The human Y and inactive X chromosomes similarly modulate autosomal gene expression

Somatic cells of human males and females have 45 chromosomes in common, including the "active" X chromosome. In males the 46th chromosome is a Y; in females it is an "inactive" X (Xi). Through linear modeling of autosomal gene expression in cells from individuals with zero to three Xi and zero to four Y chromosomes, we found that Xi and Y impact autosomal expression broadly and with remarkably similar effects. Studying sex chromosome structural anomalies, promoters of Xi- and Y-responsive genes, and CRISPR inhibition, we traced part of this shared effect to homologous transcription factors-ZFX and ZFY-encoded by Chr X and Y. This demonstrates sex-shared mechanisms by which Xi and Y modulate autosomal expression. Combined with earlier analyses of sex-linked gene expression, our studies show that 21% of all genes expressed in lymphoblastoid cells or fibroblasts change expression significantly in response to Xi or Y chromosomes.

The human Y and inactive X chromosomes similarly modulate autosomal gene expression

Somatic cells of human males and females have 45 chromosomes in common, including the "active" X chromosome. In males the 46th chromosome is a Y; in females it is an "inactive" X (Xi). Through linear modeling of autosomal gene expression in cells from individuals with zero to three Xi and zero to four Y chromosomes, we found that Xi and Y impact autosomal expression broadly and with remarkably similar effects. Studying sex-chromosome structural anomalies, promoters of Xi- and Y-responsive genes, and CRISPR inhibition, we traced part of this shared effect to homologous transcription factors - ZFX and ZFY - encoded by Chr X and Y. This demonstrates sex-shared mechanisms by which Xi and Y modulate autosomal expression. Combined with earlier analyses of sex-linked gene expression, our studies show that 21% of all genes expressed in lymphoblastoid cells or fibroblasts change expression significantly in response to Xi or Y chromosomes.

Reading Skills in Males with 47,XXY: Risk Factors and The Influence of Hormonal Replacement Treatment (HRT)

PURPOSE

47,XXY is often associated with reduced expressive language and literacy skills. This retrospective cross-sectional study investigated risk factors [hormone replacement deficiency, pre-or post-natal diagnosis, and history of family learning disabilities (FLD)] associated with reading skills in 152 males.

METHODS

We analyzed Woodcock Reading Mastery Test scores among seven prenatally diagnosed male HRT groups using analysis of variance along with Anova and two postnatally diagnosed male HRT groups (No-T and T) using t-tests. Treated, prenatally diagnosed males with FLD were compared to an identically treated prenatal HRT group with no history of FLD using a t-test.

RESULTS

In prenatally diagnosed males, significant treatment differences were observed on several reading scales (e.g., Total Reading: χ2 = 17.96, p = 0.006), where the highest modality HRT group (M =119.87) outperformed the untreated group (M = 99.88). In the postnatal analysis, we observed a significant effect of treatment on Basic Skills (p = 0.01). Despite equal HRT status, males with FLD (M = 105.79) exhibited reduced Total Reading skills compared to those (p32= 0.0006).

CONCLUSIONS

Our findings in this pilot study reveal that the most optimal reading trajectory is associated with a prenatal diagnosis, absence of FLD, and the highest modality HRT.

A longitudinal perspective of hormone replacement therapies (HRTs) on neuromotor capabilities in males with 47,XXY (Klinefelter syndrome)

PURPOSE

The purpose of this study was to delineate the effects of variable hormone replacement therapies on neuromotor function in a large cohort of males with 47,XXY from birth to adulthood.

METHODS

A total of 270 participants aged 16 days to 17 years 11 months prenatally diagnosed with 47,XXY were assessed by their pediatric endocrinologist and were administered hormone replacement therapies accordingly. Infants and school-aged children with 47,XXY were administered neuromotor assessments during routine neurodevelopmental evaluations. For statistical analysis, participants were segregated on the basis of treatment status. Two-tailed t tests, 1-way analysis of variance, and post hoc analysis determined significant group differences on each assessment.

