The subject was born in Guayaquil, Ecuador, at 36 weeks of gestation by vaginal delivery. His weight was 2.5 kg, length was 46 cm, and head circumference was 35.5 cm (normal values for gestational age). The mother did not report complications during the pregnancy; she was 23 years old at the subject’s birth. The father has been diagnosed with severe hemophilia A, and no other family members reported to be affected by any other disease (Fig. 1).
At the time of birth, the subject presented a hematoma in the forehead, which, based on the father’s diagnosis of hemophilia, raised doubts about the child status. At 3 months old, the Factor VIII activity measure showed a 23.7% activity indicating a diagnosis of mild hemophilia A. Moreover, a Factor V activity test was performed, showing normal ranges of activity, rejecting a diagnosis of hemophilia B. At 5 years old, the Factor VIII activity was measured again, showing a 38.8% activity and 0.00 Bethesda Units/mL of Factor VIII inhibitor. The treatment has consisted of Factor VIII ampoules, administered only in the presence of hematomas.
The karyotype from lymphocyte cultures, at 450-band resolution, when the patient was 1 year old revealed a translocation between the long arms of chromosomes 1 and 19, at positions q25 and q13 (t(1;19)), and Klinefelter Syndrome, as follows: 47,XXY,t(1;19)(q25;q13), (illustrated in Fig. 2). The mother showed a normal karyotype while the father exhibited the same translocation as the proband, depicted in Fig. 2.
Moreover, an X chromosomal Short Tandem Repeat (STR) markers study was carried out on the three individuals (mother, father, and proband). DNA extraction was performed from peripheral blood samples with PureLink Genomic DNA mini kit, according to the manufacturer’s recommendations (Invitrogen™). Investigator Argus X-12 QS and X-STR Decaplex were carried out according to the manufacturer’s instructions, and as reported by a GEP-ISFG collaborative study [16], respectively. Capillary electrophoresis, in an Applied Biosystems 3500 Genetic Analyzer 8-Capillary Array (Thermo Fisher Scientific), was used for amplicon separation. The data were collected with DataCollection v. 3.3 and analyzed with GeneMapper v. 5 (Applied Biosystems) The proband’s results presented heterozygosity in different X-STRs, confirming the double dose of the X chromosome, where one X chromosome came from the mother and one X chromosome from the father. For example, in the marker DXS10103, the mother is homozygous for the allele 16, the father is homozygous for the allele 18, the proband has both alleles 16 and 18; hence, the allele 18 was inherited from the father (Additional file 1: Table S1).
At 5 years old, follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) levels were measured. The FSH levels were 1.06 mIU/mL (normal). LH levels were 1.00 mIU/mL, showing higher than normal values, supporting the diagnosis of KS. The subject underwent Spanish language development tests; the results evaluating phonological simplification processes (TEPROSIF) and the screening test of Spanish grammar (STSG) receptive and expressive showed a deficit, indicating results of someone within the 2 years old range. The diagnosis was a mixed specific language impairment, in accordance with the KS diagnosis. No treatment for the condition has started yet, given that it is recommended to start at early puberty.
To further understand the extent of the possible consequences of the chromosome 1 and 19 translocation, including insertions, deletions, and single-point mutations, Next-Generation sequencing (NGS) analyses were performed using the subject peripheral blood sample. The TruSight Inherited Disease panel (Illumina) was used; which covers 552 genes associated with severe, pediatric-onset diseases [17]. The results showed 1 341 variants that passed the quality filters; however, none of these variants were reported to be pathogenic or related to the subject’s symptomatology. No significant loss of genomic content was found, in LAMC2, and NPHS2 genes located in the q25 region of chromosome 1, neither in HAMP, COX6B1, NPHS1, DLL3, PRX, BCKDHA, ETHE1, ERCC2, OPA3, FKRP, NUP62, ETFB genes located in the q13 region of chromosome 19 (data not shown).