Introduction
Noonan syndrome is a multisystem, genetic, developmental disorder
occurring with the incidence of 1 case per 1000 to 1 case per 2500 live
births in the United -States. The condition occurs either in a sporadic
or autosomal dominant manner and affects both males and females equally.
[1] Ullrich (1930) and Turner (1938) described females with a
syndrome of short stature, sexual infantilism, and a pattern of
characteristic minor anomalies like pterygium colli. This syndrome
originally named Ullrich-Turner syndrome was later called Noonan
syndrome. It was first reported by Kobylinski (1883), but it was first
recognized as a unique entity in 1963 when Pediatrician and Heart
specialist Jacqueline Noonan and Ehmke described a series of patients
with unusual facies and multiple malformations, including congenital
heart defects. The characteristic abnormalities resemble those in Turner
syndrome, which only affects females and so Noonan syndrome was used to
be called ”Male Turner syndrome”. This term is no longer used because
Noonan syndrome can affect females also. Noonan syndrome is also called
Webbed neck syndrome, Pseudo-Ullrich Turner syndrome, Female
Pseudo-Turner syndrome, or Turner-like syndrome.[2]
The condition is mainly characterized by facial dysmorphism, congenital
heart defects, growth hormone deficiencies, webbed neck, wide space
nipples, and musculoskeletal, renal, genital, and bleeding
abnormalities. Mental retardation can also occur in about 25% of
patients with Noonan syndrome. Facial abnormalities include
hypertelorism, down-slanting eyes, webbed neck, eyelid abnormalities,
and skin manifestations. Prenatally the presentation of Noonan syndrome
is not unremarkable, however, some cases are often complicated by
polyhydramnios, fetal edema, increased nuchal translucency, and cystic
hygroma. [3,4,5]. Very little is known about the occurrence of
hypothyroidism in patients with Noon syndrome, this case report
highlights the concomitant occurrence of hypothyroidism in a patient
with Noonan syndrome, and stresses that further research should be done
to find the association of these two.
Case presentation : A 15 -year-old female patient was presented
to the outpatient department of a tertiary care hospital for bilateral
eye puffiness, easy fatiguability, and generalized body weakness. The
patient’s condition started 6 months back and it gradually worsened. On
further inquiry, the patient has a history of constipation on and off
which relieves with laxatives. The past medical history of the patient
was significant for acute hepatitis A and COVID-19 infection 3 and 1
year back respectively. The patient was born through a normal vaginal
delivery at the hospital and she was the 7th child of
his parents. The medical record of the patient showed that all the
developmental milestones were up to date, and the patient received all
the childhood vaccination. Family history was not significant for
congenital heart defects, mental retardation, short stature, or unusual
facial features. She was 135 cm tall and had 32 kg weight with vital
signs of blood pressure of 100/70 mm Hg, pulse rate of 65 beats per
minute, and respiratory rate of 15 breaths per minute. Examination
revealed pale conjunctive, down slanting eyes, hypertelorism, webbed
neck, shield chest with wide space nipple as shown in Figure.1. Systemic
examination was unremarkable except for decreased muscles power in both
upper and lower limb with a positive Gower’s sign. The patient
examination findings were suggestive of some congenital syndrome and
initially both Turner’s and Noonan were suspected. Karyotyping was done
which showed normal 46 XX chromosomes as shown in Figure.2 A diagnosis
of Noonan syndrome was made based on the clinical features and
chromosomal analysis. The patient was further evaluated for recurrent
eye puffiness and easy fatiguability and the laboratory results revealed
anemia, hypothyroidism, and increased creatinine kinase as shown in
Table. 1. A nerve conduction test and electromyography of both the upper
and lower limb were done for progressive weakness that was consistent
with mild myopathy, without evidence of spontaneous activity, mainly
affecting the proximal muscles. A final diagnosis of Noonan syndrome
with hypothyroidism that led to proximal myopathy was made. The patient
was further evaluated for cardiac, ophthalmologic, hearing, renal and
genital, and coagulation abnormalities that were all normal. The patient
and her parents were counseled about the condition, she was started on
levothyroxine 50mg OD, cap Iron sulfate 1 cap daily for two months, and
tablet opendrine and paracetamol 35/450 mg SOS for muscular pain and
weakness. She was referred to a pediatric endocrinologist for growth and
development assessment and was instructed to do close follow-up with
repeat thyroid function tests in 6 weeks and coagulation profile and
echocardiography when symptoms develop.