RESULTS

In infants, the early hormonal treatment (EHT) group performed significantly better than the untreated group on fine motor and motor composite domains. In school-aged children, we observed significantly improved scores on fine motor control, coordination, agility, and strength domains among males treated with EHT (or any combination thereof) compared with those who did not receive early treatment.

CONCLUSION

The highest treated combination group was associated with the highest neuromotor function, although the EHT group also often performed better than the other groups. This suggests EHT may be essential in promoting long-term optimal neuromotor outcome in males with an additional X.

DNA methylation and behavioral dysfunction in males with 47,XXY and 49,XXXXY: a pilot study

Background

Equal dosage of X-linked genes between males and females is maintained by the X-inactivation of the second X chromosome in females through epigenetic mechanisms. Boys with aneuploidy of the X chromosome exhibit a host of symptoms such as low fertility, musculoskeletal anomalies, and cognitive and behavioral deficits that are presumed to be caused by the abnormal dosage of these genes. The objective of this pilot study is to assess the relationship between CpG methylation, an epigenetic modification, at several genes on the X chromosome and behavioral dysfunction in boys with supernumerary X chromosomes.

Results

Two parental questionnaires, the Behavior Rating Inventory of Executive Function (BRIEF) and Child Behavior Checklist (CBCL), were analyzed, and they showed expected differences in both internal and external behaviors between neurotypical (46,XY) boys and boys with 49,XXXXY. There were several CpGs in AR and MAOA of boys with 49,XXXXY whose methylation levels were skewed from levels predicted from having one active (Xa) and three inactive (Xi) X chromosomes. Further, methylation levels of multiple CpGs in MAOA showed nominally significant association with externalizing behavior on the CBCL, and the methylation level of one CpG in AR showed nominally significant association with the BRIEF Regulation Index.

Conclusions

Boys with 49,XXXXY displayed higher levels of CpG methylation at regulatory intronic regions in X-linked genes encoding the androgen receptor (AR) and monoamine oxidase A (MAOA), compared to that in boys with 47,XXY and neurotypical boys. Our pilot study results suggest a link between CpG methylation levels and behavior in boys with 49,XXXXY.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01123-4.

The incidence of anxiety symptoms in boys with 47,XXY (Klinefelter syndrome) and the possible impact of timing of diagnosis and hormonal replacement therapy

47,XXY (Klinefelter syndrome) is the most common X and Y chromosomal variation (1:660 males). The incidence of anxiety disorders and the impact of hormonal replacement therapy (HRT) is not well understood. Child Behavior Checklist and Screen for Childhood Anxiety Related Emotional Disorders were completed by parents of 80 boys with 47,XXY. Forty received HRT prior to 10 years of age while 40 did not. HRT (22.5%) received early hormonal treatment prior to 18 months. About 32.5% received hormone booster treatment between 5 and 10 years. The remaining 42.5% received both. There were fewer reported social (p = .015), thought (p = .012), and affective problems (p = .048) in treated boys when compared to untreated. Boys with both treatments demonstrated fewer symptoms on anxious/depressed scale (p = .001) compared to those with early treatment only. Within the treated group, prenatally diagnosed showed fewer indications of anxiety problems (p = .02) than their postnatal counterparts. This comparative, cross-sectional study expands previous findings on the possible positive effect of HRT in boys with 47,XXY. Anxiety disorders appear to be a penetrant aspect of the 47,XXY phenotype. Further investigation is warranted to explore the relationship between biological treatment and individual responses to HRT to develop more personalized and precise medicine.

The benefits and limitations of cell-free DNA screening for 47, XXY (Klinefelter syndrome)

OBJECTIVE

The purpose of this paper is to provide an overview of the 47, XXY syndrome, which is the most commonly occurring X and Y chromosomal variation. This paper seeks to review what is currently known of noninvasive prenatal testing (NIPT) and 47, XXY and investigate potential risks and benefits of prenatal identification.

