplasia punctata, nor Kallmann syndrome, two conditions which are part of the contiguous gene syndrome of the Xp22.3 region. Most case reports previously reported as Rud syndrome can now be reassigned under a contemporary ichthyosis classification that does not include Rud syndrome as a distinct entity. This case was clearly distinct from Refsum disease, Sj?gren-Larsson syndrome and any of the other ichthyosis disorders that have been suggested as a replacement for Rud syndrome. Thus the case reported here appears distinct from any previously described, currently recognized syndrome.     

Barth syndrome: cardiolipin,cellular pathophysiology,management, and novel therapeutic targets

Molecular and Cellular Biochemistry - Barth syndrome is a rare X-linked genetic disease classically characterized by cardiomyopathy, skeletal myopathy, growth retardation, neutropenia, and...     

Down syndrome in two siblings with 47,XY,+21 and 46,XY/46,XY,-21,+t(21q;21q)

Summary This is the first report in the literature of siblings affected with Down syndrome; one sibling had a nondisjunction of chromosome 21 and the other a (21q;21q) translocation.