METHOD

A literature review of NIPT and 47, XXY was performed to identify limitations of current NIPT techniques.

RESULTS

As NIPT becomes an increasingly more routine procedure, prenatal findings of 47, XXY may increase. Awareness of this disorder and appropriate genetic counseling is necessary.

CONCLUSION

X and Y chromosomal variations will be identified through this screening, and the benefits and limitations to this finding need to be thoughtfully considered. © 2017 John Wiley & Sons, Ltd.

Incidence of X and Y Chromosomal Aneuploidy in a Large Child Bearing Population

BACKGROUND

X&Y chromosomal aneuploidies are among the most common human whole-chromosomal copy number changes, but the population-based incidence and prevalence in the child-bearing population is unclear.

METHODS

This retrospective analysis of prospectively collected data leveraged a routine non-invasive prenatal test (NIPT) using parental genotyping to estimate the population-based incidence of X&Y chromosome variations in this population referred for NIPT (generally due to advanced maternal age).

RESULTS

From 141,916 women and 29,336 men, 119 X&Y chromosomal abnormalities (prevalence: 1 in 1,439) were identified. Maternal findings include: 43 cases of 45,X (40 mosaic); 30 cases of 47,XXX (12 mosaic); 3 cases of 46,XX uniparental disomy; 2 cases of 46,XY/46,XX; 23 cases of mosaicism of unknown type; 2 cases of 47,XX,i(X)(q10). Paternal findings include: 2 cases of 47,XXY (1 mosaic); 10 cases of 47,XYY (1 mosaic); 4 partial Y deletions.

CONCLUSIONS

Single chromosome aneuploidy was present in one of every 1,439 individuals considered in this study, showing 47,XXX; 47,XX,i(X)(q10); 47,XYY; 47,XXY, partial Y deletions, and a high level of mosaicism for 45,X. This expands significantly our understanding of X&Y chromosomal variations and fertility issues, and is critical for families and adults affected by these disorders. This current and extensive information on fertility will be beneficial for genetic counseling on prenatal diagnoses as well as for newly diagnosed postnatal cases.

Expanding the phenotypic profile of Kleefstra syndrome: A female with low-average intelligence and childhood apraxia of speech

Kleefstra syndrome (KS) is a rare neurogenetic disorder most commonly caused by deletion in the 9q34.3 chromosomal region and is associated with intellectual disabilities, severe speech delay, and motor planning deficits. To our knowledge, this is the first patient (PQ, a 6-year-old female) with a 9q34.3 deletion who has near normal intelligence, and developmental dyspraxia with childhood apraxia of speech (CAS). At 6, the Wechsler Preschool and Primary Intelligence testing (WPPSI-III) revealed a Verbal IQ of 81 and Performance IQ of 79. The Beery Buktenica Test of Visual Motor Integration, 5th Edition (VMI) indicated severe visual motor deficits: VMI = 51; Visual Perception = 48; Motor Coordination < 45. On the Receptive One Word Picture Vocabulary Test-R (ROWPVT-R), she had standard scores of 96 and 99 in contrast to an Expressive One Word Picture Vocabulary-R (EOWPVT-R) standard scores of 73 and 82, revealing a discrepancy in vocabulary domains on both evaluations. Preschool Language Scale-4 (PLS-4) on PQ's first evaluation reveals a significant difference between auditory comprehension and expressive communication with standard scores of 78 and 57, respectively, further supporting the presence of CAS. This patient's near normal intelligence expands the phenotypic profile as well as the prognosis associated with KS. The identification of CAS in this patient provides a novel explanation for the previously reported speech delay and expressive language disorder. Further research is warranted on the impact of CAS on intelligence and behavioral outcome in KS. Therapeutic and prognostic implications are discussed.

Positive effects of early androgen therapy on the behavioral phenotype of boys with 47,XXY

47, XXY occurs in up to 1 in 650 male births and is associated with androgen deficiency, neurodevelopmental delays, and atypical social-behaviors. Previously, we showed that young boys with 47, XXY who received early hormonal therapy (EHT) had significantly improved neurodevelopment. The objective of this follow-up study was to examine the effects of EHT on social behavior in boys with 47, XXY. The study consisted of boys prenatally diagnosed with 47, XXY who were referred for evaluations. Twenty-nine boys received three injections of 25 mg testosterone enanthate and 57 controls did not receive EHT. Behavioral functioning was assessed using the Behavior Rating Inventory of Executive Function, Social Responsiveness Scale, 2nd Ed., and the Child Behavior Checklist for Ages 6-18. The hypothesis that EHT may affect behavior was formulated prior to data collection. Questionnaire data was prospectively obtained and analyzed to test for significance between two groups. Significant differences were identified between group's scores over time in Social Communication (P=0.007), Social Cognition (P=0.006), and Total T-score (P=0.001) on the SRS-2; Initiation (P=0.05) on the BRIEF; and Externalizing Problems (P=0.024), Affective Problems (P=0.05), and Aggressive Behaviors (P=0.031) on the CBCL. This is the third study revealing positive effects of EHT on boys with XXY. There was a significant improvements associated with the 47, XXY genotype in boys who received EHT. Research is underway on the neurobiological mechanisms, and later developmental effects of EHT.

SNP-based non-invasive prenatal testing detects sex chromosome aneuploidies with high accuracy

OBJECTIVE

This study aimed to develop a single-nucleotide polymorphism-based and informatics-based non-invasive prenatal test that detects sex chromosome aneuploidies early in pregnancy.

METHODS

Sixteen aneuploid samples, including thirteen 45,X, two 47,XXY, and one 47,XYY, along with 185 euploid controls, were analyzed. Cell-free DNA was isolated from maternal plasma, amplified in a single multiplex polymerase chain reaction assay that targeted 19,488 polymorphic loci covering chromosomes 13, 18, 21, X, and Y, and sequenced. Sequencing results were analyzed using a Bayesian-based maximum likelihood statistical method to determine copy number of interrogated chromosomes, calculating sample-specific accuracies.

RESULTS

Of the samples that passed a stringent quality control metric (93%), the algorithm correctly identified copy number at all five chromosomes in all but one of the 187 samples, for 934/935 correct calls as early as 9.4 weeks of gestation. We detected 45,X with 91.7% sensitivity (CI: 61.5-99.8%) and 100% specificity (CI: 97.9-100%), and 47,XXY and 47,XYY. The average calculated accuracy was 99.78%.

CONCLUSION

This method non-invasively detected 45,X, 47,XXY, and 47,XYY fetuses from cell-free DNA isolated from maternal plasma with high calculated accuracies and thus offers a non-invasive method with the potential to function as a routine screen allowing for early prenatal detection of rarely diagnosed yet commonly occurring sex aneuploidies.

Prenatal diagnosis and 47,XXY

In this contribution, we consider detection of 47,XXY by a variety of available methods. These include traditional invasive procedures, screening with maternal serum analytes and fetal ultrasound, and most recently cell-free fetal DNA. Since its introduction in the late 1960s, prenatal genetic diagnosis has evolved greatly. Serendipitious detection of 47,XXY was not infrequent when prenatal genetic diagnosis routinely involved testing by the invasive procedures CVS and amniocentesis. In 2013 this is much less common and relatively few pregnancies in the U.S. and Europe are tested without prior screening protocols, traditionally maternal serum analyte and fetal ultrasound (NT). These protocols are not designed to identify 47,XXY or other X-chromosome aneuploides and with screening by analysis of cell-free DNA in maternal blood, this situation may or may not be altered. Increased numbers of cases could be detected if intake increases and vendors offer information on 47,XXY. A further consideration is that ability of array CGH to detect microdeletions or microduplications below resolution of a karyotype could make return to direct testing using an invasive procedure attractive.

Immunodeficiency in patients with 49,XXXXY chromosomal variation

Boys affected with 49,XXXXY sex chromosomal variation have been described to have high incidence of recurrent otitis media and asthma, the cause of which is unknown. We hypothesized that primary immunodeficiency occurs in patients with XXXXY aneuploidy. To investigate this, 31 boys with known 49,XXXXY were evaluated through a multidisciplinary clinic. Screening history was performed using the "10 Warning Signs of primary immunodeficiency" (Jeffrey Modell Foundation), as well as by history of atopic and autoimmune conditions. Of the 31 boys, 20 had at least two warning signs of primary immunodeficiency, and five had four or more signs. Sixteen had history of recurrent pneumonia, and 15 carried the diagnosis of asthma. Of the 10 who underwent immunologic screening, eight showed some evidence of impaired antibody responses to polysaccharide antigens, and one was diagnosed with specific antibody deficiency. These preliminary results suggest a high incidence of both atopy and antibody deficiency in boys with 49,XXXXY.

Expansion of the phenotypic profile of the young child with XXY

XXY is a common chromosomal abnormality which remains under diagnosed and not well understood, although it was first described more than 50 years ago. In the last ten years, with advancement in neuroimaging technology and the greater understanding of behavioral neurogenetics, there has been a resurgence of interest in children and adults with XXY. This homogenous population provides insight into the interaction between learning dysfunction, brain development and behavioral performance that may be investigated from birth onward. The unique attributes of the child from birth to 6 years of age with XXY is discussed in this paper. This paper postulates a novel reconceptualization of the phenotypic presentation of the boys with XXY. The neurodevelopmental profile of XXY is actually quite consistent over time with the common thread of speech and language deficits, motor dysfunction and frontal lobe deficits including attention, planning and organization. The early motor and speech disturbances are not random developmental delays, but rather the early presentation of the central nervous system dysfunction associated with XXY. Muscle tonus abnormalities are present in trunk, upper extremities and oral facial musculature in more than 80% of the infants with XXY.Androgen deficiency may be an integral part of the delays observed in boys with XXY, since androgen is influential in brain organization, neurobehavioral development, temperament and mood in humans. It is plausible that the earliest biomarker for androgen deficiency in XXY may be the decreased muscle tonus. Androgen deficiency may not be the only causative factor in the neurodevelopmental disturbance in individuals with XXY, but may promote a restorative function if timing and dosage is appropriate. The study of children with XXY offers an opportunity to observe the impact of the genetic and chromosomal influence on learning and behavior in a population with great homogeneity. XXY is a multifaceted spectrum disorder which demonstrates the complexity of the relationship between brain, behavior, genes and the environment.

Effect of ascertainment and genetic features on the phenotype of Klinefelter syndrome

OBJECTIVE

To describe the Klinefelter Syndrome (KS) phenotype during childhood in a large cohort.

STUDY DESIGN

Clinical assessment, measurement of hormonal indices of testicular function, and parent of origin of extra X chromosome were assessed in a cross-sectional study of 55 boys with KS, aged 2.0 to 14.6 years, at an outpatient center.

RESULTS

Mean height and body mass index SD scores (SDS +/- SD) were 0.9 +/- 1.3 and 0.4 +/- 1.4, respectively. Mean penile length and testicular volume SDS were -0.5 +/- 0.9 and -0.9 +/- 1.4. Testosterone levels were in the lowest quartile of normal in 66% of the cohort. Other features included clinodactyly (74%), hypertelorism (69%), elbow dysplasia (36%), high-arched palate (37%), hypotonia (76%), and requirement for speech therapy (69%). Features were similar in boys in whom the diagnosis was made prenatally versus boys in whom the diagnosis was made postnatally. There was no evidence for a phenotypic effect of parent of origin of the extra X chromosome.

CONCLUSIONS

Boys with KS commonly have reduced penile length and small testes in childhood. The phenotype in boys with KS does not differ according to ascertainment or origin of the extra X chromosome. Boys with KS may be identified before puberty by tall stature, relatively decreased penile length, clinodactyly, hypotonia, and requirement for speech therapy.

Androgen receptor CAGn repeat length influences phenotype of 47,XXY (Klinefelter) syndrome

CONTEXT

Klinefelter syndrome (KS; 47,XXY karyotype and variants) is characterized by tall stature and testicular failure, with marked variation in severity of the phenotype. Previous studies have proposed that genetic factors including mosaicism, parental origin of the supernumerary X-chromosome, skewed X inactivation, and androgen receptor (AR) polyglutamine repeat length may contribute to phenotypic variability in KS.

OBJECTIVE

The objective of this study was to investigate the roles of these genetic factors in the variability of the KS phenotype.

DESIGN

This was a cross-sectional study.

SETTING

The study was performed at a pediatric endocrinology referral clinic.

PATIENTS

Thirty-five KS boys and men, aged 0.1-39 yr, were studied.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURES

Auxological measurements, biological indices of testicular function, and clinical assessment of muscle tone were the main outcome measures. Genetic studies included karyotyping to detect mosaicism, genotyping of microsatellite markers to determine parental origin of the supernumerary X-chromosome, and genotyping and methylation studies to measure AR polyglutamine (AR CAGn) repeat length and X inactivation ratio.

RESULTS

The only genetic factor that significantly influenced the KS phenotype was the AR CAGn repeat length, which was inversely correlated with penile length, a biological indicator of early androgen action. Mosaicism, imprinting, and skewed X inactivation did not account for the variability of the KS phenotype.

CONCLUSIONS

Normal genetic variation in the AR coding sequence may be clinically significant in the setting of early testicular failure and subnormal circulating testosterone levels, as occur in KS.

Early androgen deficiency in infants and young boys with 47,XXY Klinefelter syndrome

BACKGROUND/AIMS

Klinefelter syndrome (KS) is characterized by the karyotype 47,XXY. In this study, we evaluated the physical and testicular failure phenotypes of infants and young boys with KS.

METHODS

The evaluation included auxologic measurements, biologic indices of testicular function, and clinical assessment of muscle tone in 22 infants and young boys with KS, ages 1-23 months.

RESULTS

Mean length, weight, and head circumference in SDS were generally within the normal range at -0.3 +/- 1.0, -0.1 +/- 1.4, and 0.0 +/- 1.5, respectively. Mean penile length and testicular volume SDS were -0.9 +/- 0.8 and -1.1 +/- 0.8, indicating significantly reduced penile and testicular size. Mean testosterone levels for the boys < or =6 and >6-23 months were 128 +/- 131 (4.4 +/- 4.5 nmol/l) and 9.5 +/- 7.2 ng/dl (0.3 +/- 0.2 nmol/l), respectively. High-arched palate was observed in 6/17 boys and clinodactyly (5th finger) was observed in 15/16 boys. Hypotonia was evaluated clinically and was noted to be present in 12/17 boys.

CONCLUSION

The physical phenotype in infants and young boys with KS (1-23 months old) includes normal auxologic measurements and early evidence of testicular failure. Muscle tone was decreased in most of the boys. Testicular volume and penile length were diminished, indicating early androgen deficiency. The neonatal surge in testosterone was attenuated in our KS population. Thus, infants and young boys with KS have evidence of early testicular failure. The etiology of this failure and the clinical role of early androgen replacement require further study.

Outcome measures for clinical drug trials in autism

This paper identifies instruments and measures that may be appropriate for randomized clinical trials in participants with autism spectrum disorders (ASDs). The Clinical Global Impressions scale was recommended for all randomized clinical trials. At this point, however, there is no "perfect" choice of outcome measure for core features of autism, although we will discuss five measures of potential utility. Several communication instruments are recommended, based in part on suitability across the age range. In trials where the intention is to alter core features of ASDs, adaptive behavior scales are also worthy of consideration. Several "behavior complexes" common to ASDs are identified, and instruments are recommended for assessment of these. Given the prevalence of cognitive impairment in ASDs, it is important to assess any cognitive effects, although cognitive data from ASD randomized clinical trials, thus far, are minimal. Guidance from trials in related pharmacologic areas and behavioral pharmacology may be helpful. We recommend routine elicitation of side effects, height and weight, vital signs, and (in the case of antipsychotics) extrapyramidal side-effects assessment. It is often appropriate to include laboratory tests and assessments for continence and sleep pattern.

Klinefelter syndrome: Expanding the phenotype and identifying new research directions

PURPOSE

The purpose of this study is to summarize new data on etiology and clinical features of Klinefelter syndrome in order to derive research priorities.

METHODS

This study was conducted using critical reviews of selective topics, emphasizing less well-recognized clinical findings.

RESULTS AND CONCLUSIONS

The phenotype of the prototypic 47,XXY case is well recognized: seminiferous tubule dysgenesis and androgen deficiency. Less well appreciated is the varied expressivity of 47,XXY Klinefelter syndrome, in particular neurological/cognitive perturbations like language and behavioral problems. Effective therapies are available. Reproductive technologies allow 47,XXY men to sire offspring through intracytoplasmic sperm injection (ICSI); however, genetic counseling is complex and success is low. Behavioral and expressive language difficulties are amenable to treatment by androgen therapy and psychological help. Early treatment may be imperative for optimal outcome.

Mental development in polysomy X Klinefelter syndrome (47,XXY; 48,XXXY): effects of incomplete X inactivation

The child with XXY or a variant form is a fertile ground for scientific investigation because of the homogeneity of the disorder and the increased prevalence of learning disorders associated with it. However, the research studies of boys with XXY (Klinefelter syndrome) have been plagued by a variety of factors from small sample size, methodological flaws, and ascertainment bias. In spite of these shortcomings, there remains some consistency to the neurobehavioral profile of this disorder. In general, the prenatal population of boys with XXY is less affected developmentally and is more academically successful than the boys identified through postnatal diagnosis. Boys with XXY often have decreased muscle tonus, delayed speech, and language skills with an increased incidence of reading differences and dyslexia. It does appear that social difficulties may be mediated by language processing problems and temperamental issues. The neurobehavioral and neurocognitive phenotype of boys with XXY places them at risk for school failure and secondary behavioral disturbances. Therefore, early evaluation and intervention is strongly recommended since the prognosis may be improved significantly with appropriate therapeutic intervention. The natural history of this disorder is not well defined from the neurodevelopmental, neuroimaging, and cytogenetic perspective. Further investigation into the effects and the relationships between parental origin and outcome may provide many answers regarding the variability of the disorder. Lastly, some promising theories have been postulated regarding the neurobiological etiology of this disorder, which requires more investigation if we are to understand the pathogenesis of this XXY and its effect on learning.

Developmental concerns in children with congenital heart disease

Neurodevelopmental outcome of children with congenital heart disease includes a wide spectrum of developmental disorders from language and learning disabilities to mental retardation, delayed development, and cerebral palsy. Numerous studies of cardiopulmonary bypass show that this procedure alone does not affect IQ, but length of circulatory arrest and pH management are associated with decreased IQ. Described here is a behavioral phenotype of children with cardiac disease with a low normal IQ and perceptual-motor delays who are temperamentally more difficult. Further investigation of the vulnerability of specific cardiac lesions, mode of treatment, and the behavioral phenotype of children with congenital heart disease along with the influences of family functioning, socioeconomic status, and chronic medical care is warranted.

Neurodevelopmental outcome of infant cardiac transplant recipients

Normal growth and development are indicators of the success of infant cardiac transplantation. The clinical transplant coordinator must be aware of age-appropriate milestones in gross motor, fine motor, language, cognitive, and social skills, so that accurate assessment and early intervention can be instituted. In this review of five cases, gross motor development was the only category with consistently lower scores. Gross motor development did improve in the two cases tested more than once. Length of hospitalization before and after transplantation and use of sedative medications during the waiting period may have affected developmental outcome scores.